Originally Posted by rcompart
Call me retarded but I've never seen one of those that you use to suck the oil out so I have no idea how you connect an air compressor to it and have it suck the oil out. I've used units before that hold the oil and then you use an air compressor to push the oil out to drain it but never the other way around.
Guess I'm asking in fewer words, hows the damn thing work?
It uses the venturi effect.
Venturi effect - Wikipedia, the free encyclopedia
Basically the air pumped in exits through a venturi, creating a vacuum that is used to suck fluid into the tank.