How to Deep Clean Oil Stains from a Concrete Garage Floor

Oil stains are the inevitable signature of a well-used garage, but they don't have to be permanent fixtures. Over time, these spots sink deep into the porous surface of your concrete, inviting dust and grime to bond with the residue, which turns a small spill into a dark, unsightly blemish. Restoring your floor requires more than a standard sweep. You are looking to break down the chemical structure of the oil and lift it out of the pores entirely. When done correctly, the concrete returns to its natural, lighter hue, creating a workspace that is safe, clean, and free of slippery hazards.

  1. Clear the workspace first. Move all vehicles, tool chests, and storage bins out of the garage to ensure total access to the slab. Sweep the entire floor thoroughly to remove loose debris, dust, and spiderwebs that would otherwise turn into sludge during the cleaning process.
  2. Soak up wet oil first. If any oil is still wet or tacky, cover the area generously with kitty litter or sawdust. Let the material sit for at least two hours to pull the excess liquid out of the floor before sweeping it away.
  3. Test before committing. Apply a professional-grade concrete degreaser directly to the stained areas. Follow the manufacturer's concentration ratio, but keep the mixture thick enough that it coats the stain without immediately running off.
  4. Work the chemical deep. Use a stiff-bristle nylon brush to work the degreaser deep into the pores of the concrete. Scrub in circular motions to agitate the oil, continuing until the cleaner begins to foam or change color as it lifts the oil.
  5. Let chemistry do the work. Let the degreaser sit on the surface for 15 to 20 minutes, but do not let it dry out. If the floor begins to look patchy or dry, lightly mist it with water to keep the chemical reaction active.
  6. Flush away all residue. Use a pressure washer set to a wide fan tip to spray away the degreaser and lifted oil. Work from the back of the garage toward the door, pushing the dirty water out onto the driveway or into the floor drain.