Originally Posted by Duke2.6

I use Pledge furniture polish - the traditional unscented type. Pledge is an emulsion of carnuba wax in a petroleum distillate. The wax seals up the surface of the vinyl and prevents it from outgassing - what we know as "new car smell". Over time heat causes the vinyl to outgas, which shrinks it and builds up stress. Eventually the stress will cause a crack. The carnuba wax leaves a satin finish, which is not too shiny or slippery. It can be used on any vinyl surface in the car including the door trim and MB Tex seats. It's probably good for leather, too.

A surface sealant and keeping the dash cool by covering the car when it's parked outside is your best long term protection. UV damages organic materials by breaking down the molecular structure. That's why clear coats break down and paint pigments fade, car covers disintegrate and people get skin cancer from too much sun exposure. Most covers will block about 99 percent of solar UV radiation, just like wearing a shirt keeps you from getting sunburned.

Duke