Why do headlights turn to a yellow haze?
Like all plastic and rubber parts on your vehicle, exposure to the ultraviolet rays from the sun will eventually lead to a break down of the part through the oxidation process. Further exposure to harmful elements such as air pollution, road salt, oils, chemicals and harsh cleaners can also expedite the breakdown of plastic headlight lenses.
BMW sprays a UV protective film over the plastic lenses to slow down the oxidation, however, if you park your car outside or expose it to harmful elements, it is inevitable that your headlights will turn yellow. We will teach you how to avoid this unsightly and unsafe issue to prevent costly repairs in the future and maintaining a proper look of your vehicle.
Headlights and important safety feature during the night and harsh weather conditions. It is just as important to maintain headlight lenses as it is your engine to ensure longevity and safety.
Why doesn’t BMW just use glass headlights like the good old days?
Glass is much more expensive than the plastic alternative. Most car owners today do not plan on owning their vehicle for 200,000 miles of use like most owners were in the 1980s. Modern-day vehicle owners (or leasers) are buying new cars every 3-5 years. Because of this, a permanent solution to hazey headlights is not needed. BMW manufactures millions of vehicles a year and can save millions by offering “temporary” plastic lenses which will last the now shorter lifespan of newer vehicles.
Headlight design is becoming one of the few features that allow freedom of design for manufacturers without being overly restricted by government regulations. Plastic lenses allow for the manufacturability of unique and complex shapes compared to the limited manufacturability glass lenses.
Additionally, glass lenses are a hazard when broken in an accident. Pedestrians hit on the road, other vehicles may run over broken glass headlight lens, animals crossing the road are all threatened by broken glass shards. These threats can all be prevented by using plastic lenses.
What are the downsides of yellow haze headlights?
- They look disgusting.
- It makes your car look old and unkept.
- They prevent proper road visibility at night and during inclement weather.
- It is harder for oncoming traffic to notice you.
If you already have clear lenses and want to prevent the future threat of yellow lenses we highly recommend clear vinyl wrapping the face of your lenses. Clear vinyl will not only act as a barrier to rocks chipping your lenses but they act as a barrier between the exposed plastic lens and UV rays from the sun. Clear vinyl can be wrapped around intricate shapes and is a solution to all types of headlight designs over the ages of BMW models.
You can find clear vinyl on Amazon or eBay for a very cheap price (around $6 for a sheet 1 x 6 foot). You do not need a professional to install it, it can be done at home with a heat gun and soapy water. The best part is, if you screw up, you can peel off the vinyl and start over. The process is completely reversible and for how cheap the material is, you have nothing to lose and everything to gain.
An alternate option to clear vinyl is to apply UV spray over the lenses. Meguiar’s makes a 4oz bottle of UV headlight coating for around $9. If you live in a hot climate near the equator where UV rays are more direct, you want to apply it more often than northern climates.
How do I fix my already yellowed headlight lenses?
E21 / E30 / E28 / E34 owners:
Rejoice! You have glass lenses and will not have this problem. You can still apply clear vinyl on your lenses to prevent rock chips and pitting.
You have sealed headlight assemblies and cannot replace just the clear lens. New headlight assemblies can be purchased new for about $90 each. The best solution is replacing the entire assembly with brand new assemblies, then applying clear vinyl for a lifetime solution to the problem.
OEM BMW E36 left headlight assembly part number: 63121387861
OEM BMW E36 right headlight assembly part number: 63121387862
Another option is to find glass headlights from Europe. People will post these on eBay or Forums from time to time. Depo makes OEM replicas with glass lenses that is also another permanent solution. These can be found through online parts suppliers via a simple google search, "E36 depo headlights". Even if you buy glass lens headlights we recommend clear vinyl over the front to prevent rock chips from pitting the lens.
A final, but least recommended, solution is to sand the yellowing oxidation off the lens and apply clear vinyl. This is for the true budget conscious owner but definitely not the best solution when you have the best option of glass lenses. It is hard to get the lenses perfectly clear and the headlights are prone to oxidation again in the future.
E46 / E39 / E53 X5 owners.
You have the best option of them all. BMW had the best headlight design with these models, by allowing the replacement of just the clear lenses without having to replace the entire headlight assembly. New lenses can be purchased for around $85 each side. Depending on early or late model, xenon or halogen the lens part number will be unique to your vehicle. We recommend going to realoem.com to get your OEM BMW headlight lens part number then using google to search a vendor for that part number. Vendor websites such as FCPeuro.com also will display these replacement lenses once your input your vehicle make and model.
Once the headlight lenses are replaced, we highly recommend applying clear vinyl over them to create a barrier between the plastic and the outside elements, eliminating the possibility for yellowing in the future.
E9X / E60 and later owners:
This is where BMW started to go downhill with design for headlight maintenance. The lenses themselves are not replaceable, you have to replace the whole headlight assembly which is very costly (especially for xenons). Your options are to replace the entire assembly (ideal) or to sand off the oxidation and cover the newly exposed surface with clear vinyl or UV spray to prevent it from happening again.
Why does just sanding headlights only work short term?
Sanding the headlights look fantastic for the short term. You are literally removing the oxidation and exposing a fresh layer of clear plastic. The problem is, this plastic is now exposed and unprotected from the sun and other harmful elements. Oxidation will set in much quicker and lead to yellowing within months usually. If you sand the lenses, remember to protect them by applying vinyl or UV spray.
What are headlight alternatives I should avoid completely?
Avoid all aftermarket (eBay) headlights. These are not only assembled using very cheap plastics and age quickly, they aren’t sealed as good as OEM lens and often leave moisture trapped on the inside of the lenses. Don’t waste your money.