On vacation last week I happened to notice a number of cars and trucks (all Fords!) that had badly deteriorated plastic headlight lenses. This wasn't water condensation inside the lens housing but some kind of permanent fogging,crazing, or discoloration of the plastic. Some of the vehicles were really cheap Rangers or Escorts, but then I started noticing it on more expensive models as well. Does this eventually happen to all plastic headlights, i.e. like the X's? Is there a way to prevent it?

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How the plastic lenses hold up depends on a number of factors.
First is the quality of the plastic. The manufacturer of the vehicle controls this.
Environment - harsh sun, sandy, salted or dusty roads can haze the plastic.
Driver habits - tailgate other vehicles and the plastic is sure to get pitted from the debris kicked up by the tires.
Vehicle care - washing with non-abrasive products.
Plastic care - There are special cleaners and polishes for plastic. Meguiars, Novus and others make them. I use Meguiars #10 & #17 on the plastic rear window of my ragtop.

dave and xtoy - top down

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[This message has been edited by DaveDatsun (edited 07-25-2001).]

I've seen this too, its not road wear, just plastic aging/fading like from the sun.
The plastic polish may help it.

Kerensky, I think you're right--this looks to me more like UV damage from sunlight than anything else. Because it may be a photochemical reaction, not physical damage per se, it looks to me like it might be happening throughout the thickness of the plastic, not just on the surface, so I'm not sure a polish would do much. Short of squirting SPF50 sunblock on the lenses daily I don't know if anything practical can be done to prevent this. I'll look into it a bit more. Does anybody know offhand what kind of plastic the X's lenses are? The highly sophisticated "tap" test says it's not very thick, whatever its composition.

Thanks for the replies, both of you.
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[This message has been edited by trwinship (edited 07-27-2001).]

OK, not to be overly anal about this but I did a quick Google search and got a surprising amount of information. Most plastic headlights are polycarbonate--not sure about the X but Nissan has used this in the past. It is extremely strong and should be fairly resistant to UV damage, but most such headlights are susceptible to hazing after roughly 5 years--your mileage may vary. I'm given to believe that UV exposure would lead more to yellowing than hazing, and that yellowing occurs more from the inside of the housing out. There are numerous references to people using plastic polishes as DaveDatsun mentioned to fix the hazing problem, so it does work. There were also strong warnings, however, against using products designed to polish vinyl on polycarbonate headlights or other transparent hard plastics.

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