[RJLII]

While driving in Chicago last week I had an 18 wheeler in front of me drive over a big section of patched pavement and sprayed me with tar covered sand and pebbles picked up by the tires. A prompt car wash seems to have taken everything off the paint, but I had little granules stuck to the windshield and headlights. They're like tar coated grains of sand. It took a rag moistened with mineral spirits to get it off the windshield but I'm hesitant to use that on the headlight lenses for fear of crazing or fogging the polycarbonate material.

Anyone have any suggestions as to what I can use that will dissolve tar but not wreck the lenses?

 

[Doug Huffman]

I feel your pain and wish you the best. Your concern about mineral spirits is good, but they are the best. Perhaps a brief judicious application as with a cotton swam and for just a moment then wipe it away.

Once you have recovered, learn about Aqua Pel Glass Treatment. I have used it on windshield glass for many years - since Rain-X was sold and the formula changed. For two years now I have used Aqua Pel fluoroalkylsilane on the whole body of the X5.

In addition to being hydrophobic, as is the effective ingredient in “ceramic” coatings, fluoroalkylsilane is also oleophobic and so effective against petroleum products. It is harder and shines better.

 

[kssod]

Gyeon Q2M Tar

 

[TreyWaters]

For a less harsh treatment than mineral spirits, use some vegetable oil. The vegetable oil will help to dissolve the tar, then you can use soap and water to clean off the vegetable oil.

 

[Joe-BMW]

WD-40 will work as well. Once you get them all off, I would give the lenses a few wipes with Meguires Plastix.

 

[markl53]

Slightly OT, but in general, I am seeing more and more cars with clouded headlight covers. Used to be lower end cars I would see, now seems like all makes, and not that old. Seems like maybe the materials being used just don't hold up well.

 

[Doug Huffman]

Seems like maybe the materials being used just don't hold up well.

It is technically challenging. Quite similar to ageing of tires due to UV exposure. The UV blockers are only skin deep in application and function. The abrasion is similarly just like tire wear. Tires abrade against the road surface and headlight covers are abraded by wind entrained road trash.

 

[FredoinSF]

Slightly OT, but in general, I am seeing more and more cars with clouded headlight covers. Used to be lower end cars I would see, now seems like all makes, and not that old. Seems like maybe the materials being used just don't hold up well.

Exposure to sun and whether the car is properly detailed is going to affect whether the headlight lenses will hold up or not.
A car that is not garaged and only sees automatic car washes will have cloudy headlight lenses after a few years.
If DIY detailing the car, apply same treatment to headlight lenses as for the paint. I use clay and wax at same time as I do for paint. Given I hand wash my cars I seldom need to polish, but if I polish the paint I also hit the headlight and tail light lenses.

Pictures to prove my theory. Below is my 20 year old E46 that I've had since new. Headlights are clear.

And my recently acquired winter beater Jeep that had never been detailed with a 'before' of the front end coming home from driving in a snow storm over Donner Pass and the 'after' a few days later after a six hour detail / paint correction with clay polish and wax. The headlights look new.

 

[RJLII]

I stopped by my local dealer and they got me fixed up. They had a plastic safe anti-static cleaner they soaked a micro fiber cloth with and that took the tar off.

I'll echo what @FredoinSF says above. Take care of your lenses and they'll take care of you. I either use Plexus (Plexus Plastic Cleaner for Automotive Uses) or a similar product from Honda intended for Acrylic and Polycarbonate bike windshields. My old 328d had 108K on the clock after 8 years and the lenses looked like new.