I use spray 9 and the magic eraser. This works like a dream on my www. The white walls never looked so good and it's so easy I feel guilty. Got the tip here on the forum.
Home Depot or Loews carries Krud Kutter products in the paint department, get the type for cleaning aluminum gutters and white house trim. Spray it on keep it wet and use an angled scrub brush. Works great and cleans rims too. Krud Kutter in the red bottle removes stubborn goo and grime and is strong enough to soften latex and other paints good stuff for sealant removal and paint prep.