The first time I saw my 2003 C4S, I knew it was a survivor. The condition of the exterior is excellent with a few rock chips on the hood and just a couple of light scratches. The front bumper had been repainted recently, although the paint match isn't perfect. The seller apologized for the swirl marks on the roof and hood, but I told him those would be easy to buff out.

The biggest cosmetic issue was the very yellow headlights. This car has a wopping 150k of miles on the clock, which meant DD usage with lots of days spent in parking lots. As a DIYer, I know from experience how important it is to find a car that has never lived in cold climates. Rain doesn't rust cars - salt does. But the flipside is UV damage, and the headlights on this car had suffered badly. Of course I used this in price negotiations, but from prior experience with the plastic lenses on my E36 M3 I knew this could be repaired.

Both cars use polycarbonate (PC) material. Bullet proof glass and sunglasses are made from PC for impact resistance, but it hates UV radiation. Acrylic (PMMA) is much more tolerant of UV but is not as tough, which is why it is used for applications like taillights. There are a two big differences between the M3 and the 996. The M3 lenses are vertical, so they get a lot less UV than the 996. For this reason, Porsche applied a thick protective coating. Once this coating itself breaks down from UV, the only way to refinish the lens is to remove the entire coating with wet/dry sandpaper. The E36 doesn't appear to have any coating, so it would yellow pretty quickly (I DD'd that car 20k miles/year). But it was easy to refinish with Meguiars D/A Polish using a 3" foam pad in a cordless drill.

I tried the D/A polish on the 996 and it reduced the yellowing somewhat, but the broken-down UV coating became even more obvious. My car has the Litronic HID headlights with washer jets. The washer jets had eroded through the coating in spots, so the lenses were a mess. See the before picture below:




After reading all the posts I could find online, plus watching a few videos on YouTube, I realized I needed to use some abrasives. I bought a Rain-X kit for $10 at Target. It comes with 3 levels of abrasive pads, which I estimate at 1500, 2000, 3000 grit, plus polishing compound, and lubricant and sealant spray bottles. Starting with the 1500 grit pad, it was obvious this was not enough to remove the factory UV coating. But the Rain-X instructions had some helpful insight. First, always use plenty of lubricant, just like color sanding paint or using a clay bar. (I supplemented with lots of Meguiars Quick Detailer, which Meguiars includes in their clay bar kit.) Second, alternate directions between each level of abrasive, and don’t ever do circular strokes. For instance, go north-south (vertical) and east-west (horizontal) with the 1500 grit pad. Then go diagonal NW-SE and NE-SW with the 2000 grit pad. Then go back to vertical and horizontal for the 3000 grit pad. The only way to remove scratch marks is to go across them. If you go in the same direction, it doesn’t work. This is how you sand out light clearcoat scratches. But the Rain-X method makes it foolproof and effective.

I’ve got a good selection of wet/dry sandpaper at home, so I grabbed some 1000 grit sandpaper, tore it into small pieces folded in half, and then went to work with my bare hands and lubricant. Same result as the 1500 grit pad - no progress getting rid of the factory coating. With 600 grit I finally had some success. The hardest thing about this process was the effort level - you arm will be sore for days after. On the second headlight, I got lazy and tried 400 grit. It removed the coating faster, but when the whole process was done, I could see some scratches from the 400 grit. The only way to remove them now is to go back to 600 grit and start from there. What I did do better on the second headlight is spend more time around the perimeter of the lens. In those areas, the coating had come off on it’s own, or maybe the factory didn’t apply it there in the first place. What looked like broken-down coating was actually microscratching of the base PC lens. Sanding down the microscratching took lots of 600 grit and elbow grease. Here’s a shot after the 600 grit:




After that, I went to 1000 grit wet/dry and my bare hands, using the alternating direction process. Then on to the 1500, 2000, and 3000 grit pads, using lots of elbow grease and lubricant. Once the coating is removed with the 600 grit, the ensuing levels go much quicker. After all the sanding, it looked like this:




Then on to the Rain-X polishing compound. I used my trusty Porter-Cable dual action polisher. (Every DIYer should own one.) It looked pretty damn good at this point:




Now for the Rain-X sealant. I have no idea what this stuff is made from. You spray it onto a paper towel, rub the towel onto the lens, wait a few minutes, then wipe the excess with a clean paper towel. I did two applications, then repeated again the next day. This picture is a few minutes later - I doubt the crystal shine will last for long. But if I was looking to sell this car immediately, I could probably get $2000 more than what I paid. After a full interior detail and D/A polishing the paint, add another $2000. That easy money - or a concours trophy. In my case, look for my car at Legends of the Autobahn next August!




A few other points that I would like to make:

1. I saw videos using a pneumatic sander with a 2” disc. I tried with a 24,000 RPM die grinder and a homemade foam pad with 600 grit sandpaper discs. No luck. I couldn’t keep it lubricated enough, so the paper quickly wore out and the coarse edges of my disc cut into the lens. So I gave up before I had a chance to do more damage. I’m sure a professional detailer would have a power solution, but I suggest DIYers stick with elbow grease. Take your time and do it right. An orbital sander might work, but I think it’s too big and I don’t think 600 grit wet/dry pads are available. Any power tool will leave circular marks, which are harder to clear later.

2. Materials: You’ll need several at least two sheets of 600 grit and one sheet of 1000 grit, plus the Rain-X pad set. Quick Detailer is cheap, so use plenty of it. When you build up white foam, that’s particles of coating and sandpaper grit. Wipe frequently with a microfiber cloth.

3. Prep: Put two layers of masking tape around the perimeter. You want to make sure not to scratch fender or bumper paint with the 600 grit sandpaper. Or you'll spend a lot more time (or worse, paint shop money) fixing it.

4. Maybe you’ll have perfect results after the first try, but realistically you’ll want to try again and get it absolutely perfect. Give it your best effort and enjoy your first attempt. THE KEY PART IS TO REMOVE ALL THE FACTORY UV COATING. Then you can worry about getting the absolute perfect appearance in subsequent efforts.

GOOD LUCK!

 

Looks great! My headlights aren't bad by any means, but I will need to do about an hours of work to each one

 

Excellent work and great write up!

 

My 996 lights were just like yours, I used the 3M headlight kit and they look amazing as do yours.
I pulled the light buckets out and did the work on the bench. Is so easy to remove and install I recommend it next time.

 

Thank you very much for this detailed report. It's the best one I've read especially specific to our cars. When I first got my car, (106,000 miles) I paid a detailer to do my headlights and I was not impressed with the results. Now I understand why. I'll be doing them again myself with the help of your tutorial and I appreciate what you took the time to do by posting in specific detail about this process. Thanks

 

Completely agree on this point. Also, it makes it easier to rinse off the light between each iteration in going to a finer grit paper so as to insure completely removing all residual grit from the coarser paper.

 

It will also completely avoid any sanding scratches on the paint surrounding the headlight if you happen to run off.

 

Obviously I did all this work with the headlights installed. My feeling was that, as much effort as I was putting in, they would be skating all over my workbench. Cutting through the factory coating is not a gentle job - it will take a LOT of effort. your arms will be sore.

As for scratching the fender paint, we are talking about 600, 1000, 1500, 2000 grit wet/dry sandpaper. That's not going to do serious damage to paintwork. A few steps of polish and wax, and it's be just fine. throw your headlight across the garage and break off some plastic tabs, and you'll be crying into your beer.