They really need to improve the design of this item.  The parts slide together, but are not really attached by catches or threats.  Thus, when you start pumping to create a vacuum, the mechanism wants to come apart.  For greatest efficiency, you need two people; one to hold the unit together and work it, while the other manipulates the hose.  I managed to suck the dirty oil out of my Troybilt mower by myself, but it took more effort than I felt should have been necessary.