3M Paint Buster Hand Cleaner

This is great stuff. Works on one and two-part paints, caulking, adhesives, etc. Expensive, but worth it.

You should always wear nitrile gloves when painting. But when you don't, this stuff will clean your hands of paint and varnish without irritating or drying out your skin. It has some pumice in it, so it's slightly abrasive to remove cured paint. It will also remove uncured paint from clothing. It comes in a very handy plastic tube, which you can stow just about any place. I've found the orange/citrus cleaners to be good for grease, but not paint. This 3M product is good for paint, but not grease. You'll need to use something else after working on your engine. It's expensive -- ridiculouly so -- but a little goes a long way, and a single tube should last a while.