I'll probably end up keeping my 98 till the wheels fall off so I'd like to keep it looking fairly good. The paint is black and I have been waxing it semi-regularly with synthetic wax. However, the plastic parts are turning grey and the typical treatments only restore the black color for a few days. Also, the rubber seals around the windows are showing some oxidation.

What are the best treatments for the exterior plastic and rubber parts?

Thanks