CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 13/121,121, filed on Sep. 16, 2009, which is the National Stage entry of PCT/EP09/06681, filed on Sep. 16, 2009, which claims priority to U.S. Provisional Application No. 61/100,255, filed on Sep. 25, 2008, all of which are incorporated herein by reference in their entireties. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to lubricant compositions having utility in numerous applications, particularly in connection with gear, transmission and/or axle applications in the automotive and machinery industries. In preferred aspects, the present invention is directed to lubricant compositions having particular advantages as axle fluids, and more particularly as heavy duty axle fluids. 
       BACKGROUND OF THE INVENTION 
       [0003]    An important function of lubricant compositions, and in particular, gear and axle lubricant fluids, is to provide a high degree of reliability and durability in the service life of equipment in which it is installed. With the increasing costs of energy, particularly gasoline and diesel fuel, the ability of such lubricants to aid in the overall fuel economy of the vehicles in which they are used has become an increasingly important factor in the selection of gear and axle lubricants. Applicants have come to appreciate that by improving the axle efficiency, particularly in heavy duty applications such as Class 8 line haul trucks and vocational vehicles, the fuel efficiency of the vehicles can be improved. 
         [0004]    Lubricating oils in general, and gear and axle lubricants in particular, must satisfy a large number of performance criteria to be commercially successful. For example, a commercially successful axle lubricant will frequently be required to possess a high degree of oxidative stability, compatibility, shear stability, corrosion avoidance or resistance, wear protection, shiftability, and extended drain. These properties represent a difficult-to-achieve set of performance criteria that is made all the more difficult to achieve if the requirement of enhancing fuel efficiency is also added. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    Applicants have developed improved lubricant compositions, and in many embodiments lubricant compositions, that satisfy at a high level of performance, many, and preferably all, of the criteria mentioned above. As used herein, the term “lubricant composition” is used in its broadest sense to include fluid compositions that are used in applications involving metal-to-metal contact of parts in which at least one function of the fluid is to inhibit or reduce friction between the parts. As such, the term “lubricant composition”, as used herein, includes gear oils, axle oils and the like. 
         [0006]    Preferably the lubricant compositions of the present invention comprise (a) basestock; (b) viscosity improver; and (c) at least one additive to inhibit, and preferably substantially prevent, one or more of wearing, scuffing, micropitting and combinations of these and other deleterious effects. In preferred embodiments the lubricant compositions of the present invention comprise (a) basestock comprising poly-alpha-olefin (hereinafter referred to as “PAO”), preferably low viscosity PAO, and even more preferably a PAO having a viscosity of not greater than about 12 centistokes (cSt), and optionally an ester oil; (b) viscosity improver comprising at least one high viscosity PAO-type viscosity improver, preferably having a viscosity of greater than about 40 centistokes (cSt), and even more preferably from about 40 to about 1000 cSt; and (c) a performance additive package comprising at least one additive effective to improve at least one property of the lubricant and/or the performance of the equipment in which the lubricant is to be used. In certain preferred embodiments, the performance additive comprises at least one sulfur-containing compound and at least one phosphorous-containing compound. 
         [0007]    Applicants have found that preferred lubricant compositions of the present invention exhibit and/or produce one or more, and preferably all, of the following advantageous properties: reduction of viscous drag over the application temperature range; film thickness reduction; and churning loss reduction. 
         [0008]    In preferred embodiments, the present lubricant compositions exhibit a horsepower (HP) loss reduction, as described and measured in connection with the examples hereof, of at least about 3%, more preferably at least about 4%, and even more preferably at least about 5%. 
         [0009]    In preferred embodiments, the present lubricant compositions exhibit a sump temperature reduction, as described and measured in connection with the examples hereof, of at least about 2%, more preferably at least about 5%, and even more preferably at least about 7%. 
         [0010]    Other embodiments of the present invention are directed to methods of making and using a fully formulated lubricant, including a fully formulated heavy duty axle fluid. A final embodiment of the invention is directed to axle, gear, transmission and/or drive systems containing such oils. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  displays pictures of gear components illustrating the sludge control properties of a lubricant composition of the invention versus standard lubricants. 
           [0012]      FIG. 2  shows a graph of frictional properties of lubricant compositions of the invention versus standard lubricants. 
           [0013]      FIG. 3  shows a schematic diagram of a test apparatus for evaluating frictional properties of a lubricant composition. 
           [0014]      FIG. 4  shows a graph of traction properties of lubricant compositions of the invention versus standard lubricants. 
           [0015]      FIG. 5  shows a schematic diagram of a test apparatus for evaluating the traction properties of a lubricant composition. 
           [0016]      FIG. 6  shows a graph of the seal compatibility properties of lubricant compositions of the invention versus standard lubricants. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0017]    The present invention is directed in one aspect to lubricant compositions comprising at least one base stock, at least one viscosity enhancer for the base stock, and at least one additive. In general, it is contemplated that these components of the present invention may be present in the compositions in widely varying amounts depending on the particular needs of each application, and all such variations are considered to be within the broad scope of the invention. Nevertheless, applicants have found that in certain preferred embodiments, the present lubricant compositions are formulated according to the following preferred ranges of components, it being understood that all percentage values indicated in Table 1 are modified by the word “about”. 
         [0000]    
       
