Concrete is porous, so an oil stain is not on the surface; it is in the top few millimetres. That is why wiping makes it worse, why water alone does nothing, and why the sequence starts with absorption rather than chemistry.
Absorb, then lift with alkalinity
Oil soaks into concrete, so absorb what is still liquid, then lift the rest with an alkaline degreaser at label dilution and dwell time. Scrubbing in circles spreads the stain; work from the edge inwards, rinse, and repeat rather than using a stronger mix. For old stains, a hot-water pressure wash finishes the job.
Prices are Freshway catalogue prices as at 16 September 2026 and are subject to change. Confirm the current price, and whether GST applies, before quoting.
Step one: absorb
For fresh oil, cover the stain with an absorbent — kitty litter, sawdust, or a commercial absorbent — and leave it for several hours, pressing it in with a boot. For older stains, the same trick works after you have re-wetted the surface with a solvent or degreaser, because the absorbent pulls the oil back out while it is mobile.
Do not hose the stain down at this stage. Water drives the oil deeper and spreads the edges, which is how a 200 mm stain becomes a 600 mm one.
Step two: alkaline degreaser with dwell time
- Wet the concrete around the stain so the cleaner does not dry out and the oil does not wick outwards.
- Apply the degreaser at label dilution, from the outside of the stain inwards.
- Leave it for 10–20 minutes. Agitate with a stiff brush or a rotary scrubber.
- Rinse and inspect. Repeat rather than increasing the concentration; over-strength degreaser leaves a residue that attracts dust.
| Product | Use | Price |
|---|---|---|
| Heavy Duty Degreaser 395 | Alkaline degreaser for concrete, driveways and workshop floors | A$60.00 |
| Quick Break Solvent Degreaser 426 | Solvent degreaser for heavy oil and carbon | A$74.00 |
| Agar HF Detergent | Heavy-duty detergent degreaser, 5 L | A$39.00 |
| Whiteley Tile Plus | Concentrated degreaser for hard surfaces | A$62.31 |
Step three: pressure washing
For a driveway or a workshop slab, pressure washing finishes the job: the degreaser loosens the oil and the water carries it away. What matters is the nozzle and the surface tool rather than raw pressure. A surface cleaner covers the slab evenly and stops the stripes a wand leaves, and a rotary tool gets into the texture of an exposed-aggregate finish.
Will the stain become permanent?
On a sealed concrete surface, most oil lifts. On unsealed, porous concrete that has been soaking for months, a shadow usually remains: the oil has penetrated past the depth any cleaner reaches. At that point the options are a poultice treatment over several days, or accepting the shadow and sealing the slab so it does not spread.
Two household answers are worth putting to rest. WD-40 is a light oil itself, so it re-wets the stain and leaves another one behind. Cola is acidic and contains sugar; it does nothing useful to a hydrocarbon stain.
Sealing the slab afterwards
Once the oil is out, sealing is what stops the next spill becoming the same job again. A penetrating or film-forming sealer slows absorption and makes cleaning easier, and on a workshop floor or a driveway it is the difference between a five-minute wipe and a half-day treatment.
Sealers need a clean, dry surface and a curing window, so the sequence is: clean, dry thoroughly for at least 48 hours in good weather, apply the sealer evenly, and keep traffic off it for the period on the label. On a slab that is also used for food handling or vehicle maintenance, check whether the surface needs a slip rating before you seal it.
Questions we get asked most
- How do you remove dried oil stains from concrete?
- Re-wet the stain with a solvent or degreaser, cover it with an absorbent and press it in, then clean with an alkaline degreaser and rinse. Dried stains usually take two or three cycles rather than one strong application.
- Will WD-40 remove oil stains from concrete?
- No, and it makes the problem worse: it is an oil-based product, so it adds to the stain and leaves a fresh one. Use it only as a light solvent on a small spot, and remove the residue.
- Will an oil stain become permanent on concrete?
- On unsealed concrete, a faint shadow often remains after months of soaking, even after proper cleaning. Sealing the slab afterwards stops the stain spreading and makes the next spill easier to remove.
- Does Coca-Cola remove oil stains from concrete?
- No. It is an acidic sugar solution and it does not dissolve hydrocarbon oil. It also leaves a sticky residue that attracts dust to the stain.
- What pressure should I use on concrete?
- Enough to lift the soil without etching the surface. On most slabs that means a 15° or 25° nozzle with a surface cleaner, rather than a zero-degree jet held close to the concrete.
References
- NSW Environment Protection Authority — chemicals and wash water.
- SafeWork NSW — chemicals and other substances.
Workshop or car park full of oil?
Send a photo and tell us whether the concrete is sealed or raw, and we will recommend the chemistry and the machine for the area. Browse degreasers or ask our team.