How do you remove an oil stain from concrete or asphalt?
Concrete is porous: the longer an oil stain stays, the deeper it goes. Acting fast makes all the difference. Here is the method for fresh stains and for old ones.
Updated
Quick answer
To remove an oil stain from concrete, first soak up the fresh oil with clay litter or an absorbent, then apply a concrete degreaser, scrub with a stiff brush, let it work and rinse with hot water, ideally under pressure. An old stain often needs several applications and may leave a faint mark.
Time: 30 minutes to 2 hours depending on the age of the stain
What you need
- Absorbent: clay litter, industrial absorbent or sawdust
- Concrete degreaser (alkaline or enzymatic), preferably biodegradable
- Stiff-bristle brush (no wire brush on decorative concrete)
- Hot water, or a hot-water pressure washer for large areas
- Gloves and safety glasses
Steps
- 1
Absorb the fresh oil
Cover the stain with absorbent, crush it in with your foot, leave it for a few hours, then sweep it up and dispose of it according to your municipality’s rules.
- 2
Apply the degreaser
Lightly wet the concrete, then apply the degreaser, undiluted or diluted according to the manufacturer, on the stain and a little around it.
- 3
Scrub
Brush vigorously in circles to work the product into the pores.
- 4
Let it work
Leave it for the recommended time without letting it dry; add a little water if needed.
- 5
Rinse
Rinse with hot water, ideally with a pressure washer. Collect the rinse water rather than sending it to the storm drain.
- 6
Repeat for old stains
A stain that is several months old often needs two or three applications, or a degreasing poultice left on for several hours.
What about asphalt?
Do not use a solvent (gasoline, thinner, solvent-based degreaser) on asphalt: it dissolves the bitumen and creates a hole. Use an absorbent, then a mild detergent and water.
Mistakes to avoid
- Hosing down a fresh stain first: water spreads the oil and pushes it into the concrete.
- Using bleach: it does not dissolve oil.
- Rinsing the oil toward the catch basins: it is prohibited in most municipalities.
When should you call a professional?
For an entire parking lot, an underground garage or many old stains, professional cleaning with a degreaser and pressurized hot water is more effective. HygiePro cleans commercial parking lots across Greater Montreal and manages the wash water.
Frequently asked questions
Does white vinegar damage concrete?
Yes, over time: its acidity attacks the surface of the concrete. And it does not remove oil. Use a concrete degreaser instead.
How do you clean oil that has dried?
An old stain has soaked into the concrete: apply a degreaser, scrub, let it work longer and repeat two or three times. A degreasing poultice left on for several hours helps “draw out” the oil.
How do you remove motor oil from asphalt?
Soak up the oil with clay litter, then wash with a mild detergent and water. Never use a solvent on asphalt: it dissolves the bitumen.