         
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Broad 
                 Intermediate 
                 Narrow 
               
               
                   
                 Wt % Range 
                 Wt % Range 
                 Wt % Range 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Basestock 
                 10-90  
                 15-80  
                 15-60  
               
               
                   
                 Viscosity 
                 2-70 
                 5-60 
                 5-60 
               
               
                   
                 Improver 
               
               
                   
                 Additive 
                 2-30 
                 5-20 
                 5-15 
               
               
                   
                   
               
             
          
         
       
     
         [0018]    With respect to certain preferred embodiments, the base stock comprises at least one low viscosity PAO and at least one adipate ester. While it is contemplated that a wide range of relative concentrations of such components may be present, in general it is preferred that the base stock of the present invention comprise in certain embodiments a PAO:ester weight ratio of from about 0.5 to about 12:1, and more preferably of from about 0.5 to about 12:1. In certain embodiments it is also preferred that the viscosity improver comprise a high viscosity PAO (hereinafter HVPAO) and an additional additive selected from the group consisting of PIB (polyisobutylene), PMA (polymethacrylate), or OCP (olefin co-polymer), and combinations of two or more of these. While it is contemplated that a wide range of relative concentrations of such components may be present, in general it is preferred that the viscosity enhancer of the present invention comprise in certain embodiments an additional additive:HVPAO weight ratio of from about 0 to about 4:1, and more preferably of from about 0.2 to about 4:1. 
         [0019]    Applicants have found that in certain preferred embodiments the present lubricant compositions are formulated according to the following preferred ranges of components, it being understood that all percentage values indicated in Table 2 are modified by the word “about”. 
         [0020]    Although it is contemplated that the PAO used in connection with the base stock component of the present invention may vary widely in particular properties and/or structures, in certain embodiments the PAO component is a PAO having a viscosity of from about 4 to about 12 cSt. In preferred embodiments the PAO is selected from group consisting of PAOs having a viscosity of about 4, 6, 8, 10, 12 or combinations of two or more of these. In certain preferred embodiments, the PAO used in connection with the base stock component of the present invention is comprised of oligomeric compounds having from 2 to about 3 units, preferably units of 1-decene. 
         [0021]    Although it is also contemplated that the PAO used in connection with the viscosity enhancer component of the present invention may vary widely in particular properties and/or structures, in certain embodiments the PAO component of the viscosity enhancer comprises, and preferably in certain embodiments consists essentially of a PAO having a viscosity greater than about 40 cSt, and even more preferably from about 40 to about 1000 cSt. In preferred embodiments, the PAO component of the viscosity enhancer is comprised of polymeric compounds having greater than about 50 units, more preferably having greater than about 75 units and even more preferably having greater than about 100 units, preferably units of 1-decene. 
         [0000]    
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 Broad 
                 Intermediate 
                 Narrow 
               
               
                   
                 Wt % Range 
                 Wt % Range 
                 Wt % Range 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Basestock - 
                  2-30 
                  5-30 
                  5-20 
               
               
                 adipate ester 
               
               
                 Basestock - 
                 10-70 
                 10-60 
                 10-40 
               
               
                 PAO 
               
               
                 (preferably 4-12 cSt 
               
               
                 or 6-8 cSt) 
               
               
                 Viscosity 
                  2-50 
                  5-50 
                  5-40 
               
               
                 Improver - 
               
               
                 HVPAO 
               
               
                 Additive - 
                  0-30 
                  0-25 
                  0-20 
               
               
                 ANGAMGL ® 
               
               
                 6004j or GL-4 
               
               
                 Gear Oil package 
               
               
                 Additive - PMA 
                 0-3 
                 0-2 
                 0-1 
               
               
                 Additive - 
                 0-3 
                 0-2 
                 0-1 
               
               
                 Defoamer 
               
               
                 (silicone based) 
               
               
                   
               
             
          
         
       
     
         [0022]    Applicants believe that, in general, numerous particular compounds or combinations of compounds are available for use in connection with each of the ingredients as described herein. With respect to the optional adipate ester, it is preferred in certain embodiments that the adipate ester comprises a decyl adipate, and even more particularly, of one or more adipate esters selected from the group consisting of di-isodecyl adipate, and di-tridecyl adipate. In a further embodiment, the preferred ester comprises di-isodecyl azelate. 
         [0023]    In certain preferred embodiments, the present lubricant compositions are formulated in accordance with Tables 3 or 4 below, it being understood that the amounts are weight percentages and the each value is understood to be preceded by the word “about”. 
         [0000]    
       
         
               
               
               
               
             
           
               
                   
                 TABLE 3 
               
               
                   
                   
               
             
             
               
                   
                 Basestock 
                 adipate 
                 5-20% 
               
               
                   
                 Basestock 
                 Low Viscosity PAO (4-12 cSt) 
                 20-60% 
               
               
                   
                 Thickener 
                 PAO 40-1000 
                 5-40% 
               
               
                   
                 Thickener 
                 PIP, PMA or OCP 
                 0-20% 
               
               
                   
                 Adpack 
                 GL-4 Gear Oil Package 
                 5-15% 
               
               
                   
                 PPD 
                 PMA Polymer 
                 0-2.0% 
               
               
                   
                 Defoamer 
                 Silicone based 
                 0-2.0% 
               
               
                   
