Some of the old drills I've started picking up have years worth of grease, grime, and general crud built up on them. I remember that my dad used gasoline to clean that sort of stuff off of anything made out of any type of metal. Naturally, I'd rather not use gasoline today, and I don't think that would be a good solution for handles or anything else made of wood anyway. So far I've been using denatured alcohol to clean both wood and metal parts, but I wondered if there are better methods -- effective, nontoxic, non-flammable. What do you use? Note that I'm not talking about rust -- that's a different problem -- just grease, oil, dirt, grime, etc.