Some people like products like NuVinyl and even Armor All.  Others claim
they hasten the premature decomposition of the plastic.

If you already have a mess, then you aren't going to make it much worse
by trying something like this.

I used Armor All on my company car dash some years ago, and never
had any indication of problems.  But, use at your own choice.

I found Armor-all to do a good job of restoring the shine. If the color
is faded though there is not much to do but replace it.