I was told that Mean Green worked great to remove black streaks and to to clean my aluminum trailer and the white skin.

Reading the instructions on the Mean Green, it says DO NOT use on painted surfaces or aluminum...

Soooo... who has used this on their trailer and not had it damage it?

Or, is there something better? Im not impressed with the local place to acid wash it.

What size would do a 4 horse with a 4 1/2 ft shortwall?