my personal opinion, but theres really no way to protect these plastic mouldings as they sit...
they're unpainted, so dont have any protection from the sun.
the only real way to keep them good is to paint them....... either mask up the panel arround them, rub them back with some fine paper and paint them with a preasurepack, or remove them, take them somewhere to be pro painted and replace...
ive done it to my fairlane by masking the panel up, and IMO they came up pretty good..
they'd started to go light grey/white due to the sun
i used a metalic gunmetal preasurepack can, and masked the panels up with tape/newspaper.
i also did the B pillar trims and door handles in the same way with the same paint
heres the end result
http://img.photobucket.com/albums/v6...8/DSCF6059.jpg
and an old pic to see the difference
http://img.photobucket.com/albums/v6...ights016-1.jpg