                   
               
             
          
         
       
     
         [0000]    
       
         
               
               
               
               
             
           
               
                   
                 TABLE 4 
               
               
                   
                   
               
             
             
               
                   
                 Basestock 
                 di-isodecyl adipate 
                 5-20% 
               
               
                   
                 Basestock 
                 Low Viscosity PAO (6-8 cSt) 
                 10-40% 
               
               
                   
                 Thickener 
                 PAO 40-100 
                 5-40% 
               
               
                   
                 Thickener 
                 PIP or OCP 
                 0-20% 
               
               
                   
                 Adpack 
                 ANGAMOL ® 6004J 
                 5-15% 
               
               
                   
                 PPD 
                 PMA Polymer 
                 0-1.0% 
               
               
                   
                 Defoamer 
                 Silicone based 
                 0-1.0% 
               
               
                   
                   
               
             
          
         
       
     
       EXAMPLES 
       [0024]    The following examples are provided for the purpose of illustrating the present invention but without limiting the scope thereof. 
       Average Horsepower Loss 
     Comparative Examples C1-C4 and Examples E1-E4 
       [0025]    The average horsepower loss (“AHPL”) is one measure that can be used to represent the performance of a lubricant composition, particularly an axle or gear oil, with respect to the fuel economy impact on the vehicle in which it will be used. In order to obtain information regarding the relative performance of certain preferred lubricants in accordance with the present invention, a testing protocol is used in which a commercial axle is attached to a dynamometer which es the input and the output torque on the axle. This test is run for comparison purposes with several commercially available lubricants and also with two formulations in accordance with the preferred embodiments of the present invention. In order to help assess the relative performance of the different lubricant formulations, a commercially available product sold under the trade designation EMGARD® 2986 is tested several times (identified with row headings C1A-C1F) in order to establish an average value for comparison purposes, which values are reported at the end of Table 5. The results of the test done in connection with the commercially available products are identified across the row headings C1-C4 in Table 5. The results of the tests performed in connection with four lubricant compositions of the present invention are reported-as E1-E4. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE 5 
               
               
                   
                   
               
               
                   
                   
                 Ending 
                   
                 Sump 
               
               
                   
                   
                 Sump 
                 Hp Loss 
                 Temp 
               
               
                   
                 Average 
                 Temp 
                 Reduc- 
                 Reduc- 
               
               
                   
                 Hp Loss 
                 (C.) 
                 tion % 
                 tion % 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 C1A -EMGARD ® 
                 2.924 
                 82.5 
                 −0.5% 
                 −1.4% 
               
               
                 2986 
               
               
                 E1 -Cognis 3 
                 2.847 
                 80.6 
                 2.1% 
                 0.9% 
               
               
                 (704-156-4 
               
               
                 E2 - 100 cSt PAO 
                 2.750 
                 77.0 
                 5.45 
                 5.3% 
               
               
                 (770-11-11) 
               
               
                 C1B -EMGARD ® 
                 2.891 
                 84.6 
                 0.6% 
                 −4.0% 
               
               
                 2986 
               
               
                 C1C -EMGARD ® 
                 2.894 
                 80.5 
                 0.5% 
                 1.1% 
               
               
                 2986 
               
               
                 C2 -EMGARD ® 4209 
                 2.893 
                 80.3 
                 0.5% 
                 1.3% 
               
               
                 Aged (770-26-2) 
               
               
                 C3 - Q8 (188-185) 
                 2.841 
                 77.2 
                 2.3% 
                 5.1% 
               
               
                 C1D -EMGARD ® 
                 2.930 
                 80.1 
                 −0.7% 
                 1.5% 
               
               
                 2986 
               
               
                 E3 -PAO100/PIB/PA08 
                 2.800 
                 76.6 
                 3.7% 
                 5.9% 
               
               
                 (770-39-1) 
               
               
                 E4 -PAO100/PA06 
                 2.783 
                 75.2 
                 4.3% 
                 7.5% 
               
               
                 (770-42-1) 
               
               
                 C4 -LUCANT ® 
                 2.917 
                 80.2 
                 −0.3% 
                 1.4% 
               
               
                 600/PA08 (770-35-7) 
               
               
                 C1F -EMGARD ® 
                 2.907 
                 80.1 
                 0.1% 
                 1.5% 
               
               
                 2986 
               
               
                 EMGARD ® 
                 2.908 
                 81.3 
               
               
                 2986 (ave) 
               
               
                 EMGARD ® 
                 2.908 
                 81.3 
               
               
                 2986 (ave) 
               
               
                 EMGARD ® 
                 0.016 
                 1.836 
               
               
                 2986 (stdev) 
               
               
                 EMGARD ® 
                 0.54% 
                 2.26% 
               
               
                 2986 (% dev) 
               
               
                   
               
             
          
         
       
     
