I use a cleaner called awesome, it works really well in getting mildew/grime off without being too detrimental to the article your cleaning, it and a soft brush will clean it up, just make sure and put some kind of protectant, again i use black majic protectant to add a little moisture back and keep things from drying out on seats and things. As for the Awesome on fiberglass and such it doesnt seem to strip the wax or dull the finish and be as harsh as other cleaners. Just my .02