Trim Restoration with Cerakote Ceramic Trim Coat on my old Bumper. 

Maybe after it's clean use Armor All. I've used that and it worked great. After the AA try your stuff to keep it shiny clean.

I found Turtle Wax Hybrid Trim restorer worked much better it is Black Cream.

👌🏼customer satisfaction or Your money Back ….

Turtle wax hybrid, graphite, trim, restorer that’ll work on your bumper. It worked on my 2011 Mazda.

1987 was 37 years ago. There's no way that car has been in the sun for 40+ years. And unless you're the original owner, it could have been garaged earlier in its life.

You need something with carbon in it. Solution Finish is the only decent product, but it's inconsistent and difficult to apply.

sun: 1 trim restorer: 0

I think it's just too far gone, most likely. It's black plastic, right? I just used Cerakote to fix some "zebra striping" on the black plastics on my 2017 Buick Encore, and it does work -- the black looks great now. But there's also a silver plastic skid plate on the front and back bumper with even WORSE striping, and it barely made a dent in that. I think I'm going to try a heat gun and/or blowtorch on that piece and see what happens. That method seems to work just about every time, but supposedly it can be bad for the plastics in the long run, so you probably don't want to do it over and over again, and you probably want to regularly apply something to protect it after you do it, so that it doesn't continue getting worse.