Headlights, just like every other aspect of your car, have evolved over the years. They used to consist of two or four glass-sealed beams that mounted into a headlight bucket, secured by a chromed metal ring with screws that affixed into three or four separate threaded holes. Over time, carmakers started using high intensity halogen bulbs that, compared to sealed beams, were small, emitted brighter light, and plugged into small plastic sockets that twisted into a main plastic socket in the back of the headlight compartment.
At first this headlight compartment consisted of a small bin that was part of the entire front grille area of the vehicle. Today it has evolved into what is called a lighting assembly that contains the headlight bulb along with the turn signal and running lights, and it is molded of high impact plastic. While this may save on manufacturing costs as well as maintenance, there is one small problem with today's design. The clear plastic that makes up the headlight lens portion of the assembly tends to dull to a yellow milky color over time, drastically diminishing the candlepower of the headlight bulbs and causing poor nighttime visibility.
Polishing The Plastic
How do you solve this problem? It used to be an expensive repair, because the only way to solve the problem was to change entire the lighting assembly, which cost anywhere from $200 to $500 and sometimes more, depending on the year, make, and model of vehicle. You could save money by buying a used lighting assembly, but demand is high, so used assemblies in good shape are hard to find.
About seven months ago I was invited to a Turtle Wax press event. They introduced a new product called a Headlight Lens Restorer. I spoke at length with Michael Schultz, Senior VP of Product Development at Turtle Wax. Schultz, a chemist, explained to me that, until now, this yellowing condition of the headlight lens was impossible to reverse because the plastic lens surface was altered by chemical contamination coupled with road dirt and the effects of UV rays from sunlight. But he and his team were able to come up with a way to alter the plastic surface and restore it to a clear state without harming the plastic.
With the Turtle Wax Headlight Lens Restorer kit, you coat the lens surface with a special lubricating solution, and then you use the three-part rubbing pad portion of the kit. Each pad has a different grit abrasive surface, starting with coarse to remove the rough yellow surface, and leading to super fine grit for finishing of the clear lens. Starting with the coarsest rubbing pad, you rub the heaviest portion of the yellowed area away from the lens surface, then the next pad is used to start the finishing process of the lens surface. Finally, once you're satisfied with the clarity of the lens surface, you use the last pad to for the final finish.
Next, you apply the clarifier to completely clean the surface and then seal the lens surface with a lens sealer solution. When I first saw the process on film, I was skeptical to say the least. Then I went outside and tried it on a 2000 Ford Taurus that had dull and yellowed headlight lenses. The kit effectively removed the yellow surface and the lens was as clean and clear as a new unit. I recommend it if you have yellowed headlights.
Other Lighting Problems
The most basic problem with headlights is that during wintertime, they get dirty. Nothing decreases the effectiveness of your headlights faster than a sudden load of salty slush on the headlight lens. If your vehicle is not equipped with headlight washers or wipers (a few luxury cars are) then you'll need to wipe off the headlight lens with a rag piece of paper towel, often. You can even apply a special glass cleaner such as Rain-X or a similar product to help stop the slush from sticking to the headlight lens.
Another problem is that lighting assemblies get loose due to constant road vibrations. When the lighting assembly vibrates within the vehicle body it causes the headlight bulb to vibrate, resulting in premature failure. If your vehicle keeps blowing headlight bulbs, make sure that the lighting assembly is secure by tightening screws and other mounting hardware.
Lighting assemblies are made of plastic and are supposed to be sealed so that they are protected from environmental factors. However, over time they may crack (or on some older vehicles, a sealing gasket may go bad) and moisture gets into the assembly. When moisture comes in contact with the hot glass of the bulb, the bulb blows. If you see moisture on the inside of a headlight lens, don't be surprised when the bulb fails. Stop the leak or you'll end up investing heavily in new bulbs.