What the Texas sun does to your lenses, and what it costs you after dark.
Since the early '90s nearly every vehicle has shipped with polycarbonate headlight lenses instead of glass. Polycarbonate shrugs off gravel that would shatter glass, but it can't handle sunlight. A thin factory clear-coat is all that protects the lens from UV, and that coat wears out.
The standard on most trucks and cars on the road today. Plastic lens, replaceable bulb behind it.
The brighter arc lighting on many 2000s-2010s vehicles. Same plastic lens out front.
Modern and efficient. The lens covering it is still polycarbonate, and it still fades.
UV radiation breaks that factory coating down a little more every day the vehicle sits in the sun. Once the coat's gone, the bare polycarbonate oxidizes: yellow first, then cloudy, then chalky. Heat and road grit speed it up. Most vehicles parked outside show visible fading within a few years.
A clear lens focuses light into a controlled beam down the road. An oxidized lens scatters it. Low beams reach shorter, the cutoff line goes fuzzy, and part of your light ends up glaring at oncoming drivers rather than lighting your lane. Out here that shows up on unlit county roads, in the rain, and during deer season.
New headlight assemblies run several hundred dollars a pair, more for LED units. Restoration strips the oxidized layer and takes the lens back to clear for a fraction of that, right in your driveway. If your lenses look yellow in the daylight, that's oxidation, and it's fixable.
