How to remove oil stains from concrete driveways and garage floors

Step by step: how to remove oil stains from concrete driveways and garage floors

Safety first. Work outdoors or with the garage door open. If you use a solvent poultice (acetone or similar), wear chemical-resistant gloves and eye protection and keep it away from flames, pilot lights and cigarettes; solvent fumes are flammable. Never wash oil, degreaser or solvent into a storm drain, and keep kids and pets off the area until it is rinsed and dry.

1. 1

   Blot up wet oil without spreading it

   Press paper towels or rags onto the puddle to lift as much liquid oil as you can. Blot, do not wipe: wiping smears the oil over a larger area and pushes it into the pores of the concrete.

2. 2

   Cover the spot with absorbent

   Pour a layer of clay cat litter about 1/2 inch thick over the stain and a little past its edges. Grind it in with the sole of your shoe or a brick so it breaks down and makes contact with the oil.

3. 3

   Leave it for several hours or overnight

   Let the absorbent sit at least a few hours, ideally overnight, to draw oil up out of the surface. On a fresh spill you will see the litter darken as it soaks the oil up.

4. 4

   Sweep up and dispose of it properly

   Sweep the oily litter into a heavy trash bag. Check your local rules: many areas treat oil-soaked absorbent as household hazardous waste rather than regular trash. Repeat the litter step if the litter came up very dark.

5. 5

   Scrub with hot water and detergent

   Wet the stain with hot water, sprinkle on powdered laundry detergent or squeeze on dish soap, and scrub hard with a stiff nylon brush for 2 to 3 minutes. Let it sit about 15 minutes so the surfactants can loosen the oil.

6. 6

   Rinse and contain the runoff

   Rinse with a small amount of water and soak up the dirty water with fresh litter or rags rather than hosing it toward the street. Let the spot dry fully; damp concrete always looks darker, so judge the result only when it is dry.

7. 7

   Treat what is left with a stronger method

   If a shadow remains, use a concrete degreaser or an enzyme cleaner as its label directs, or a poultice for a small, stubborn spot (see below). Old stains often need two or three rounds.

Which oil stain method works best on concrete?

Fresh drips come out with an absorbent and detergent; stains that have soaked in for months need a degreaser, enzymes or a poultice. Pick based on how old and how deep the stain is.

Concrete Network’s guide to embedded oil explains that degreasers act like ball bearings to loosen oil without breaking it down, which is why they struggle on heavily contaminated, long-standing stains, and why microbial cleaners that digest the oil are often the better choice there.

How to make a poultice for a stubborn oil stain

A poultice is an absorbent soaked in solvent, left on the stain so the solvent dissolves the oil and the absorbent pulls it out as it dries. It suits small spots, not a whole driveway.

• Mix an absorbent (clay cat litter, sawdust or diatomaceous earth) with enough acetone to make a thick paste, outdoors and away from any flame.
• Spread it about 1/4 inch thick over the stain, slightly past the edges.
• Cover it with plastic sheeting and tape the edges down so the solvent does not evaporate too fast.
• After about 24 hours, remove the plastic, let the paste dry completely, then scrape and sweep it up. Repeat if the stain has lightened but not gone.

Test on a hidden spot first if the concrete is sealed, stained or painted, since solvents can soften coatings. Do not use solvents on asphalt, which they can damage.

What not to use on oil stains

Skip the internet tricks. Concrete Network warns that cola, WD-40, bleach and vinegar can leave discoloration on concrete without removing the oil. Strong acids are no better: they etch the surface.

• Do not use muriatic acid on oil stains; it attacks the concrete, not the oil.
• Do not mix bleach with other cleaners, and keep it out of this job entirely.
• Do not pressure wash oil toward the street. A hot-water pressure washer with degreaser works well, but the runoff must be contained and collected.

How to dispose of the oil and stop new stains

Collect it and take it to a recycling or hazardous waste drop-off, never down a drain. The EPA’s used oil guidance says to store used motor oil in a clean container with a tight lid, not mixed with anything else, and take it to a service station, oil change shop or recycling center. The EPA’s household hazardous waste page covers how to find local collection for oily rags and absorbent.

To prevent new stains, fix the leak, keep a drip pan or piece of cardboard under the car until you do, and consider sealing a garage floor so oil sits on top instead of soaking in. Our guide to cleaning concrete floors covers the rest of the garage.

Mistakes to avoid

• Wiping or hosing a fresh spill, which spreads the oil and drives it deeper.
• Using bleach, vinegar or soda on the stain, which can discolor concrete without lifting the oil.
• Washing oily water or degreaser into the storm drain.
• Judging the result while the concrete is still wet and dark.
• Using a solvent poultice near a water heater pilot light or other flame in the garage.