Ok, have to admit that I am one of these people that wash and polish the MH after every trip So, after a good rain and all the dust and crap has been washed off the roof down the sides, it drys to leave the black lines. So, what's the best way to get rid of them? The van gas a good covering of polish on, but they still seem to be a little difficult to come off. Would a good coat of wax applied after polishing help? The van does lean very slightly to one side as my driveway isn't quite level, so it's generally only one side that get the lines. Any advice greatly appreciated. Also, is it safe/advisable to stand on the roof? I can reach the front roof light by standing on my porch (see above picture), but am a bit hesitant about stepping onto the actual roof.