How to Get Oil Stains Out of Concrete (Shops, Docks & Lots)

To get oil out of concrete, pull up anything still liquid with an absorbent, then work a heavy-duty degreaser into the stain, keep it wet long enough to penetrate, agitate it with a stiff brush or floor machine, and rinse with hot water under pressure. A fresh spill usually lifts in one cycle. A stain that has soaked in for months takes two or three cycles, and on porous, unsealed concrete a faint shadow can remain even when the surface is clean.

This guide is the method maintenance crews use on shop floors, loading docks, fleet yards, parking areas and warehouse aisles: what to do in the first hour, how to attack old stains, which pressure and nozzle to use, and how to keep oily wash water out of the storm drain. The same method is how to clean grease off concrete behind restaurants and at drive-thrus.

What Removes Oil Stains From Concrete Fastest?

A degreaser, enough dwell time and hot water under pressure remove oil from concrete fastest. Each one handles a different part of the job: the degreaser breaks the bond between the oil and the concrete, dwell time lets it reach down into the pores, and hot water plus pressure flushes the loosened oil out.

Concrete is porous, so oil does not sit on top of it. It wicks down into the capillaries of the slab. That is why a quick hose-down spreads a fresh spill without removing it, and why an old stain looks gone while the slab is wet and comes back as it dries. Match the method to the age of the stain:

Stain	Method	Equipment
Fresh spill (minutes to hours)	Absorb, degrease, agitate, rinse	Absorbent, stiff nylon brush, pressure washer or wet vacuum
Days to weeks old	Heavy-duty degreaser, wet dwell, agitate, hot rinse	Hot-water pressure washer with a surface cleaner
Months or years old	Repeat the heavy-duty cycle two or three times	Hot-water pressure washer, low-speed floor machine with a scrub brush
Indoor floor with no drain	Pre-treat, agitate, recover the dirty solution	Walk-behind floor scrubber

How Do You Clean Up a Fresh Oil Spill on Concrete?

Contain the spill and soak it up before you add any water. Water on a fresh spill just floats the oil across more concrete and pushes it toward the nearest drain.

1. Block the spread. Ring the spill with absorbent and cover any floor drain or storm inlet nearby.
2. Absorb the free oil. Spread granular absorbent or pads over the spill, work granules in with a broom, give them time to soak, then sweep up and dispose of the oily absorbent under your site's waste rules.
3. Degrease the residue. Spray JANITORI Degreaser No.71 directly on the mark, let it work for 30 to 60 seconds, and scrub with a stiff nylon brush.
4. Rinse and recover. Rinse with hot or cold water and pick the rinse water up with a wet vacuum or floor scrubber instead of washing it toward a drain.

On a working floor, speed is not optional. OSHA's walking-working surfaces standard requires floors to be kept free of hazards such as leaks and spills (29 CFR 1910.22), and NIOSH lists slips, trips and falls as the second most common cause of lost-workday injuries in general industry (NIOSH 2013-100).

How Do You Get Old, Set-In Oil Stains Out of Concrete?

Treat an old stain as a repeated cycle, not a single wash: heavy-duty degreaser, a wet dwell, mechanical agitation and a hot rinse. Two or three cycles on the same stain are normal, and each one pulls more oil out of the pores.

1. Sweep the area dry. Grit left on the slab turns into slurry and shields the stain from the degreaser.
2. Mix at heavy-duty strength. JANITORI Degreaser MAX No.72 runs at 20 mL per 4 L of water for normal soil; the label allows 40 mL per 4 L (about 1.3 fl oz per gallon) for extreme buildup, which is what an old stain is.
3. Apply generously. Cover the stain plus a few inches of margin with a pump sprayer so it goes down at full working strength. A pressure washer's chemical injector dilutes whatever it draws a second time, so it is the wrong tool for this step.
4. Keep it wet while it dwells. Give it several minutes and re-mist if the edges start to dry. Degreaser that dries on the slab stops working.
5. Agitate. Use a deck brush on spots. On a whole bay or loading dock, a low-speed rotary floor machine with a scrub brush, such as the Mercury Hercules 20" floor machine at 175 RPM, works the degreaser into the whole area evenly.
6. Rinse hot. Rinse with a hot-water pressure washer, ideally through a surface cleaner, working from the high side of the slab toward your recovery point.
7. Let it dry and inspect. Oil shadows only show honestly on dry concrete. Repeat steps 2 to 6 on whatever remains.

On a stain that has been soaking in for years, expect a big improvement rather than a brand-new slab. Oil that has wicked deep into unsealed concrete can leave a faint shadow after the surface itself is clean.

Does Hot Water Really Make a Difference on Oil?

Yes. Heat thins oil and speeds up the degreaser, so hot water removes oil in fewer passes than cold water at the same pressure. Cold water with a good degreaser handles fresh spills; recurring grease on shop floors, fleet yards and drive-thrus is hot-water work.