         [0026]    As can be seen from Table 5, the lubricant composition in accordance with the present invention labeled E2 exhibited a 5.4% relative improvement in energy efficiency compared to the average established for EMGARD® 2896. The formulation designated as E2 in Table 5 consisted essentially of (CAS #770-11-11) di-isodecyl adipate (5%). PAO 8 (56.6%). PAO 100 (28%). ANGAMOL® 6004J (10%), HiTEC 5739 (0.3%), E-9817U (0.1%), with all amounts being reported on the basis of weight percent. Also as can be seen from Table 5 above, the lubricant composition in accordance with the present invention labeled E3 exhibited a 3.7% relative improvement in energy efficiency compared to the average established for EMGARD® 2896. The formulation designated as E3 in Table 5 consisted essentially of (CAS #770-39-1) di-isodecyl adipate (5%), PAO 8 (56.6%), PAO 100 (13%), INDOPOL® H-1500 SPA (13%), ANGAMOL® 6004J (10%), HiTEC 5739 (0.3%), E-9817U (0.1%), with all amounts being reported on the basis of weight percent. And finally, the lubricant composition in accordance with the present invention labeled E4 exhibited a 4.3% relative improvement in energy efficiency compared to the average established for EMGARD® 2896. The formulation designated as E4 in Table 5 consisted essentially of (CAS #770-42-1) di-isodecyl adipate (5%), PAO 8 (51.6%), PAO 100 (33%), ANGAMOL® 6004J (10%), HiTEC 5739 (0.3%), and E-9817U (0.1%), with all amounts being reported on the basis of weight percent. 
       Physical Properties 
     Comparative Examples C1, C5, C6 and C7 and Examples Cognis #2 and Cognis #3 
       [0027]    Several properties exist which, at least in certain applications, are considered relevant to the effectiveness of lubricant compositions. Tests are performed for the purpose of obtaining information regarding the relative performance of certain preferred lubricants in accordance with the present invention relative to several commercially available lubricants. The results of the test done for comparison purposes in connection with the commercially available products are identified under column headings EMGARD® 4209, EMGARD® 2986, Comp Q and Comp S in Table 6. The results of the tests performed in connection with two lubricant compositions of the present invention are based on the same formulation reported in Table 5 as E1 and E2, but labeled in Table 6 with row headings Cognis #2 and Cognis #3, respectively. 
         [0028]    Based upon the results reported in Table 6, it is seen that the lubricant compositions in accordance with the present invention exhibit excellent shear stability and low temperature properties relative to leading commercially available axle lubricants. 
       Corrosion and Anti-Wear Properties 
     Comparative Examples C1, C5, C6 and C7 and Examples Cognis #2 and Cognis #3 
       [0029]    Several properties exist which, at least in certain applications, are considered relevant to the anti-corrosion and anti-wear abilities of lubricant compositions. Several tests are performed for the purpose of obtaining information regarding the relative performance of certain preferred lubricants in accordance with the present invention relative to several commercially available lubricants. The results of the test done for comparison purposes in connection with the commercially available products are identified under column headings EMGARD® 4209, EMGARD® 2986, Comp Q and Comp S in Table 7. The results of the tests performed in connection with two lubricant compositions of the present invention are based on the same formulation reported in Table 5 as E1 and E2, but labeled in Table 7 with row headings Cognis #2 and Cognis #3, respectively. 
         [0030]    Based upon the results reported in Table 7, it is seen that the lubricant compositions in accordance with the present invention exhibit excellent corrosion resistance and wear resistance properties. 
       Stability 
     Comparative Examples C1, C5, C6 and C7 and Examples Cognis #2 and Cognis #3 
       [0031]    Several properties exist which, at least in certain applications, are considered relevant to the stability of lubricant compositions in the environment of use. Several tests are performed for the purpose of obtaining information regarding the relative performance of certain preferred lubricants in accordance with the present invention relative to several commercially available lubricants. The results of the test done for comparison purposes in connection with the commercially available products are identified under column headings EMGARD® 4209, EMGARD® 2986, Comp Q and Comp S in the Table 8. The results of the tests performed in connection with two lubricant compositions of the present invention are based on the same formulation reported in Table 5 as E1 and E2, but labeled in Table 8 with row headings Cognis #2 and Cognis #3, respectively. 
         [0032]    Based upon the results reported in Table 8, it is seen that the lubricant compositions in accordance with the present invention exhibit excellent stability. 
       Sludge Control 
     Comparative Examples C1, C5, C6 and C7 and Examples Cognis #2 and Cognis #3 
       [0033]    Several properties exist which, at least in certain applications, are considered relevant to the ability of lubricant compositions to have a positive effect on the control of sludge creation and/or build up in the environment of use. Several tests are performed for the purpose of obtaining information regarding the relative performance of certain preferred lubricants in accordance with the present invention relative to several commercially available lubricants. The results of the test done for comparison purposes in connection with the commercially available products are identified under column headings EMGARD® 4209, EMGARD® 2986, Comp Q and Comp S in the Table 9, and associated  FIG. 1 . The results of the tests performed in connection with two lubricant compositions of the present are based on the same formulation reported in Table 5 as E1 and E2, but labeled in Table 9 with row headings Cognis #2 and Cognis #3, respectively. 
         [0034]    Based upon the results reported in Table 9 and  FIG. 1 , it is seen that the lubricant compositions in accordance with the present invention exhibit excellent sludge control. 
       Wear Control 
     Comparative Examples C1, C5, C6 and C7 and Examples Cognis #2 and Cognis #3 
       [0035]    Several properties exist which, at least in certain applications, are considered relevant to the ability of lubricant compositions to resist or reduce the rate of wear of the moving metal parts with which it is in contact in the environment of use. Several tests are performed for the purpose of obtaining information regarding the relative performance of certain preferred lubricants in accordance with the present invention relative to several commercially available lubricants. The results of the test done for comparison purposes in connection with the commercially available products are identified under column headings EMGARD® 4209, EMGARD® 2986, Comp Q and Comp S in the Table 10. The results of the tests performed in connection with two lubricant compositions of the present invention are based on the same formulation reported in Table 5 as E1 and E2, but labeled in Table 10 with row headings Cognis #2 and Cognis #3, respectively. 
