How do I clean black stains from the sides of a cargo trailer?

It appears that while sitting outside for a long period, my custom-painted trailer now has ugly black water-streaks coming down the sides of all panels. Simple Green/Purple Power/Car Wax all have little effect unless massive muscle-power is used per tiny area. Does anyone know of an easier way to remove these ugly stains?How do I clean black stains from the sides of a cargo trailer?
CAMPING WOLD or most camping supply dealers sells a product called BLACK STREAK REMOVER and it works just great.


Yoiu might even get a simular product at Wall-mart.


Good luck


RonHow do I clean black stains from the sides of a cargo trailer?
you might want to try mr. cleans magic eraser