How do I clean oil off a garage floor?

Concrete is porous, so oil soaks in rather than sitting on top. That means absorbing what has not yet penetrated, and drawing out what has. The longer a stain has been there, the less completely it will come out.

What you'll need

• Cat litter or sawdust
• Stiff brush
• Degreaser or washing powder
• Hot water
• Gloves

Step by step

1. For fresh oil, cover it thickly with cat litter or sawdust immediately.It absorbs what has not yet soaked in. Leave several hours, or overnight.
2. Sweep up the absorbent and dispose of it as household waste.Do not wash it into a drain — oil should not enter the water system.
3. Make a paste of biological washing powder and hot water, or use a concrete degreaser.Biological powder contains enzymes that break down oil and is cheap.
4. Work the paste in with a stiff brush and leave it to dwell for 30 minutes.Keep it damp — if it dries out it stops working.
5. Scrub again, then rinse with hot water.Hot water carries far more oil away than cold.
6. Repeat for stubborn stains rather than scrubbing harder.Two or three moderate treatments beat one aggressive one on porous concrete.
7. Once clean and dry, consider sealing the floor.A concrete sealer stops future spills penetrating and makes them wipe up instead.

Tips

• A drip tray under a car or mower prevents the problem entirely and costs very little.
• Very old oil stains are essentially permanent — a sealer or floor paint over the top is often the practical answer.
• Never use petrol or solvents to clean a garage floor. The fire risk in an enclosed space is serious and unnecessary.

Common mistakes

• Washing oil into a drain — It contaminates watercourses and, in many places, is an offence.
• Using solvents indoors — Fumes accumulate in an enclosed garage and are both a health and fire risk.
• Scrubbing dry stains without a dwell time — The cleaner needs time to penetrate porous concrete. Force does not substitute.

Questions people ask