         [0036]    Based upon the results reported in Table 10, it is seen that the lubricant compositions in accordance with the present invention exhibit excellent wear resistant properties. 
       Frictional Properties 
     Comparative Examples C1, C5, C6 and C7 and Examples Cognis #2 and Cognis #3 
       [0037]    The frictional properties of a lubricant composition are in general considered to be highly relevant to the ability of lubricant compositions to exhibit superior performance in the environment of use. Several tests are performed for the purpose of obtaining information regarding the relative performance of certain preferred lubricants in accordance with the present invention relative to several commercially available lubricants. The results of the test done for comparison purposes in connection with the commercially available products are identified under column headings EMGARD® 4209, EMGARD® 2986, Comp Q and Comp S in  FIG. 2 . The results of this test in accordance with the present invention are based on the same formulation reported in Table 5 as E1 and E2, but labeled in  FIG. 2  as Cognis #2 and Cognis #3, respectively 
         [0038]    One method of testing the frictional properties of lubricant is to utilize a 19.05 mm (¾ inch) steel ball and 46 mm diameter steel desk. The ball is loaded against the face of the disc and the ball and the disc are driven independently to create a mixed rolling/sliding contact. The force between the ball and disk is measured by a force transducer. Additional sensors measure the applied load, the lubricant temperature and (optionally) electrical contact resistance between specimens and the relative wear between them. A schematic diagram of such a test apparatus is provided in  FIG. 3 . 
         [0039]    Such an apparatus is used to test lubricant compositions in accordance with the present invention, using a film thickness of one to 1000 nm (±1 nm), speeds of 0.010-1.0 m/s, loads of 100 N, a slide/roll ratio (SSR) of 50%, contact pressures of up to approximately 3.0 GPa, a temperature range of from 40 to 100° C., a power supply of from 100 to about 240 V, a total weight of 50 kg and dimensions (W×H×D) of 50×50×30 cm. The results of this test indicate that lubricant compositions in accordance with preferred aspects of the present invention produce exceptionally low friction coefficients relative to other commercially available lubricant compositions, as identified in  FIG. 2 . 
       Traction Properties 
     Comparative Examples C1, C5, C6 and C7 and Examples Cognis #2 and Cognis #3 
       [0040]    The traction properties of a fluid in many instances are relevant to the ability of lubricant compositions to exhibit superior performance in the environment of use. Several tests are performed for the purpose of obtaining information regarding the relative performance of certain preferred lubricants in accordance with the present invention relative to several commercially available lubricants. The results of the test done for comparison purposes in connection with the commercially available products are identified under column headings EMGARD® 4209, EMGARD® 2986, Comp Q and Comp S in  FIG. 4 . The results of the tests performed in connection with two lubricant compositions of the present invention are based on the same formulation reported in Table 5 as E1 and E2, but labeled in  FIG. 4  as Cognis #2 and Cognis #3, respectively. 
         [0041]    One method of testing the traction properties of a lubricant composition is to measure the thickness and traction properties of elastohydrodynamic lubricant (EHL) films utilizing an apparatus having at least one bowl or roller loaded against the internal diameter of a transparent ring having a larger radius than the bowl or roller. The lubricant to be tested is placed between the rotating roller and arraying thereby forming an EHL film where the ball and arraying contact. Roller and arraying rotating speeds are controlled to obtain different amounts of relative sliding motion between the respective surfaces. Contact between the surfaces and the resultant film are observed by way of a transparent ring which allows optical measurements of lubricating film thickness. Traction forces generated during contact are also measured. A schematic diagram of such a test apparatus is provided in  FIG. 5 . 
         [0042]    Such an apparatus is used to test lubricant compositions in accordance with the present invention, using a film thickness of one to 1000 nm (±1 nm), speeds of 0.010-3.5 m/s, loads of 1 to 50 N, a slide/roll ratio (SSR) of 50%, contact pressures of up to approximately 3.0 GPa, a temperature range of from 40 to 100° C., a power supply of from 100 to about 240 V, a total weight of 50 kg and dimensions (W×H×D) of 50×50×30 cm. The results of this test indicate that lubricant compositions in accordance with preferred aspects of the present invention produced acceptable film thicknesses, especially at temperatures of 40° C., relative to other commercially available lubricant compositions, as identified in  FIG. 4 . 
       Seal Compatibility 
     Comparative Examples C1, C5, C6 and C7 and Examples Cognis #2 and Cognis #3 
       [0043]    One property of lubricant compositions which is considered to be important, at least in certain applications, is the compatibility of the lubricant with nonmetal parts in the system and environment of use, especially including seals, gaskets and the like. Several tests are performed for the purpose of obtaining information regarding the relative performance of certain preferred lubricants in accordance with the present invention relative to several commercially available lubricants in connection with seal compatibility. The results of the test done for comparison purposes in connection with the commercially available products are identified under column headings EMGARD® 4209, EMGARD® 2986, Comp Q and Comp S in Table 11 and  FIG. 6 . The results of the tests performed in connection with two lubricant compositions of the present invention are based on the same formulation reported in Table 5 as E1 and E2, but labeled in Table 11 with row headings Cognis #2 and Cognis #3, respectively. 
         [0044]    Based upon the results reported in Table 11 and the associated graph,  FIG. 6 , it is seen that the lubricant compositions in accordance with the present invention exhibit, or would be expected to exhibit, excellent compatibility with the seals, gaskets and the like, used in connection with the systems and devices in which the present lubricant compositions are intended to be included. 
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 6 
               
