faded cap

Won't matter what you use it will only be temporary. I buffed out my 5er's cap with some expensive stuff from the local auto paint store using an electric polisher/buffer. Looked great for 6 weeks. It's a common problem with all brands. Just go read about it on any brand forum. Just my guess but there's probably only a few companies supplying front caps for the RV industry. That's the reason why it's not brand specific when it comes to fading.

Painting it is the only way you'll keep it looking new for a long period of time.