Time will tell on how well it lasts and stays on but I've used rattle can bed liner on the wheel housings on my wifes Tahoe. So far, about 8 months later it still looks good but it does add texture where there used to be none.

One product that also works very well but does not last super long on the plastics is Blak (find it on amazon, spelled that way). The stuff works great on tires and seems to last longer on tires. Not glossy once dry either.

 

To get that plastic back to black, try Gtechniq C4 Trim Restorer. Creates a deep black look, that lasts (according to the manufacturer) up to 2 years. I just used it... looks great... longevity remains to be seen.

 

Its been some time since I freshened up the frame and it still looks good. I have been trying products without success on the black trim parts but without much luck. I have purchased Cerakote but have not used it yet. It seems to work nicely on the trim parts on my 2500 but that is a 2019 and not a 2008 that has seen weather. I have read many reviews, both positive and negative. One thing is for sure once you put it on its nearly impossible to get off so you better be sure its gonna work.

Anyway, I have included a picture of Cerakote and am asking the members of the forum if anyone can share the results. 2 Things are for sure, first I don't want to ruin my trim parts and second the thought of removing them to have them professionally painted is also not an option.

I have tried 303, Mothers Back to Black, Mequires Ultimate Black, Solution Finish Black, Adams Black, Chemical Guys Black on Black and Groits Black Shine Trim restores, all of them with various degrees of success but none of them last more then a few weeks in the New Mexico sun and altitude.

The unfortunate thing about the Cerakote is it appears it all comes down to who originally made the plastic trim parts and the compounds they use. I would love to find a fellow H2 user here on the forum that can say thumbs up or not on this product. I also added a picture of the Cerakote on my 2019 2500, this is about 6 months out but again this was applied to a non-weather trim part.

 

I've tried many trim restoration products and none work well long term. I painted all the exterior trim with SEM trim black 2 years ago and still looks great. I removed all the pieces except rockers. The finish is perfect satin.

 

You are doing it wrong with those magic liquids, none of which works. Those are temporary products, which last from days to weeks, to maybe a few months.
They are made by well-known-names but are all an expensive scam.

What does work, and extremely well, is "plastic dye". And it is permanent.

I dyed plastic engine panels on a Lambo that turned gray and the black plastic bumper skins that did the same on the H2, and that was years ago. Still holding up fine.

Problem is, that the company that made the goo I have is out of business.

The material is not actually a "dye". You can not dye plastic. But it is a rub-on translucent coating which permanently adheres to the plastic.

Find the black plastic dye somewhere on the internet. When you do, please share the source here.

The other options are no bueno. One is full-on-paint, but that peels off and has other issues. Especially on plastic. Like the one pictured above. Sure it looks new and shiny when new. But wait a bit.
I prefer the OEM look you get with the dye. And it does not peel off. If scratched, it does not behave like paint.
My experience with Cerakote on guns is that it wears off quickly. And then look like a*s.