Are there sure fire signs of paint being heavily oxidized versus the paint just fading? One of the doors on my dad's car is looks pretty faded, and I'm sort of thinking it has something to do with the wax not being completely buffed over the years and the sun baking it. I want to fix this *if* I can over Thanksgiving, so I need some advice on which type of product I should use..... if any. I plan on trying a claybar that I have to see if that helps any.