             
             
               
                   
               
               
                 PHYSICAL PROPERTIES OF LUBRICANT COMPOSITIONS, 
               
             
          
           
               
                 Physical 
                   
                 EMGARD ® 
                 EMGARD ® 
                 Cognis 
                 Cognis 
                 Comp 
                 Comp 
               
               
                 Properties 
                   
                 4209 
                 2986 
                 #2 
                 #3 
                 Q 
                 S 
               
               
                   
               
             
          
           
               
                 Kinematic 
                 ASTM 
                 16.8 
                 15.0 
                 14.5 
                 14.83 
                 14.59 
                 14.59 
               
               
                 Viscosity 
                 D445 
                   
                   
                   
                   
                   
                   
               
               
                 @ 100° C., cST 
                   
                   
                   
                   
                   
                   
                   
               
               
                 Kinematic 
                 ASTM 
                 115 
                 103.0 
                 95.45 
                 100.25 
                 94.73 
                 93.55 
               
               
                 Viscosity @ 
                 D445 
                   
                   
                   
                   
                   
                   
               
               
                 40° C., cST 
                   
                   
                   
                   
                   
                   
                   
               
               
                 Kinematic 
                 ASTM 
                 115,000 
                 92,000 
                 83,000 
                 130,500 
                 161,200 
                 168,000 
               
               
                 Viscosity @ 
                 D445 
                   
                   
                   
                   
                   
                   
               
               
                 −40° C., cSt 
                   
                   
                   
                   
                   
                   
                   
               
               
                 Brookfield 
                 ASTM 
                 186,000 
                 90,000 
                 68,000 
                 62,000 
                 121,300 
                 82,200 
               
               
                 Viscosity @ 
                 D2983 
                   
                   
                   
                   
                   
                   
               
               
                 −40° C., cP 
                   
                   
                   
                   
                   
                   
                   
               
               
                 Viscosity Index 
                 ASTM 
                 160 
                 152 
                 158 
                 154 
                 160 
                 154 
               
               
                 (calculated) 
                 D2270 
                   
                   
                   
                   
                   
                   
               
               
                 Viscosity Shear 
                 CEC L- 
                 9.98 
                 10.38 
                 11.59 
                 1.50 
                 6.12 
                 9.59 
               
               
                 Loss, 60 h 
                 45-A-99 
                   
                   
                   
                   
                   
                   
               
               
                 Channel Point, 
                 FTMS- 
                 −45 
                 −45 
                 −45 
                 −45 
                 −45 
                 −45 
               
               
                 ° C. 
                 3456.2 
                   
                   
                   
                   
                   
                   
               
               
                 Pour Point, ° C. 
                 ASTM 
                 −50 
                 −57 
                 −45 
                 −45 
                 −45 
                 −51 
               
               
                   
                 D97 
                   
                   
                   
                   
                   
                   
               
               
                 Flash Point, ° C. 
                 ASTM 
                 220 
                 215 
                 210 
                 210 
                 218 
                 207 
               
               
                   
                 D92 
                   
                   
                   
                   
                   
                   
               
               
                 Specific Gravity,  
                 ASTM 
                 0.863 
                 0.891 
                 0.8573 
                 0.8531 
                 0.8607 
                 0.8733 
               
               
                 15.6° C. 
                 D4052 
                   
                   
                   
                   
                   
                   
               
               
                 Density, g/L 
                 ASTM 
                 863 
                 891 
                 856 
                 853 
                 868 
                 872 
               
               
                 @ 15.6° C. 
                 D1298 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 7 
               
             
             
               
                   
               
               
                 CORROSION AND ANTI-WEAR PROPERTIES OF LUBRICANT 
               
               
                 COMPOSITIONS. 
               
             
          
           
               
                   
                   
                 EMGARD ® 
                 EMGARD ® 
                 Cognis 
                 Cognis 
                 Comp 
                 Comp 
               
               
                   
                   
                 4209 
                 2986 
                 #2 
                 #3 
                 Q 
                 S 
               
               
                   
               
             
          
           
               
                 Foam Test 
                 ASTM D892 
                   
                   
                   
                   
                   
                   
               
               
                 Sequence I 
                   
                 0/0 
                 0/0 
                 0/0 
                 0/0 
                 20/0 
                  0/0 
               
               
                 Sequence II 
                   
                 10/0  
                 50/0  
                 0/0 
                 0/0 
                 270/0  
                 100/0 
               
               
                 Sequence III 
                   
                 0/0 
                 0/0 
                 0/0 
                 0/0 
                 20/0 
                  0/0 
               
               
                 Copper Strip 
                 ASTM D130 
                   
                   
                   
                   
                   
                   
               
               
                 Corrosion 
                   
                   
                   
                   
                   
                   
                   
               
               
                 3 hrs @ 121° C. 
                   
