Mother's Back to Black is great stuff. They also make a cleaner that you put on and scrub. Works great to get grease, wax or other things off your fender flares. I would use the cleaner and then follow up with the protectant. I have used that combo many times with great results. They are also available at most auto parts stores.
Dont use back to black or any of the stuff like that it only lasts a short time and it ends up making them worse over time. A degreaser should take it off and then use something like carpro cquartz dlux that will last over a year.
I'd likely hit it with my all purpose cleaner if that didnt work I'd use my megs degreaser diluted down and last effort I'd try a plastic/rubber cleaner I've got then I'd use cquartz dlux for a longer term fix.
I know this is a really old thread, but what works wonders for me on cleaning the flares is olive oil. Yep, you heard that right, everyday ordinary olive oil. Extra-virgin not necessary. Works like MAGIC. Restores the flares to looking like new (honestly). Just a little bit goes a long, long way. Plus it lasts a long time. Works on any black plastic even the bumpers and the windshield wiper trim. Have not tried it on anything inside the interior, but it probably would be just as effective. However I haven't tried it there only because I didn't want my Jeep to smell like an Italian restaurant.
Neil,
Good point, however we have a pretty large rabbit and squirrel population and never have had an issue. Just a couple drops covers half the flare.
At least it's biodegradable with no hard to pronounce chemical additives. If the critters do lick it, it's not going to kill em. Crap that may be a very good reason to use the tire shine poisons.
Just kidding. Try it, it's not like it sounds. It really does work. And no I don't own olive stock.