Peanut butter definitely won't work on that. And yes peanut butter does work on oxidized black trim because of the oils in it, however that's on faded trim, not cracked. The only resolution for that is replacement. I have a first generation Cruze (2011) and have lived as far north as the snow belt, and has far south as the beaches of Florida since owning it, and my trim is nowhere near like yours is. In fact it almost looks the same as when I got it maybe with some slight streaks in it. Your profile says you live in Virginia which is pretty stable climate. I just don't understand how that happened to your trim. I'd say it is defective but of course probably out of warranty.