I've been planning to polish my plastic (polycarbonate?) headlights using progressively finer sandpaper and the plastic polish. Then I read that plastic headlights come with a protective layer of something to prevent oxidation or discoloring. Sanding would clearly remove that, unless it's already gone on a 6-year-old car. My headlights are not yellow at all; they just have some scratches and marks on them.

Is it a good idea to sand and polish? Does plastic polish act as a protective coating and if so, how often should I repolish?

 

I'm not sure about the coating part. I wouldn't think ours have it.

I would think a few grades of plastic polish applied with a PC would surely reduce the appearance of any scratches. I've never tried sandpaper, guess I'm chicken for fear that I'd mess them up.

 

I was going to wet sand my headlights over winter break, but decided against it after just using a bit of Meguiar's PlastX. It works very well against anything but the very deep scratches. I'll probably wet sand this spring. I guess it depends on how bad your headlights are, but I'd try just using plastic polish first.

 

I've wet sanded my plastic Foglight lenses and I plan to do so
with my headlights in the Spring.
Its not an easy or fast process, unlike using the plastic polish.
I found that the plastic had alot of stone chips and little sratches
and marks that polish just wouldn't take out.
I kept a spray bottle on hand and started
at 120 and went all the way up to 1800 Grit wet paper, At
the end I was left with very hazy looking fogs, then I used
a highspeed buffing wheel and plastic polish, after that stage
they looked brand new.

The only thing I can reccommend is that you take your time
with each grit, use LOTS of water and make sure
you hit all the areas of your headlights evenly.
Short of buying new headlights this is the only "Free" way to refresh them.

Good Luck.
Markus.

 

Thanks, that's what I'm planning on doing. Here's the write-up I found:

http://www.techguys.ca/howto/polish_lenses.html

Anyone have any info about the putative protective coating?

 

this is the way I did mine and it works great. Here is the link.

http://forums.maxima.org/showthread.php?t=443410

 

Thanks Brinkley, someone in that thread mentioned Meguiar's Polymer Sealant as a good hard protective layer which lasts about 6 months.