The pipes and inside of my 60 gallon air compressor tank are covered with a thick oily film. I'm pretty sure it came from a pump I replaced a few years back. Of course I don't know for sure, but my guess is it's not from the replacement pump. I figure I can clean the pipes out easy enough, but what about the tank? More specifically, does it really matter, is it possible to get clean-enough-for- painting air from a tank that's coated with oil? If I were a younger man, I'd strip the pump and motor off and put 5 gallons of degreaser/solvent in it and roll it around. This is one of my stay at home virus related projects.........installing a condenser system when I found the oily residue on the old pipes.