I suggest giving Optimum Power Clean a try. This is a powerful cleaner that, when diluted 3:1, won't harm your paint. I suggest spraying it on the stained area, let it dwell for a minute, agitate with a wash mitt or sponge, and then rinse off.
Extremely versatile product. Can be used on interiors, paint, wheels, tires, and engines. Amazing cleaning power but without harsh chemicals that are harmful to vehicles and people Several dilution ratios making it a cost-effective all-purpose cleaner
www.opticoat.com