Well, that’s weird! I scratched my head and stared at my 25-year-old car’s headlights. I’d attempted the viral online life hack where you wipe foggy headlights with bug spray to make them clear again. It had worked beautifully—for a while. But just a month later, my headlights were even more opaque than before.

Cleaning your headlights with bug spray

Longtime readers know I bought a 1999 BMW Z3 convertible last year and have been writing updates on everything that breaks and everything I modify. It’s a sort of rolling platform for various automotive DIY maintenance experiments. So when I saw the viral online “clear up your headlights with bug spray” life hack, I grabbed some Off! and a rag.

The long and short of it is that spraying bug spray on a rag or paper towel, then wiping cloudy headlights, does a great job clearing them up. All the viral TikTok videos don’t exaggerate. But there are some major downsides to this method.

First: Why does this work? The DEET in the bug spray is a strong enough chemical that it actually dissolves a thin layer of the headlight’s plastic lens. That’s the layer with all the micro-scratches that make the lens appear cloudy. So, with the scratches gone, voilà, the headlight looks a lot clearer.

What do professional kits from 3M and Sylvania do? They use grit to essentially sand down and repolish headlights. So, the exact same thing as DEET? Kind of.

The downsides to DEET

One downside to DEET is that it can dissolve so much of the lens that it damages the headlights. That’s why experts warn against spraying it directly onto the lens.

A second downside of DEET is that after you’ve wiped down your headlight with bug spray, you’re usually left with a sticky residue of dissolved plastic and bug spray coating the lens. Even soap and water won’t remove this film. And as I found out the hard way, that sticky residue attracts grime and dust and can rapidly make your headlights dimmer than when you started.

Luckily for us, Matthew at Cincinnati Automotive found a way to clear that sticky film away. In a YouTube video (embedded below), he found that after you wipe a headlight with bug spray, you can wash it off with white vinegar. The vinegar is acidic enough to remove the bug spray goo, but not acidic enough to further dissolve the lens. It’s a win-win. And I even found it removed some of the bugs stuck to my bumper.

I’ve tried this new protocol: bug spray and then white vinegar. I have to say, my lenses are even clearer than with bug spray alone—they look nearly new. But we’ll have to see how it holds up. That’s because the professional headlight polish kits have a third element, a sealant to protect the newly cleaned plastic, and that’s the step there’s no hack for.

In my next BMW Z3 update, I’ll write up how my headlight hack is holding out. But in the meantime, if your headlights are cloudy, it might be worth splurging on the professional polish kits that you can get on Amazon for $10 or less.

Next, check out Cincinnati Automotive’s white vinegar hack in the video embedded below: