The best stuff I've ever used that is not harmful to painted finishes, polished aluminum or my own skin is Mirachem Cleaner Degreaser. And it's NASCAR approved . . . whopee! What really sold me on the stuff is it removes that stubborn yellow varnish stains from gasoline. Spray it on, let it foam up and wipe it off. It really works. In addition, it's water soluble. There's one problem other than it's pricey. The stuff can be hard to get, but you can get information on their web site;
http://www.mirachem.com/