Shine up your hazy headlights

As people keep their cars longer, oxidation of commonly used plastic headlight lenses is an increasing problem for drivers. Oxidation creates a haze that's not only unsightly but also can significantly reduce headlight illumination, creating a safety hazard. And because hazing occurs over time, drivers might not notice the creeping danger. Hazing can also be more prevalent on vehicles with higher levels of UV exposure.

Replacing the lenses or having them professionally cleaned are options but can cost $200. For a fraction of that, you can use a headlight lens cleaning kit.

We recently sampled four kits—3M Headlight Lens Restoration System 29008, Fast Brite Auto Headlight Restorer Kit, Sylvania Headlight Restoration Kit, and Turtle Wax Headlight Lens Restorer—all costing $21 or less, on several older cars. All the kits remove the cloudy surface of plastic lenses by using abrasives. Three then polish the lenses back to a smoother finish, while a fourth skips directly to the sealant stage to finish the lens. Two other kits also use a sealant. All can be purchased either online or at auto parts and department stores.

We evaluated each kit for effectiveness and ease of use. We used a light meter to measure output from the headlights before and after using each of the products. Then we retested light output from the headlights eight weeks later to see how well the cleanings held up over time. We also noted the difficulty, number of steps, and time required to use each product. Our results varied, but we found that even the poorest performer in our group can dramatically improve light output on badly weathered lenses. You have to do a thorough job, though, for the best results.

A small percentage of lenses have a hard protective coating that must be sanded off before refinishing takes place. One kit, by Sylvania, was able to remove the hard coating with the supplied materials, but the others required us to buy 400-grit emery paper.

Most kits involve several steps for cleaning, as much as an hour for both lenses. One kit, the 3M Headlight Lens Restoration System, also requires the use of an electric drill and sanding discs, but a slip- up during that step could cause scratching of your car's paint.

Bottom line
The Sylvania Headlight Restoration Kit provided the best and longest-lasting results. The 3M kit, though trickier to use, provides similar performance at a lower price. The Turtle Wax kit costs less than half the cost of the top-performing Sylvania. But neither the Turtle Wax nor the Fast Brite, a kit marketed through infomercials, held up as well as the other two.

Listed in performance order.