I work in a chemistry lab at Western Michigan University. To make a long story short, we have been given a nice old vacuum pump. It's a Cenco Hyvac, with a plate on the pump that reads M27922. It consists of a GE 1/6 HP electric motor and the pump unit, both bolted to a heavy iron base. It's all black, and there is no guard for the belt. (Back then, people had enough common sense that a belt guard wasn't necessary.) The oil in it looks good (clear and amber) and everything turns freely, but the pump needs a top up or an oil change. It requires Cenco 11023 vacuum pump oil, which doesn't seem to exist these days. We have lots of Edwards Supergrade A for the newer 2 stage pumps, but I hate that stuff because it's almost impossible to clean up. I sent an email to HyVac, but I thought I'd post here since it's kinda interesting, and I know we have some chemists here. Anybody know what solvent to use to clean up these new pump oils? Are they silicone based?