How to Remove Oil Stains from a Concrete Driveway

Concrete is porous. When motor oil, transmission fluid, or cooking grease hits a concrete driveway or garage floor, it soaks into the microscopic pores within minutes. The longer the stain sits, the deeper it penetrates. Fresh stains (less than 24 hours old) respond to simple treatments. Old stains may require multiple applications or more aggressive methods.

Fresh Stains: The Cat Litter Absorption Method

Pour a thick layer of unscented clay cat litter (the cheap, non-clumping kind) over the fresh oil stain immediately. The diatomaceous earth or bentonite clay in the litter absorbs oil like a sponge. Grind the litter into the stain by stepping on it and twisting your foot, which forces the absorbent material into the concrete pores where the oil is collecting.

Leave the litter on the stain for 12 to 24 hours. Sweep it up and dispose of it. For stains less than a few hours old, this single treatment removes 80% to 90% of the oil.

If you do not have cat litter, baking soda, cornstarch, or even sawdust work as substitute absorbents. Cat litter is the most effective because of its clay mineral composition, which has a molecular affinity for hydrocarbons.

Dish Soap and Hot Water (For Moderate Stains)

Squirt a generous amount of degreasing dish soap (Dawn is the standard recommendation because its surfactant formula was literally designed to cut petroleum-based grease) directly onto the stain. Add enough hot water to create a puddle. Scrub vigorously with a stiff-bristle brush (a deck brush or push broom works) for 2 to 3 minutes.

Let the soapy solution sit on the stain for 30 minutes, then scrub again and rinse with hot water from a garden hose. The surfactants in dish soap emulsify the oil (break it into tiny droplets suspended in water), allowing it to be rinsed away.

The Baking Soda and Vinegar Poultice (For Set-In Stains)

Mix baking soda with enough water to form a thick paste. Spread it over the stain in a layer about 1/4 inch thick. Pour white vinegar over the paste; it will fizz as the acid reacts with the baking soda. The effervescence helps lift oil from the concrete pores through agitation.

Cover with plastic wrap to keep the paste moist and let it work for 24 hours. Scrub and rinse. This method works on stains that are days to weeks old.

The TSP Solution (For Old, Deep Stains)

Trisodium phosphate (TSP), sold at hardware stores for about $5 per box, is a powerful alkaline cleaner that breaks down petroleum stains in concrete. Mix 1 cup of TSP with 1 gallon of hot water. Pour onto the stain, scrub with a stiff brush, and let it sit for 30 minutes before rinsing.

TSP is the most effective chemical solution short of commercial degreasers. Wear rubber gloves; TSP is alkaline enough to irritate skin. It is also an environmental concern in waterways (phosphates cause algal blooms), so use it sparingly and avoid letting rinse water flow into storm drains.

Pressure Washer (For Large Areas)

A pressure washer at 2,500 to 3,000 PSI with a 25-degree nozzle tip can blast oil residue out of concrete pores through pure mechanical force. Pre-treat the stain with dish soap, let it sit for 15 minutes, then pressure wash. The combination of chemical degreasing and mechanical force handles even years-old stains.

Rent a pressure washer from Home Depot for $40 to $60 per day if you do not own one.

Seal the Concrete After Cleaning

Once the stain is removed, apply a concrete sealer ($25 to $40 per gallon, covers about 200 square feet) to prevent future oil penetration. A sealed concrete surface allows oil spills to bead on the surface, where they can be wiped up easily before soaking in. Reapply sealer every 2 to 3 years.

Bottom Line

Fresh stains: cat litter for 24 hours, then dish soap scrub. Older stains: baking soda and vinegar poultice or TSP solution. Severe stains: pressure washer with degreaser pre-treatment. Seal the concrete afterward to prevent repeat staining.