My red 99 3000GT has badly oxidized paint, especially on the plastic parts like the spoiler and rear panels behind the windows. Any suggestion on how to wax/polish/buff some shine back?

 

comet cleanser works good

 

Red paint oxidation is always a problem. You can try very fine polish like Griots Machine Polish # 4 or 3. If the oxidation has gone too far the only way to fix it is to have the parts re-sprayed. Sherwin Williams automotive finishes can match the color exactly if you provide them with the paint color number from the metal tag on the firewall under the hood.