I also use Dawn to wash the exterior as well. For the stubborn black streaks and cleaning the white underside of the awning I use Lysol Power Foam bathroom cleaner in the spray can as recommended by RevJeffrey here on the forum (
http://www.thorforums.com/forums/f8/...-try-8247.html). I also use the Lysol on the roof for really stubborn stains. An added benefit to using the Lysol on the roof is if you put out the awning and rinse the roof so the Lysol & Dawn runs off the passenger side of the roof onto the awning, the top of the awning will also get cleaned (and the mildew and mold will be removed).
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