How to Remove Oil Stains from Garage Concrete

Concrete acts like a hard, grey sponge for motor oil, quickly soaking the dark liquid deep into its porous surface. Once the oil penetrates, simply wiping the top layer away does nothing to address the trapped residue that continues to seep upward. To successfully restore the look of your garage floor, you must pull the oil out of the pores rather than just washing the surface. Done well, this process eliminates the oily shadow that remains after a spill. You need patience and a bit of mechanical scrubbing to break the bond between the oil and the concrete. Avoid using wire brushes on finished or sealed concrete floors, as these can leave permanent scratches behind.

1. Soak Up the Spill First. If the oil is fresh and still liquid, cover the spill with clay-based cat litter or sawdust. Let it sit for at least four hours to soak up as much surface oil as possible before sweeping it away.
2. Paste On the Degreaser. Generously coat the stained area with a heavy-duty powdered laundry detergent or a concentrated commercial concrete degreaser. Add just enough water to the powder to create a thick, spreadable paste.
3. Work It In Deep. Using a stiff-bristled nylon scrub brush, work the paste into the concrete using circular motions. Apply firm downward pressure to ensure the bristles drive the soap into the pores of the floor.
4. Let Chemistry Do Work. Let the paste sit on the stain for at least 30 minutes, or longer if the stain is aged. Do not let the paste dry completely, as it needs moisture to hold the lifted oil in suspension.
5. Flush and Squeegee Away. Flush the area thoroughly with hot water from a hose or a bucket. Use a squeegee to push the dirty water toward the garage door or a floor drain to prevent it from resettling elsewhere.
6. Retreat Stubborn Shadows. Examine the concrete once it is dry. If a shadow remains, repeat the application of the degreaser paste, as deep stains often require multiple treatments to fully draw out the oil.