^^^ Quite true - enamels like Chrysler used - especially the light metallic colors, like Dad's '66 Sport Fury - oxidized ("faded") in gloss a a few years if left outside.
Some pigments were of course better than others - reds would oxidize quickly but seemed easiest to bring back.

I remember the revelation when ArmorAll was introduced - prior to that, Lemon Pledge was popular, and I can recall someone wiping brake fluid on tire sidewalls.
There was a somewhat greasy/oily product out there back in that time period, but I don't know what it was - I thought it was creepy...