Does Dawn Dish Soap Work To Clean Asphalt?

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If you were around in the early 1970s when Dawn dish soap first came out, you might remember the advertising slogan, "Dawn takes grease out of your way." Touted for its ability to break grease up and surround it so it's easier to wash away, Dawn has even famously been used to clean wildlife caught in oil spills. If you have a fresh oil stain on your asphalt driveway and you're looking for the right cleaner, Dawn will work, but there are better products to consider for long-term stains.

Normally, oil refuses to mix with water, but with soap molecules, one portion is attracted to oil, and the other is attracted to water. When an oil molecule is completely trapped by soap, it creates a micelle that can be washed away. That's how Dawn dish soap "breaks up" oil and grease particles, and it works on asphalt, too, but there's a problem that soap can't fix. 

Since the binder in asphalt is made from petroleum, motor oil stains aren't just cosmetic. If stains and drips are left too long, the oil breaks down the asphalt binder and causes visible damage that no cleaner can fix. There are a lot of unexpected things you can clean with dish soap, but with asphalt, you have to get to it in time. Your window for cleaning it up is when you first notice a dark spot. If it's left too long, it can even get soft enough to press your thumbnail into.

To clean up oil stains in your driveway, start with pouring cat litter on the stain to absorb as much of it as possible. Leave it overnight to make it easier to clean the bulk of the mess. The next day, after removing the cat litter, pour Dawn right onto the stain and scrub it with a stiff brush. Let it sit about 20 to 40 minutes so the soap can work, then rinse. This method works best on cool asphalt in mild weather, but keep in mind that asphalt gets soft and is easier to damage in the summertime. Asphalt is porous, so you might have to repeat this process if you notice later that there is still oil coming up to the surface.

If the stain is too stubborn for Dawn, you can try some other affordable kitchen staples to remove oil stains from asphalt driveways. Baking soda is another option for absorbing oil, and you may already have Simple Green All Purpose Cleaner Concentrate on hand. If not, it's available from Amazon for $6.98 at the time of writing. After testing a spot, which you should always do when you're cleaning asphalt, pre-wet the area before pretreating it with full-strength Simple Green. Wait 10 minutes before scrubbing with a diluted solution, then allow it to work a bit longer before the final rinse.