For just cleaning off dirt, debris, grease, etc. I have always used some old fuel. Then I wash it with soap/water, dry thoroughly, and work in plenty of light oil. I have never tried antifreeze. I have heard that you can get the baked-on varnish off by cooking your engine parts in a crockpot with antifreeze (BUT NEVER use the crockpot again for FOOD!).

But is antifreeze harmful to plastic and rubber parts? I've heard both ways...