The streaking is not from the roof; but from the aluminum oxidizing from the TV antenna; air conditioner; and any other aluminum (roof vents) on the roof. The only way to keep the sides from streaking is to divert the water into the channels or gutters. Installing gutter spouts at the ends of all four corners will allow the runoff to drip away from the sides of the motorhome instead of running directly down the sides. You will always get some streaking but at least it will be confined to the corners. Keeping the roof clean (don't park under trees) and washing off heavy dirt at least once a month will keep the dirt from building up.