Why does my Cherokee PA28-180 Lycoming motor run hot?
You say it runs hot.  Why do you say that?  Is the oil temp pushing redline?  Do you have a CHT gauge?

EGT alone means nothing. Don't use it to set cruise settings.  What if the probes aren't all set 5&quot; (or whatever) from the exhaust valve? What if they're only 3&quot;?  Or 7&quot;?  Or staggered between 3&quot; and 7&quot;?  Point is, the EGT number is just a repeatable value.  Don't think of it as a temperature.  Your Archer with probes 5&quot; from the exhaust valve may read 1350° at full rich takeoff from sea level.  Your hangar mate with an identical plane (except for having probes only 3&quot; from the valves) might see 1420° at the exact same setting.  Once you understand that EGTs aren't really temperatures and are merely reference numbers (or some type of &quot;heat unit that isn't 'temperature'&quot;) the whole thing makes more sense.
Also, if you just have a single point EGT then just pretend it's not there and simply use the POH.  Single point EGTs tend to do more harm than good, especially if they're reading the confluence of two cylinder exhausts.  What possible useful information can you glean from an averaged temperature from half the cylinders on your engine, especially if it's carbureted?!?!

Does your mechanic know (and can he explain) why his tips make sense?  I'd love to hear his reasoning because I don't think it'll make sense.

You either have a bad oil pressure gauge or your pressure it too low.  Fix that.  A good gauge running below red line is very bad.  A bad gauge is better, but still bad.  The limits are not arbitrary.

Engine RPM limits are important.  Does Lyc publish a limitation between those RPMs for your specific engine suffix and serial number range?  If the limitation is an AD, has it been complied with and the limitation removed?
Running your engine at redline will not hurt anything provided the engine does not have a limitation (in the limitation section of the POH) on max RPM.  I know it feels right to &quot;baby&quot; the engine but there is no practical effect unless a limitation exists.  Note that &quot;recommended procedures&quot; are not &quot;limitations.&quot;


I'd seriously consider talking with another mechanic if that's at all practical.  Your mechanic may be an airframe god but his advice regarding engines would have me shopping for a new IA.