Will Pressure Washer Remove Oil from Asphalt?

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We use pressure washers for heavy duty cleaning, and it does the job. But can a pressure washer remove oil from asphalt? Oil stains are unsightly and can be dangerous, so how do you clean it off?

A pressure washer can get rid of oil stains on asphalt. Use a 15 or 25 degree nozzle at 2500-3000 PSI. For hard to remove stains, 4000 PSI and 8 GPM might be required.

How to Pressure Wash Oil from Asphalt Safely

It takes more than just pressure washing to get rid of the oil though. You will also need other tools and materials which I will provide here.

What You’ll Need

Pressure washer
Oil degreaser (Chomp Stain Remover is a the best here)
Detergent soap
Bucket of water
Asphalt brush like the Maxman wire brush
Safety goggles
Gloves
Drop cloth
Rags

Your pressure washer must 2500-3000 PSI and up. I suggest the Simpson PowerShot 4400 or if you prefer electric, the Power Ryte 4000.

1. Prepare the area

Remove outdoor furniture, plants, children’s or pet toys, garden tools etc. in the area. Cover objects with drop cloth if you cannot relocate them far enough.

Sweep debris from the asphalt or use a leaf blower. The surface is going to get very slippery with oil stains and water so you have to remove all the debris for your safety.

2. Wear safety gear

Pressure washers are powerful and can cause injury. Wear goggles so water does not hit your eyes.

Wear gloves for your hands. It should be thick enough to protect your skin but still allow you to get a firm hold of the wand.

Wear pants, shoes and a long sleeve shirt. Basically you should cover your skin. Why? Because the force from a pressure washer can cut through skin.

It is also a good idea to wear protective gear since you’ll be working with degreasers and other substances.

3. Prepare the Degreaser

There are a lot of degreasers, but you should only use one that is specifically for asphalt oil removal. That stuff you use in the kitchen is not going to be enough.

Prepare the degreaser according to the product instructions. Apply the cleaner on the soil stains. If the oil stains are fresh, use a rag when you apply the solution. If the stains are old, spray it. Repeat for all oil stains on the asphalt.

Leave the degreaser on the asphalt for 5-10 minutes. This gives the degreaser time to absorb the oil.

4. Scrub

Scrub or brush the stains covered with degreaser. This is optional but I highly recommend it especially for old oil stains.

Brushing agitates oil and makes it easier for the degreaser to remove it. You can scrub by hand or use a broom brush attachment.

Whichever you prefer, make certain it is a heavy duty brush for asphalt. Ordinary brushes won’t be able to stir the oil. Look for hard bristles that won’t give way when scrubbed hard.

5. Apply soap

There are two ways to do this: apply soap by hand on the stains or pour the soapy water mix into your pressure washer tank.

I prefer using the pressure washer to apply soap as it’s easier and faster. This only works if you use a pressure washer certified soap detergent.

If you’re applying the soap by hand, any type of detergent will do. But if you’re going to use a pressure washer, the soap must be formulated for it.

Ordinary detergents contain ingredients that may not be suitable for pressure washers. The wrong product could cause damage so it’s best to be careful. Once the soap has been applied, leave it there for 5-10 minutes.

6. Pressure wash the asphalt

Make sure the pressure washer is turned off. Hold the trigger down so any remaining water comes out. Do this for half a minute.

Turn the pressure washer on. Plug a 25 degree nozzle on the wand. Aside from asphalt, you can use this nozzle to pressure wash decks. Set the PSI to 2500-3000.

Point the wand at the surface and spray. Move back and forth and overlap your strokes.

You can try a 15 degree nozzle if the stains are hard to remove. Be careful because this tip produces a lot of pressure and can remove concrete paint. Use only if the 25 degree tip doesn’t work.

Never use the 0 (red) degree tip because it can rip through the asphalt. I would suggest increasing up to 4000 PSI for really hard to remove stains.

Should You Use Gas or Electric Pressure Washers?

You can use a gas or electric pressure washer to remove asphalt oil stains. Both have their pros and cons.

Gas pressure washers are more powerful than electric, capable of 4000 PSI and up. If you have old stains on the driveway, gas models are worth considering.

Gas pressure washers are heavier though and can be hard to move around. Electric models are lighter but are tied to a cord. A gas model while heavy, won’t get bogged down by wires and cables.

Personally I prefer gas pressure washers because of the extra power. I also like the fact it doesn’t require an electrical outlet and I can haul it anywhere on the property grounds.

But if the oil stains are limited to one area or you have an extension cord, an electric pressure washer is going to work just fine.

The important thing is this: gas or electric, your pressure washer must be at least 2500-3000 PSI.

Can a Pressure Washer Damage Asphalt?

A pressure washer can damage concrete or asphalt if too much force is used. You can prevent this by keeping three things in mind: the nozzle, the PSI and the distance between the spray tip and asphalt.

Nozzle

The most common pressure washer nozzles are:

Black (65 degrees)
White (40 degrees)
Green (25 degrees)
Yellow (15 degrees)
Red (0 degrees)

You only need to use the green or yellow nozzles to pressure wash asphalt. Use green first and if that doesn’t work, try yellow. Avoid red because it is too powerful.

PSI

The higher the PSI the greater the water pressure. You have to balance the need for force without damaging the surface.

In most cases you should start at 2500 PSI. Anything below is probably not enough to remove the stain.

2500 PSI is fine for fresh oil stains, but old ones need more pressure to remove. From my experience it takes at least 3000 PSI to get rid of stubborn oil marks.

Distance

Keep the spray tip 6-12 inches from the asphalt. Start at 12 inches and move it closer if needed. The closest should be 6 inches.

If you are already at 6 inches and the stain won’t come off, increase the PSI. Asphalt is more durable than wood and other surfaces, but it cannot handle the red nozzle. Stick with green and if needed, the yellow tip.

If this is your first time to pressure wash asphalt, the key is to maintain the distance. When you find the right distance for the nozzle, keep it there.

How Long Does it Take to Remove Oil from Asphalt?

Pressure washing asphalt driveways usually take an hour or so. But getting rid of the stains depend on several factors.

Fresh stains are easier to remove. Apply the cleaner, wait 5-10 minutes and rinse. Even if there are several stained areas, the whole process won’t take too long.

Old oil stains are harder to get rid of. The longer the stains have been on the surface, the more effort it’s going to take. You’ll need heavy duty cleaners and it might take multiple applications.

It is not the pressure washing that’s going to take a lot of time. It is the stain removal, the scrubbing, brushing, etc. that takes a while.

The best to shorten cleaning time is to remove oil stains as soon as possible. If oil settles on the surface it’s going to require more time to remove it.