That is why hot-water machines dominate truck shops and equipment yards. The Pressure-Pro Hot Shot 4012-10C delivers 4,000 PSI at 4.0 GPM from a Honda GX390 engine and a CAT pump. If you already own a good cold-water machine, the Pressure-Pro Hot Box HBS12V40 is a 12V diesel water heater built to add heat to an existing 4.0 GPM, 4,000 PSI pressure washer.

Compare every model in our commercial pressure washer range.

What PSI and Nozzle Should You Use on Concrete?

For oil on concrete, 3,000 to 4,000 PSI through a 15° or 25° tip, or better, a rotary surface cleaner, is the working range. Flow matters as much as pressure: more gallons per minute rinse the loosened oil off the slab faster.

• Skip the 0° red tip. A pinpoint stream is concentrated enough to etch concrete and leave permanent lines.
• Keep the wand moving. Hold a 15° or 25° tip roughly 8 to 12 inches off the surface and sweep in overlapping passes.
• Use a surface cleaner on anything bigger than a parking space. Spinning nozzles under a hood give an even, stripe-free finish. The Dapper Supply 20" surface cleaner is listed at 2,500 PSI and its maker recommends a machine of 2,500 PSI or higher, such as the high-flow Pressure-Pro Eagle II EB5525HG (2,500 PSI, 5.5 GPM, belt drive).

Tip colors, angles and orifice sizes are all in our pressure washer nozzle chart, and the chemistry side is covered in pressure washer soap vs degreaser.

Can You Remove Oil From an Indoor Concrete Floor Without a Drain?

Yes. Indoors, a floor scrubber replaces the hose: it scrubs and vacuums the dirty solution back into its recovery tank in one pass, so nothing runs across the floor or into a drain.

Pre-treat the stained area with No.72 and let it dwell, then run a walk-behind scrubber such as the Dapper Supply self-propelled 20" scrubber (14.5 gal tank) over it. Put only low-foam chemistry in a scrubber's solution tank, watch the recovery tank on the first run, and stop if foam builds, because foam pulled into the vacuum motor damages it. For daily upkeep of the same floor, see how to clean a concrete floor.

Where Should the Oily Wash Water Go?

Not into a storm drain. The EPA's stormwater guidance on vehicle maintenance and washing points out that storm drains lead directly to local waterways, not to treatment facilities, and calls vehicle maintenance facilities stormwater hot spots (EPA stormwater BMP).

• Block and collect. Cover storm inlets and recover rinse water with a wet vacuum, scrubber or water-recovery setup.
• Choose the chemistry on purpose. The same EPA sheet recommends biodegradable, phosphate-free, water-based detergents and limiting how much you use. No.72 and No.71 are plant-derived, biodegradable and contain no phosphates, petroleum solvents or VOCs, and dosing to the label keeps the amount down.
• Check your permit and your city. Where oily wash water can be discharged depends on your site's stormwater permit and local sewer rules under the EPA NPDES stormwater program.

How Do You Keep Oil Stains From Coming Back?

Catch the drips and clean on a schedule. Most chronic stains come from the same parking spots, forklift bays and equipment pads, so fix those spots first.

• Put drip pans or absorbent mats under parked equipment and known leakers.
• Keep absorbent and a spray bottle of No.71 at every bay so fresh drips are handled within the shift.
• Seal bare concrete after a deep clean. A sealed slab absorbs far less oil, so the next spill wipes up instead of soaking in.
• Scrub high-traffic concrete weekly so traffic film never builds into a stain.

Frequently Asked Questions

Will pressure washing alone remove oil stains from concrete?

Rarely. Water alone does not dissolve oil, so pressure washing without a degreaser moves surface oil around and leaves the stain in the pores. Apply a degreaser first, let it dwell, then pressure wash, preferably with hot water.

How long should degreaser sit on a concrete oil stain?

Several minutes, and it must stay wet the whole time. Re-mist the area if the edges start to dry, then agitate before rinsing. Old stains usually need two or three full cycles.

Will degreaser damage concrete?

JANITORI Degreaser MAX No.72 and Degreaser No.71 are both labeled for use on concrete. As with any cleaner, test on an inconspicuous area first, especially on sealed, stained or decorative concrete, and rinse thoroughly after use.

Can you remove a years-old oil stain completely?

Often you can remove most of it, but not always all of it. Oil that has wicked deep into unsealed concrete can leave a faint shadow even after repeated hot-water cycles. Sealing the slab afterward keeps the next spill on the surface.

What PSI do you need to clean oil off concrete?

Around 3,000 to 4,000 PSI with a 15° or 25° tip, or a surface cleaner matched to your machine's pressure rating. Higher flow in gallons per minute rinses faster, and hot water matters more than extra pressure.

Related Guides

• How to Clean a Concrete Floor: Commercial Methods That Work
• Pressure Washer Soap vs Degreaser: What to Use and How to Apply It
• Pressure Washer Nozzle Chart: Colors, Angles and Tip Sizes

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