Roof treatment

[OldCoot]

What is everyone using on the roofs to eliminate/prevent the black streaks coming down the sides? Both for EDM/rubber/whatever.

[Wiscampsin]

I've been using Protect All Roof Cleaner and follow up with Protect All Roof Treatment from Camping World on our last 3 campers with good results. I realize there are people that use Murphy's Oil Soap and a bunch of other products but I'll stick with what's been working for me.