Pressure Washer Oil Change – The Why, When & How Guide

If you’re reading this, you have probably no clue about how to change the oil in your pressure washer. You might have heard someone say that pressure washers need oil changes on a regular basis to keep them operating smoothly. So you did a quick search and landed here, well don’t panic, you’re right where you need to be.

Here you will find all the information you need to keep your power washer running safely, efficiently, correctly and economically. Before we get too far into this, you need to consider what type of pressure washer you own. Is it powered by electricity? Or is it fuel-powered?

Fuel-Powered Or Electric-Powered Pressure Washer?

Why is this important? Because if you own a fairly cheap electric powered pressure washer, then you don’t have to perform an oil change. You see most budget electric powered pressure washers, need no maintenance at all.

They have what are called sealed units, this means you can’t get into them so there’s no need to change the oil. Even if you felt the need, it’s impossible as there is no way of draining the old oil and no way of replacing it with fresh oil either. Budget electric powered pressure washers are designed to last for as long as they last and then when they stop working, you just go out and replace them.

The more expensive models do have the capability of maintaining the water pump, and this will need regular oil changes. But unless you have an expensive electric-powered pressure washer or a fuel-powered pressure washer there’s no need for oil changes.

Why Change The Oil On A Pressure Washer?

pressure washer machine

Like most engines pressure washers rely on oil to keep all the moving parts from seizing up. As the engine runs, it heats up so without oil to keep the parts moving the metal parts which expand under heat would rub together and eventually break. Making sure the oil is clean and fresh will allow the oil to do its job unhindered.

Engine oil has a cleaning agent in it that removes any particles that could damage the moving parts of the engine. These particles are trapped in the oil filter and the oil flows back around the system. Over time the oil loses its viscosity, or how smoothly it performs.

To describe viscosity in simple terms, think of butter, when butter is cold, it is hard and won’t spread, when it’s warm it glides over bread with ease. So old oil becomes thicker and less able to lubricate the parts than fresh, new oil. This means engines running on old oil are more likely to develop problems than engines with regular oil changes. 

Why Change The Oil In A Pressure Washer Water Pump?

Without the water pump, a pressure washer or power washer is useless. The pump powers up the water flow leading to it having a stronger force to clean your driveways or whatever. As engine parts don’t operate as well with old oil, it’s the same with water pumps. 

When Should You Change The Oil In A Power Washer?

The correct answer for this can be found in your instruction manual that came with the power washer. But as a general rule, you should change the pump oil every 200 to 250 work hours, so every 3 months if you use it regularly or every year if not. Speaking of the instruction manual, that will also tell you the correct oil to use to replace the old oil in the pump.

Which Oil Is Best In A Power Washer Water Pump?

car oil

Oil’s oil right? Well sort of, yes, you see the oil is all oil but it’s the additives they put into the oil that makes the difference. Without getting too technical about it, engine oils have detergent additives to actively remove contaminants from the working parts of the engine. 

These contaminants get trapped in the oil filter so they can’t damage any working parts, and during regular servicing, the oil filter gets replaced. If you used engine oil in a power washer’s water pump it would gum up very fast and need replacing at more frequent intervals to prevent damage. That’s why pump oils don’t contain detergent additives.

Water pump oils contain anti-foaming agents and anti aeration additives instead, these anti aeration additives prevent the oil from losing its viscosity keeping the pumps moving parts safer for longer. The anti-foaming agents prevent a build-up of foam on top of the oil that could cause any seals to leak and lead to oil shortage and damage to the pump.

How Is Pump Oil Labelled?

Pump oil will not necessarily be called water pump oil, it will more than likely be called non-detergent oil or N D oil. If you can’t find this, you can use oil made for classic cars, as pre-1923 cars had no oil filters so the oil they use is perfect for power washer water pump oil replacement. The problem with classic car oil is they charge a premium for it, so try to get N D oil if possible.

How To Change The Oil In A Power Washer Water Pump


So now you’ve established that you own a fuel-powered power washer with a water pump that can be given an oil change, and the right period of time has passed indicating that the oil needs changing, how do you go about it? Firstly don’t get worried, you’re going to see lots of instructions and maybe you’ll be put off, well let me start by reassuring you, this is a simple job. Anyone can do it, that is anyone with the right equipment, you will need:

  • Pump oil – See above for the correct oil to use if in any doubt consult your instruction manual. If you don’t have a manual or you’ve lost it, consider telephoning the company that manufactured your model and asking them.
  • Pan – Or tray to catch the old pump oil, this prevents mess and environmental damage.
  • Funnel – When refilling the pump with oil, it’s safer and easier to use a funnel to prevent spillage.
  • Spanner – You will probably have a plastic knob to undo for drainage purposes but some models have proper bolts. If it does have a bolt you’ll need a spanner to remove it.
  • Container – Store used pump oil in a container with a secure lid, to keep it safe until it can be disposed of safely. Anything will do, old pop bottles are ideal as the screw lid keeps the oil safely in the bottle.

How To Give The Power Washer Pump An Oil Change

Best Pressure Washers

Now you have all the equipment to hand, you can get on with the oil change. Here’s our step by step guide on how to change the oil in a pressure washer water pump. It’s always best to do the oil change after you have just finished using the power washer as warmed up oil will flow easier than cold oil.`

  1. Place the pan or tray directly under the water pump drainage bolt. To catch the old oil.
  2. Remove the top bolt on the pressure washer water pump. This will remove the pressure and allow the oil to freely drain.
  3. Removed the bottom bolt to drain the oil out of the pump. You might get some on your hand as you remove the drainage bolt, consider wearing gloves for protection.
  4. Once all of the oil has stopped flowing, replace the drainage bolt in the bottom of the pump. Taking care to not overtighten.
  5. Place the funnel into the filler hole located at the top of the pump.
  6. Pour the correct oil into the funnel
  7. Fill to about the ¾ full mark and stop.
  8. Remove the funnel
  9. Replace the bolt into the filler hole and tighten (but not overtighten).
  10. Using the funnel, pour the old oil into your container (pop bottle) from the pan or tray collected when you drained the pump. Secure the lid.
  11. Turn the pressure washer back on and inspect for any oil leaks. If you notice a leak tighten the bolt slightly.

The Best Way To Dispose Of Used Water Pump Oil

The best option is to recycle the oil, of course, we can’t do that safely but many garages and stores have the facilities for recycling oils. Contact your local garage or mechanical supply store and see if they will take your old oil.

If not recycling centres run by local authorities will usually have a recycling facility for oil. Some might charge a nominal fee but it’s better than the exorbitant fine you’ll receive if you’re caught dumping old oil.

If you don’t have a recycling centre near you, check on the local council’s website for waste disposal centres and see if they will take it. They usually do and again some might charge a fee for this service but it’s a small price to pay to save the planet. Not to mention your wallet from an environmental pollution fine.

Frequently Asked Questions

What kind of oil do you use in a pressure washer pump?

Pressure washer pumps use non-detergent oils which can be purchased at most good garden centres. Or you can use classic car engine oil, but they charge much more for this.

How often should pressure washer pump oil be changed?

If you bought it brand new, you should give your pressure washer pump oil its first oil change after 10 hours of usage. From then on it’s recommended to change the oil every 200-250 work hours or once a year.

Can I use motor oil in my pressure washer pump?

Regular motor oil contains detergents to clean the moving parts of contaminants, these are removed by an oil filter. As pressure washer pumps don’t have filters using motor oil will damage the pump and cause it to break down.

What is SAE 30 oil?

SAE 30 oil is a motor oil with a viscosity rating of 30 as given by the Society of Automotive Engineers.

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