For stains I had good luck with a diluted orange cleaner made by ZEP. I used it on my motorhome. Try it on a very small spot first to make sure it doesn't hurt the paint. It will take ALL the protection off, so you have to re wax it after. I kept it in a chemical sprayer, diluted, sprayed it on the sides, then washed it right off with car soap and water. Be careful. Test it first.