My experience with the 3M headlight cleaning kit
 

The X's headlamps were really foggy/yellow, i've seen worse, but these were pretty bad. I figured it wouldn't hurt to try to polish them, can't do any more damage to them than nature has already right?

I used the 3M kit that included their green body tape.
http://stevedu.com/FSpics/X5/HLkit.jpg
http://stevedu.com/FSpics/X5/HLkit2.jpg

Instead of taping around the body and working on the housing while it was attached to the body, I opted to pull it out halfway. Pulled off the lower trim, removed all the fastening bolts and pulled it out maybe an inch or two. placed terry clothes all around the body panels/bumper and taped the rubber gaskets.
http://stevedu.com/FSpics/X5/HLprepped.jpg

First step, 500grit. I ended up going through 3 pads to get all the imperfections pretty much gone. In the first pic i had taken one pass and you can already see what was rough from yellowing and what was still sort of clear.
http://stevedu.com/FSpics/X5/HL500.jpg
http://stevedu.com/FSpics/X5/HL5002.jpg

Second step, 800grit. Used 2 pads
http://stevedu.com/FSpics/X5/HL800.jpg

Third step, 3000grit + water, about 10 passes
http://stevedu.com/FSpics/X5/HL3000.jpg
Third step, dried
http://stevedu.com/FSpics/X5/HL30002.jpg

Fourth step, rubbing compound. Went over the lens 3 times.
http://stevedu.com/FSpics/X5/HLpolished.jpg

Cleaned and reseated all the gaskets (half of the gasket that runs along the bottom of the headlamp and the top of the trim had fallen behind) put everything back in place according to the marks I made on the mounting tabs.
http://stevedu.com/FSpics/X5/HLcomplete.jpg

The difference
http://stevedu.com/FSpics/X5/HLcomparison.jpg

Took about 2 hours to do the drivers side (disassembly, prep, polishing, cleaning up) and tomorrow I will complete the passenger side. Hopefully on monday my plastix comes in and i'll put a coat of that on it. Final thoughts...definitely a HUGE improvement, it's still not perfect, but I couldnt have wished for anything better for the price. I am curious how it stands the test of time, anyone have ideas about how to keep the yellowing from coming back?

Clear coat would help for a while I assume,I read it somewhere.

I used this kit: Headlight Restoration | Headlight Cleaner
It worked very well and took less than 30 minutes for both headlights. I liked this kit because it comes with a sealant to apply after you are done removing the hazing.

It looks like you did a good job on yours!

Heh, you spend 30 minutes to do both. Makes me feel like i wasted half my afternoon ;-) but i'm happy with the results. Super smooth, now just need to seal it somehow. Maybe i can pick up some of the sealant from that kit you used on its own.

Nah, no time wasted. Your headlight looks great! I think you could probably find some sealant if you do a google search. Or like you said buy one of the kits and use it. I bought mine off of ebay for less.

The second one will go faster--learning curve.
I did mine this fall and was very pleased with the results using the 3M kit. I put Liquid Glass on top to try and protet the lens.
Bill

Looks good. :thumbup:

I used the same kit as XZX54.4 and had success as well.

thanks everyone! I ended up putting a heavy coat of McGuiars NXT techwax 2 on both the lenses since that came recommended after using the McGuiars sanding kit. Since i had it on hand i figured i'd use it. Now that the passenger side is done, she looks a lot less like her 8 year old self.

Hey Duboy,
I also used the 3M kit on my X. It took me about the same time as you to polish one headlight. The other was replaced after a fender bender and was brand new, so I thought I'd try to restore the original(2003) hazy head light (that looked worse than yours BTW) as best as I could. I doubted that the end result would be good, so I was planning on buying some light-smoke 3M vinyl lens covers to mask the difference in the headlights. To my surprise it came out so well that family and friends weren't able to tell unless they payed very close attention.
Your pics seem to show that got great results also!
FYI, I never did buy the vinyl lens covers, and never treated the restored lens with any product. It's been just over a year now and the restored lens still looks great compared to the replaced one. My X is never garaged and sits exposed to the elements 24/7.
My point is: Don't worry. the headlight will stay looking good.
If anything, buy the polishing compound that came in the plastic pouch with the kit. 3M sells it in a bottle and recommended using it to keep any haze from returning. I left the bottle in FL so I can't give you the name. But to find it, I called the 800 number on the back of the kit, and the rep was able to find the polishing compound product number for me. (never did use it on the restored headlight :D)

Great results:thumbup:

How to keep it from coming back? Simple answer is to clean them everytime you wash. Most ppl don't bother with thier glass (headlights, windows, mirrors) but I do and none of my cars have that issue.