How to Clean Headlights with WD40: A Method That Actually Works (Sometimes)

I'll be honest with you right from the start – using WD40 to clean headlights is one of those automotive tricks that sits somewhere between genius and questionable. After spending way too many weekends tinkering with cars and trying every headlight restoration method under the sun, I've developed some pretty strong opinions about this particular approach.

The first time someone suggested spraying WD40 on my foggy headlights, I thought they were pulling my leg. But here's the thing – it does work, sort of. The key is understanding what you're actually doing to your headlights and whether it's worth the trade-offs.

Why Your Headlights Look Like They've Seen Better Days

Modern headlights are made from polycarbonate plastic, not glass like the old days. This plastic is tough, lightweight, and shatter-resistant, which is fantastic for safety. But it has one major weakness: UV radiation from the sun breaks down the protective coating over time, causing that milky, yellowed appearance that makes your car look ten years older than it is.

When that protective layer starts to fail, the plastic underneath begins to oxidize. It's not just a surface issue – the damage goes deeper than you might think. This is where WD40 enters the conversation, and things get interesting.

The WD40 Phenomenon Explained

WD40 isn't actually a cleaner. It's a water-displacing spray (that's what the "WD" stands for) with petroleum-based solvents. When you spray it on oxidized headlights, those solvents temporarily fill in the microscopic pits and scratches in the plastic, creating an optical illusion of clarity.

Think of it like putting water on a scratched CD – suddenly it plays again, but only until the water evaporates. WD40 works on a similar principle, except it takes longer to evaporate and leaves behind a thin oily film.

I discovered this accidentally while working on a friend's beat-up Honda Civic. We were trying to fix a stuck headlight adjustment screw and oversprayed with WD40. The foggy lens suddenly looked crystal clear. We were amazed – for about two weeks, until it looked worse than before.

The Actual Process (If You're Determined to Try This)

Since you're probably going to try this anyway, let me walk you through the least destructive way to go about it. First, clean your headlights with regular soap and water. Get all the bug guts, road grime, and whatever else has accumulated on there. Dry them completely – this is important because WD40 and water don't play nice together.

Shake the WD40 can well. Those solvents need to be properly mixed. Spray a light, even coat across the headlight lens. Don't go crazy here – more isn't better. You're not trying to drown the thing.

Now comes the part most people skip: buff it out with a clean microfiber cloth. You want to work the WD40 into the surface while removing the excess. Use circular motions, applying moderate pressure. The headlight should start looking clearer almost immediately.

Some folks stop here and call it a day. But if you want this to last more than a few days, you need to apply some kind of sealant or wax over the WD40. This helps lock in the temporary clarity and provides a barrier against the elements.

The Uncomfortable Truth About This Method

Here's where I might ruffle some feathers: using WD40 on headlights is basically a band-aid on a bullet wound. Yes, it provides instant gratification. Yes, your headlights will look better for a short time. But you're not actually fixing anything.

In fact, you might be making things worse. WD40 can attract dirt and dust, creating a grimy film that's harder to clean than the original oxidation. The petroleum solvents can also accelerate the breakdown of any remaining UV coating on your headlights.

I learned this the hard way on my own truck. After multiple WD40 applications over several months, my headlights developed a weird, splotchy appearance that no amount of cleaning could fix. I ended up having to do a proper restoration with sandpaper and UV sealant – something I should have done from the beginning.

When WD40 Makes Sense (And When It Doesn't)

There are exactly three scenarios where I'd recommend using WD40 on headlights:

You're selling your car tomorrow and need it to look good for photos. The temporary improvement might help you get a better price, and the long-term consequences become someone else's problem. (Ethically questionable? Maybe. Effective? Definitely.)

You're in a pinch before a night drive and need every bit of light output you can get. Safety trumps everything else, and if WD40 gives you better visibility for that one crucial trip, go for it.

You're dealing with very light hazing on relatively new headlights. Sometimes a quick WD40 treatment can buy you a few more months before you need to do a proper restoration.

For anything else, you're better off doing it right the first time. A proper headlight restoration kit costs about the same as a couple cans of WD40 and actually addresses the root cause of the problem.

The Better Alternative Nobody Talks About

If you want a quick fix that's slightly less problematic than WD40, try toothpaste. I'm serious. The mild abrasives in toothpaste can actually remove light oxidation without the chemical concerns of WD40. It won't last forever either, but at least you're mechanically removing damage rather than just hiding it.

The process is similar: clean the headlight, apply toothpaste (the regular paste kind, not gel), buff in circular motions, rinse, and dry. It takes more elbow grease than WD40, but the results are more honest.

My Final Take on This Whole Debate

After years of trying every headlight cleaning hack imaginable, I've come to a simple conclusion: there are no shortcuts to proper maintenance. WD40 on headlights is like using duct tape to fix a leaky pipe – it might work temporarily, but you're not addressing the real issue.

If your headlights are foggy enough that you're considering WD40, they're foggy enough to deserve a proper restoration. Yes, it takes more time. Yes, it requires buying the right materials. But the results last for years instead of weeks.

That said, I keep a can of WD40 in my garage because it's genuinely useful for about a hundred other things. Just maybe not for headlight restoration. Unless you're in a bind. Or selling your car. Or just curious to see what happens.

Look, we all make questionable decisions when it comes to car maintenance. I once tried to fix a exhaust leak with aluminum foil and metal tape. It worked about as well as you'd expect. The point is, sometimes these temporary fixes have their place, as long as you understand what you're really doing and what the consequences might be.

So if you decide to spray WD40 on your headlights after reading this, at least you're going in with your eyes open. Just don't say I didn't warn you when you're out there with sandpaper six months from now, doing the job properly while muttering under your breath about internet car tips.

Authoritative Sources:

Chalmer, B. J., et al. Automotive Plastics and Composites: Materials and Processing. William Andrew Publishing, 2016.

Kutz, Myer, editor. Handbook of Environmental Degradation of Materials. 3rd ed., William Andrew Publishing, 2018.

Society of Automotive Engineers. Automotive Lighting Technology and Human Factors in Driver Vision and Lighting. SAE International, 2019.

United States Department of Transportation. "Federal Motor Vehicle Safety Standards; Lamps, Reflective Devices, and Associated Equipment." National Highway Traffic Safety Administration, Federal Register Vol. 83, No. 195, 2018.