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How to Change Pressure Washer Pump Oil: Complete Guide

Keep your pump in pristine condition when you change your oil. 

Not every pressure washer comes with a pump that needs regular oil changing, but many do.

If your pressure washer pump is due for an oil change, we’ll show you, step by step, how to change your pressure washer pump’s oil. This will keep your pressure washer well maintained, so it functions better and lasts longer.

Key Takeaways

  • Check the manufacturer’s guidance to see if your pressure washer pump needs oil changes.
  • To change the oil, run the pressure washer for a couple of minutes, drain the old oil, and add new non-detergent-based oil.
  • Most pressure washer pumps require 30w non-detergent oil, but always refer to the manufacturer’s recommendations.
  • Change the pressure washer pump oil roughly every three months or every 200-250 hours of work, depending on the manufacturer’s guidance.

Do You Need to Change Your Pressure Washer Pump Oil?

It depends on what type of pressure washer pump you have. Most basic pressure washers — those under $400 — don’t require pump maintenance. But you should always check your manufacturer’s guidance.

Another way you’ll know that you never need to change your pump’s oil is if you have a wobble or axial piston pump. These are usually filled with oil during manufacturing and permanently sealed, so even if you wanted to change the oil, you couldn’t.

However, other pumps do need their oil changed. You’ll know you need to change your oil yourself if the manual requires regular oil changing or if your pump has a drain and fill plug.

Keeping on top of oil changes has many benefits to your pressure washer, including:

  • Pumps need oil to reduce wear and tear, friction and heating of the moving parts. Oil can prevent these parts from failing prematurely.
  • As mentioned, it reduces overheating. This protects the seals as heat expands the seals and increases the risk of cracking.
  • If you don’t keep up to date with oil changes, you could void your warranty.

So if your pump requires manual oil changes, it’s best to adhere to this guidance.

How to Change Pressure Washer Pump Oil

Let’s get into the best method for changing your pressure washer pump oil.

What You Need

  • Something to catch the oil that exits. You can use an old tray or an actual oil pan.
  • A wrench to open the bolt access. Your pressure washer may have a plastic knob instead of a bolt.
  • A funnel to fill the pump with oil.
  • An oil storage container.
  • Oil as recommended by the manufacturer.
  • Rags for cleaning.
  • Optional: an oil drain plug, a suction gun, or manual/electric pump.

Step by Step Instructions

1. Purge the Pump

Turn on the supply water and remove the wand from the spray gun. Start the engine and hold the pressure washer gun trigger for two minutes to empty the residual water and dirt. This also heats up the pressure washer, which helps get rid of dirt more easily.

2. Drain the Oil

Now you need to drain the oil and fuel from the engine. Firstly, you will need to loosen and remove the reservoir top access bolt — or unscrew the knob — to relieve the pressure inside. If you have a bolt, this is where your wrench comes into play.

You have four options for removing the oil. One is draining it from the bottom of the oil pan using an oil drain plug. You can also suction it out with a suction gun. Or you can pump it out using an electric or manual pump.

You could also just tilt the pressure washer both ways to pour the used oil into your container.

If necessary for the other options, have an oil pan or old tray ready to catch the residual oil.

3. Store the Oil

Once you have poured out the old oil, pour it into your oil storage container and set that aside for now. You will need to dispose of this according to your local regulations. Now, put the drain bolt or knob back into place.

4. Add New Oil

Before using our method, make sure to check your manufacturer’s guidance, as this will vary depending on the pressure washer and pump that you have. Some models have premeasured bottles of pump oil.

In general, you should use a non-detergent pump oil. Grab your funnel and pour the oil into the pump until it’s about ¾ of the way full.

5. Close Up the Pump

Now put the bolt back and tighten it firmly. Use a rag to wipe up any spilled oil around the cap or surrounding area. Put your pressure washer into the upright position. After a couple of minutes, you’re ready to use your pressure washer again.

Top Tip

You will need to dispose of the dirty rags in accordance with your local regulations.

FAQs About Changing Pressure Washer Pump Oil

What Kind of Oil Do You Use in a Pressure Washer?

It depends on what your manufacturer states, but for the most part, you need a low oil without additives or detergents.

A modern engine uses detergent oil since the machine has an oil filter. The detergent cleans the engine while the oil filter keeps the soap out of the bearings. You shouldn’t use this kind of oil unless your manufacturer specifically calls for it.

However, for regular pumps, there is no oil filter, so you must use non-detergent oil. If you don’t, all the contaminants that the oil has cleaned off the surfaces will flow through the oil, which can wear down the inside of the pump.

What Is 30w Non-Detergent Oil?

This is a non-detergent motor oil that most pressure washer pumps use. It’s also used on other tools with small engines, such as lawn motors. It is ideal because most pressure washer pumps use splash lubrication, and this oil will prevent the foam that the dippers can cause.


Just because this is the most typical oil to use doesn’t mean you should go out and buy it. Always check your manufacturer’s guidance first.

Can I Use Motor Oil in My Pressure Washer Pump?

Yes, but check if this is suitable with your pump. Motor oil lubricates pumps, but many have additional additives, so you should know what to look for when shopping.

They may not be labeled as pump oil, but you want to make sure they will work. So double-check to make sure what you’re looking at is without detergent or says ‘ND’ (non-detergent) on it.

Some may also be labeled as being for classic cars or early 1920 model engines. This works because these cars didn’t have oil filters.

How Often Should Pressure Washer Pump Oil Be Changed?

Roughly every three months or so. In other terms, this is around every 200 to 250 hours of work. But before sticking to that advice, check the manufacturer’s regulations first, as it may change depending on your specific model.

How to Make Your Pump Oil Last Longer

There’s nothing you can do to make the oil last longer. Just make sure to put in the recommended amount and change it when recommended by the manufacturer. It may seem often to change it every 250 hours of work, but this will keep your pump in the best condition.

Why is My Pressure Washer Pump Oil Milky?

Your pressure washer pump oil is milky because water is leaking into the oil via the oil gasket. It reacts and turns it a white milky color.

What Does SAE Mean On Oil?

The SAE on motor oil means Society of Automotive Engineers and references the viscosity of the oil. The SAE are the group responsible for coding viscosity levels in motor oil.

Oil Overview

Now that you know how to change your pressure washer pump oil, you’re heading in the right direction of great pump maintenance. Pumps can be expensive, so nailing down this routine will help you extend the life of your pressure washer pump.

It only takes five short steps to change your oil, and once it’s done, you can get back to using your pressure washer. Just be sure to change the oil within the next 200-250 hours of work!

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About the Author

Beth McCallum

Beth McCallum is a freelance writer & book blogger with a degree in creative writing, journalism, and English literature. Beth firmly believes that a tidy house is a tidy mind. She is always looking for new ways to sustainably clean and tidy her house, that's kind on the environment but effective in the house, too!