I used to sell Leer Truck Caps (or Toppers, depending on your neck of the woods) years ago. We used Mother's [FONT=Verdana,Arial,Helvetica,Geneva,Swiss,SunSans-Regular]California Gold® Pure Carnauba Wax [/FONT]on the painted Gel Coat caps. Awesome stuff; goes on easy and comes off the same way if you just let it start to haze.
We use it on my Dad's fiberglass boat prior to launching each season. When we pull her out, it is really easy to clean the lake crud off before storage.
Mother's has since come out with [FONT=Verdana,Arial,Helvetica,Geneva,Swiss,SunSans-Regular]California Gold® Carnauba Cleaner Wax [/FONT]which is "...[FONT=Verdana,Arial,Helvetica,Geneva,Swiss,SunSans-Regular]designed to be the one-step plan for paint preservation. Cleaner Wax is formulated to clean and protect in just one application. We use the same Brazilian #1 yellow carnauba that makes our Pure Carnauba Wax so special, and combined it with a light polish that will smooth minor flaws and make your paint snap. Carnauba Cleaner Wax is especially effective on fiberglass and gel coats. Available in long-lasting, easy-to-apply liquid or paste."[/FONT]