I first used Zep on my 2002 Hurricane, which was dull and oxidized pretty bad. It was a bit of work to get it cleaned up, and ready for the 4 coats of Zep, but couldn't be happier with the results. Motorhome was parked outside year round, and the Zep held up very well. I gave it 2 coats the second year, with only a good wash before applying. Held up very well. Applying the wax is SUPER EASY, I used a microfiber cloth over a sponge, very thin coats. Sold it the third year, on the first day it was up on craigslist. It looked Great.
My recent use of Zep is on Painted fiberglass with the clear coat worn off. I'm not sure how it will hold up, but application is so easy, I plan to give it a couple coats yearly