Red Max Pro #3. Available at Lowe's for about $15/gal, and a gallon will do the biggest motor home with lots left over. Check the thread on the Vintage Forum posted above, or this one, the mother thread
Easy to apply, no buffing or rubbing. Gives you a show room shine on the worst old oxidized, weathered fiberglass. Once a year give it a re-wipe to keep the shine..
You will be smile and smile and smile when you're done!
Here are the instructions