If your once-crystal clear headlights now look like they're covered in wax paper, it's safer to learn to clean and buff them up yourself to maintain the life of the vehicle. Learning to inspect the headlights to figure out the degree of damage will help you learn how to approach the task. Then you can learn to abrade the wear and buff them to a new shine.
BASIC HEADLIGHT CLEANING
Prep Wipe as much grime as possible off the headlights with glass cleaner or soap and water. After drying the area, tape around the headlights to ensure you don't end up sanding your car's paint. You can also remove headlights for cleaning, but you might have to align them after reinstallation.
Sand All of these products use an abrasive such as sandpaper to scuff away the outer layer of haze. This is the most important step, so be thorough. When you're done, the entire headlight should be clear of any yellowing and have a rough, dull surface.
Polish A fine polish cleans up the sandpaper scratches and makes the headlight lenses clear again.
Apply UV Sealant There's a reason we tested only headlight lens restorers with a UV protectant. The sanding step removes any protective layer that was originally applied to the headlight, and if you don't reapply that shield your lights will haze over again in as little as a few weeks. Some products, such as the ones from Sylvania and Lenz Solution, promise extended protection.
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Image Source: Behind the Wheel