My 1995 Nissan Altima headlamp lenses are yellowed and milky. I looked in the other questions but most of those seem to be about condensation… A friend said my problem is due to oxidation and can’t be reversed. Internet research has led me to several commercial products but I’m hesitant to spend $$$ on a useless product. I came across somethng called “Brighteyes” and another by Crystal View Chemicals. I read on the other posts that toothpaste and elbow grease may be the solution- or is that just for fogging and condensation?
If they are as bad as they sound, you’ll need to use ultra-fine grit sandpaper (like 800 or 1000 grit), followed by rubbing compound, polishing compound, and plastic polish. And a very large portion of that elbow grease. Figure on about 30 minutes per light.
I’ve had similar problems on multiple cars and my feeling is that when you clean up the headlights it doesn’t last long-a few months later they look crappy again. I usually just replace the headlights with new ones if it gets bad enough. I figure once ever 10 years isn’t a big deal, although it doesn’t seem to be an issue on some of the newer models. If they’re really bad though you might try a cleaning product-what have you got to lose.
I think it is sun damage. Auto parts stores sell kits for treating the lenses. They contain fine sand paper and lens polish. Make sure you follow the directions precisely.
Are most auto parts sales people educated on this stuff? If they see the car can they recognize it for sun damage? And just out of curiosity, what’s the difference between sun damage and oxidization?
I’ve used toothpaste with good results. The effect is temporary, needing to be reapplied every few months, but a tube of toothpaste costs a whole lot less than new lenses. Also, I have used Meguiar’s PlastX, which works really well. It, too, is only temporary, and must be reapplied every few months. But at $10/bottle, it is also much cheaper than lenses. Plus, I’ve found PlastX works somewhat better than toothpaste. You can purchase a bottle at your local parts store.
Those are good questions. I don’t think auto parts store clerks get that much product training, if any. I could be wrong about it being the sun. It could also be caused by fine road debris, like sand and gravel. Do you mean oxidation? Oxidation usually happens to medal, not plastic. Plastic doesn’t rust. Regardless of the cause, the solution is the same. Either sand and polish or replace.
It is oxidation, but it’s only on the surface. They sell special headlight polishes at eth parts store, but in truth any fine abrasive compound, be it automotive polishing compound (not to be confused with “polish”), or even toothpaste (with “whitener”) will work. I’ve used both lens polisher and polishing compound with equally excellent results. Both are only a few bucks.
I am going to try my luck with a lens polishing compound over the weekend since its only a few bucks and available at any auto parts store. Seems like the debate is more over what the cause is more than the cure… I’ll let you all know if it worked. (And yes, I meant oxidation not oxidization 
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Try using a drill mounted buffing pad and wetting the compound well. Media suspended abrasive work best when wetted. I like the sponge type of buffers if you can find one 'cause they hold the water better.
Use the ultra-fine sandpapers mentioned here until you get a finish you like. Once you’re done with polishing the lenses, spray on a a few thin coats of clear lacquer to protect the finish. Doesn’t last as long as the original factory lenses, but much much cheaper. I’ve done this for years with no ill effects.
I sure miss glass headlamps. Style has won out over function with this issue for sure.