What cleaner do you use to remove the black (brown) streaks coming down the top of the 5th wheel? I washed the rig today and was able to get rid of some of them with the RV soap but there's some stubborn ones that will need more attention.
George & Nancy, Allen, Texas
2015 F350 CC, DRW, LB, Platinum Edition
2018 Cedar Creek 36CK2