I have a 2000 model Gulf Stream TT and it's been sitting and no one has done much to help the black streaks and mildew on it for years. I've tried several things and one of them is WD 40 but it isn't the perfect answer for all problems. I tried some thing today that worked really good ..TURTLE WAX ...Liquid Clay Bar.... I had a pretty bad mess on the sides front well really all around. I rubbed with just a little pressure and almost all of it came off PDQ.. It also takes off oxidation from the old paint and it even shines now ... I just rubbed it on wiped it off and that's it .. took about an hour to do almost the whole thing.. just missing some of the top where I couldn't reach without a ladder.
Good Luck
Don
If you think the grass is greener on the other side, then you need to water your own grass
