Here's some more info. There's many threads addressing this common topic.
Many of us have tried a product called "Restore/Refinisher". it's not a treatment but a permanent coating, almost like a coat of clear nail polish.

Here's the thread talking in detail about it, and my post #33 explaining exactly how I applied it. And my post #51 provides some updated info since I applied a 2nd coat this year. I did discover a down side, that is, it chips off when abraded, like from a bush or tree branch.
http://vehicross.info/forums/showthr...inish+restorer