We have a 2003 Class C fiberglass and it was duller than dull from setting outside I guess. Nothing I tried made the slightest difference even an expensive product recommended by the manufacturer. Then I discovered Zep wet look floor polish. Clean thoroughly and just wipe on 5 or 6 easy coats of Zep with a sponge. No wiping off or buffing; just re-coat once a year. It shines really well and is easy to wash. I'm not going on record as recommending this because it is a floor product. All I can say is that I personally have not seen any negative effects on the finish after 2 or 3 years. About $25 at Lowes or on-line.