                 1b 
                 1a 
                 1a 
                 1b 
                 2e 
                 3a 
               
               
                 Four Ball EP 
                 ASTM D2783 
                   
                   
                   
                   
                   
                   
               
               
                 Load-Wear 
                   
                 77.0 
                 83.7 
                 72.0 
                 78.0 
                 69.8 
                 62.2 
               
               
                 Index, kgf 
                   
                 400 
                 500 
                 400 
                 400 
                 315 
                 400 
               
               
                 Weld Point, kg 
                   
                   
                   
                   
                   
                   
                   
               
               
                 Four Ball 
                 ASTM D4172 
                   
                   
                   
                   
                   
                   
               
               
                 Wear 
                   
                   
                   
                   
                   
                   
                   
               
               
                 Scar Diameter, 
                   
                 0.44 
                 0.74 
                 0.42 
                 0.43 
                 0.53 
                 0.57 
               
               
                 mm 
                   
                   
                   
                   
                   
                   
                   
               
               
                 FZG, Step 
                 acc. FVA-243 
                 &gt;10 
                   
                 &gt;10 
                   
                 &gt;10 
                 &gt;10 
               
               
                 Load (Sprung) 
                 S- 
                   
                   
                   
                   
                 (est)  
                 (est) 
               
               
                 Test, stage 
                 A10/16.6R/90 
                   
                   
                   
                   
                   
                   
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 8 
               
             
             
               
                   
               
               
                 STABILITY PROPERTIES OF LUBRICANT COMPOSITIONS. 
               
             
          
           
               
                   
                   
                 EMGARD ® 
                 EMGARD ® 
                 Cognis 
                 Cognis 
                 Comp 
                 Comp 
               
               
                   
                   
                 4209 
                 2986 
                 #2 
                 #3 
                 Q 
                 S 
               
               
                   
               
             
          
           
               
                 Oxidation DKA 
                 CEC L- 
                   
                   
                   
                   
                   
                   
               
               
                 (192 hrs., 160° C.) 
                 48-A-00 
                   
                   
                   
                   
                   
                   
               
               
                 Fresh 
                   
                   
                   
                   
                   
                   
                   
               
               
                 Kinematic 
                 ASTM 
                 16.87 
                 14.97 
                 14.65 
                 14.92 
                 14.44 
                 14.52 
               
               
                 Viscosity @ 
                 D445 
                   
                   
                   
                   
                   
                   
               
               
                 100° C., cST 
                   
                   
                   
                   
                   
                   
                   
               
               
                 Kinematic 
                 ASTM 
                 117.3 
                 103.46 
                 96.99 
                 97.73 
                 93.3 
                 105.33 
               
               
                 Viscosity @ 40° C.,  
                 D445 
                   
                   
                   
                   
                   
                   
               
               
                 cSt 
                   
                   
                   
                   
                   
                   
                   
               
               
                 TAN 
                 CEC L- 
                 2.4 
                 1.92 
                 2.5 
                 1.72 
                 1.39 
                 2.17 
               
               
                   
                 48-A-00 
                   
                   
                   
                   
                   
                   
               
               
                 Aged 
                   
                   
                   
                   
                   
                   
                   
               
               
                 Kinematic 
                 ASTM 
                 31.84 
                 26.28 
                 22.09 
                 18.95 
                 20.46 
                 24.81 
               
               
                 Viscosity @ 
                 D445 
                   
                   
                   
                   
                   
                   
               
               
                 100° C., cST 
                   
                   
                   
                   
                   
                   
                   
               
               
                 Kinematic 
                 ASTM 
                 261.9 
                 202.73 
                 161.9 
                 132.75 
                 139.54 
                 207.42 
               
               
                 Viscosity @ 40° C., 
                 D445 
                   
                   
                   
                   
                   
                   
               
               
                 cSt 
                   
                   
                   
                   
                   
                   
                   
               
               
                 TAN, mgKOH/g 
                 ASTM 
                 5.8 
                 4.03 
                 5.1 
                 2.11 
                 2.62 
                 6.68 
               
               
                   
                 D664 
                   
                   
                   
                   
                   
                   
               
               
                 PAI (peak area 
                 CEC L- 
                 143.9 
                 18.70 
                 100.3 
                 17.59 
                 26.94 
                 41.57 
               
               
                 increase) 
                 48-A-00 
                   
                   
                   
                   
                   
                   
               
               
                 Sludge Rating, 
                 CEC L- 
                 3 
                 1 
                 2 
                 3 
                 3 
                 1 
               
               
                 Aspect 
                 48-A-00 
                   
                   
                   
                   
                   
                   
               
               
                 Dispersancy 
                   
                   
                   
                 86 
                   
                   
                   
               
               
                 (blotter test) 
                   
                   
                   
                   
                   
                   
                   
               
               
                 Variation 
                   
                   
                   
                   
                   
                   
                   
               
               
                 Variation 
                   
                 88.7 
                 75.6 
                 50.8 
                 27.0 
                 41.7 
                 70.9 
               
               
                 Kinematic Vis. @ 
                   
                   
                   
