My 2000 Lincoln Town Car has 150,000 miles and 9 years of wear and tear on it. That has taken a toll on the plastic headlight units on the car. Rock chips, scratches along with yellowing and fading of the lens has reduced the light output to almost nothing. I could probably see better if I held a flashlight out the window.
After researching the cost of replacing the lenses ($150 + each) I decided to try a headlight restoration kit. There are many to be found online, but being impatient I ran to the local O'Reilly auto parts and bought a 3M kit that they had there. Total cost with tax, about $21.00.
I should have taken pictures of the passenger side light as it was the worse of the two, but the though only occured to me as I was working on the drivers side.
I should note that all work was done using a hand-held cordless drill with sanding pads attached to a rotating wheel.
This is the drivers side lens yellow, scratched and pitted before restoratuon. While there are lots of cars out there with much worse headlights, this was bad enough that the look and reduced light output were making it very difficult for me to see at night. I could barely tell the difference between regular and high beams, not to mention that I could not see where I was going.
Step one, lens is sanding using a 500 grit paper removing yellowing and scratches. Left picture has 1/2 lens done so you can see the difference. Right side has entire lens sanded leaving it completely useless at this point. Certainly cannot quit now unless I want to buy a new lens.
At this point lens has been sanded with 500 grit, followed up by 800 grit (both dry). Lens looks pretty much the same so no need for another picture, but as you move up in grit scratches get smoother and softer. Lens is finally polished with 'plastic polishing compound' on a sponge pad. Lens finally comes clear and starts to look good again. I will polish one more time by hand using the 'plastic compound', but even if I dont all yellowing and haze is gone. Headlight output is as good as it was new.
Before (left) and after (right) pics for easy side by side comparison. Note that passenger side was substantially worse than drivers side for some reason but now looks good as new. These pics are not the greatest clarity as they are cell-phone pics, but you get the basic idea.