Ray Magliozzi
Dear Car Talk:
Is there a magic bullet for cleaning oil spills off concrete?
My house sitter’s car leaked something oily in the garage and driveway, and kitty litter, cement powder, baking soda, dish soap, and Krud Kutter ain’t cutting it.
Thanks!
— Emmy
The magic bullet is to sell the house on a rainy day, Emmy.
Oil stains are hard to get out and easiest to get out when they’re still fresh. Once they’ve really penetrated into concrete, they’re much harder to clean.
The fact that there are a bazillion “concrete cleaner” products on the market lets you know that there are a lot of people out there trying one thing after another, hoping to find one that actually works.
If you can catch the stain when it’s fresh, some of the things you tried might do it — kitty litter, a paste made of laundry detergent, scrubbing with Dawn soap. But, once the oil has seeped in there, you need something to penetrate the concrete and dissolve the stain or pull it out.
If you look online at your favorite monolithic shopping conglomerate’s website, you’ll find a long list of products that claim to clean concrete. But I’d start by trying one of the enzymatic cleaners.
They use little microbes that actually eat the oil. They’ve been used in industrial spills for years and work pretty well on many stains.
There’s one called ACT Concrete Cleaner. It’s a powder that you shake over the stain. Then you take a push broom and work it in a bit, and make sure the stain is fully covered. Then, you walk away and give the microbes some privacy while they eat.
You check on the stain a couple of weeks later and see how it looks. Most likely, if your stain is deep and has been sitting there for a while, you’ll have to re-treat it several times. And it may never disappear completely.
You can also try one of the non-enzymatic cleaners. There’s one called Zep Purple Cleaner, which has been around for eons and is also used by industry.
You can mix it in different concentrations, depending on how bad the stain is. That’s worth a try, too.
And after that, it’s sort of guesswork for me with the multitude of products out there. In the future, offer your house sitter a personalized cardboard box to park over.
Got a question about cars? Write to Ray in care of King Features, 628 Virginia Drive, Orlando, FL 32803, or email by visiting the Car Talk website at www.cartalk.com.