                   
                   
                   
                   
               
               
                 100° C., % 
                   
                   
                   
                   
                   
                   
                   
               
               
                 Variation 
                   
                 123.3 
                 96.0 
                 66.9 
                 35.8 
                 49.6 
                 96.9 
               
               
                 Kinematic Vis. @ 
                   
                   
                   
                   
                   
                   
                   
               
               
                 40° C., % 
                   
                   
                   
                   
                   
                   
                   
               
               
                 Variation TAN, 
                   
                 3.4 
                 2.1 
                 2.6 
                 0.39 
                 1.2 
                 4.5 
               
               
                 mgKOH/g 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 9 
               
             
             
               
                   
               
               
                 SLUDGE CONTROL PROPERTIES OF LUBRICANT COMPOSITIONS. 
               
             
          
           
               
                   
                   
                 EMGARD ® 
                 EMGARD ® 
                 Cognis 
                 Cognis 
                 Comp 
                 Comp 
               
               
                   
                   
                 4209 
                 2986 
                 #2 
                 #3 
                 Q 
                 S 
               
               
                   
               
               
                 Oxidation L-60-1 
                 ASTM 
                   
                   
                   
                   
                   
                   
               
               
                 (200 hrs, 163° C.) 
                 D5704 
                   
                   
                   
                   
                   
                   
               
               
                 Viscosity 
                   
                 37.5 (50 h) 
                 93 
                 75.1 
                   
                 23.8 
                 67.3 
               
               
                 Increase, % 
                   
                   
                   
                   
                   
                   
                   
               
               
                 C/V Rating, merit 
                   
                 9.55 (50 h)  
                 9.1 
                 9.0 
                   
                 1.5 
                 8.5 
               
               
                 Sludge Rating, 
                   
                  9.5 (50 h) 
                 9.6 
                 9.0  
                   
                 1.5 
                 8.5 
               
               
                 merit 
                   
                   
                   
                   
                   
                   
                   
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 10 
               
             
             
               
                   
               
               
                 WEAR CONTROL PROPERTIES OF LUBRICANT COMPOSITIONS. 
               
             
          
           
               
                   
                   
                 EMGARD ® 
                 EMGARD ® 
                 Cognis 
                 Cognis 
                 Comp 
                 Comp 
               
               
                   
                   
                 4209 
                 2986 
                 #2 
                 #3 
                 Q 
                 S 
               
               
                   
               
             
          
           
               
                 High Temperature 
                 ASTM 
                   
                   
                   
                   
                   
                   
               
               
                 Towing HT-L-37 
                 D6121 
                   
                   
                   
                   
                   
                   
               
               
                 Ring Gear 
                   
                   
                   
                   
                   
                   
                   
               
               
                 Wear 
                   
                   
                 8.0 
                 7.0 
                   
                 7.0 
                 5.0 
               
               
                 Rippling 
                   
                   
                 9.0 
                 10.0 
                   
                 10.0 
                 8.0 
               
               
                 Ridging 
                   
                   
                 10 
                 10.0 
                   
                 10.0 
                 5.0 
               
               
                 Pitting/Spalling 
                   
                   
                 9.9 
                 9.9 
                   
                 10.0 
                 8.0 
               
               
                 Scoring 
                   
                   
                 10 
                 10.0 
                   
                 10.0 
                 10.0 
               
               
                 Pinion Gear 
                   
                   
                   
                   
                   
                   
                   
               
               
                 Wear 
                   
                   
                 8.0 
                 7.0 
                   
                 7.0 
                 4.0 
               
               
                 Rippling 
                   
                   
                 9.0 
                 9.0 
                   
                 10.0 
                 7.0 
               
               
                 Ridging 
                   
                   
                 10 
                 9.0 
                   
                 9.0 
                 4.0 
               
               
                 Pitting/Spalling 
                   
                   
                 9.9 
                 9.9 
                   
                 10.0 
                 8.0 
               
               
                 Scoring 
                   
                   
                 10 
                 10.0 
                   
                 10.0 
                 10.0 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 11 
               
             
             
               
                   
               
               
                 SEAL COMPATIBILITY PROPERTIES OF LUBRICANT COMPOSITIONS. 
               
             
          
           
               
                   
                 EMGARD ® 
                 EMGARD ® 
                 Cognis 
                 Cognis 
                 Comp 
                 Comp 
               
               
                   
                 4209 
                 2986 
                 #2 
                 #3 
                 Q 
                 S 
               
               
                   
               
             
          
           
               
                 Thickness @ 40° C. (1.133 
                 419 
                 480 
                 380 
                 419 
                 441 
                 435 
               
               
                 m/s), nm 
                   
                   
                   
                   
                   
                   
               
               
                 Thickness @ 100° C. 
                 105 
                 103 
                 111 
                 100 
                 103 
                 127 
               
               
                 (1.133 m/s), nm
Disclosed is a lubricant composition for use in association with a device involving metal-to-metal contact of moving parts, the composition comprising (a) a base stock comprising at least one low viscosity poly-alpha-olefin; (b) a viscosity improver comprising at least one high viscosity poly-alpha-olefin; and (c) a performance additive comprising at least one compound effective to improve at least one property of the lubricant and/or the performance of the equipment in which the lubricant is to be used.