Explained: The best oil for your pressure washer

Changing the oil on an engine is an important part of extending the life of your pressure washer. Many don’t realize that a pressure washer will have two oil tanks, one in the motor, and one in the pump. each will need a different type of oil.

The best oil to use for your pressure washer pump is a non-detergent pump oil. The pump has no oil filter, and will be susceptible to rust and other damage by other oils. The motor needs a general engine oil to run optimally.

Choosing the correct oil for you requires more specific information, as regional factors can impact the oil you need. It’s also important to know how often you need to change your oil, and how to do that when the time comes.

Oil for pressure washer pumps

The pump of a pressure washer is crucial to the function of the machine. Pumps, however, do not possess oil filters. On any general engine, oil has a detergent additive, which removes any general undesirable particles from the engine as the oil lubricates it.

The function of an oil filter is to catch the particles, debris, and other gunk that is picked up as the oil moves through the engine. This provides a rough cleaning on the oil, so whatever it picked up doesn’t get caught up in the engine, jamming it up and causing damage.

Without a oil filter, the pump on your pressure washer is completely exposed to the buildup of contaminates, and the oil will dirty far more quickly than it otherwise would, if you use an oil with an added detergent.

So, what makes a non-detergent oil better than the alternative? It doesn’t have any chemical additives to pick up contaminates, and instead sticks those contaminates to the interior walls of the pump, keeping them from being carried around to damage the rest of the pump.

The question then, of course, becomes, which oil is the best for an oil pump. The best rated and most recommended pump oil is this, Briggs & Stratton 6033 Synthetic Oil. It is rated to stay viscous at pretty much any temperature you will ever see, so your engine should run smoothly throughout the whole year.

It may also be worth considering looking into added features like anti-foaming or anti-aeration. While it isn’t generally a major issue with pressure washers, foam in the oil has the potential of building up pressure that could cause leakage.

Aeration, or bubbles of air trapped within the oil, similarly, doesn’t always come up as a problem, but can make your pressure washer noisy, and can cause the oil to lubricate less effectively. Many pump oils have additives to keep these issues from coming up, and your pump should indicate whether or not these are necessary.

Oil for pressure washer motors

Unlike its neighboring counterpart, the motor of you pressure washer will have an oil filter on it, making the whole detergent, vs non-detergent question meaningless.

However, as you will still have to change the oil in the motor, it’s important to consider what oil to use. While you could plausibly just use the same non-detergent oil in the motor that you use in the pump, there is a reason the modern engines have moved to the use of oils with detergent. They work better, and ultimately don’t goop up the entire engine like non-detergent oils do.

Because of this, I recommend using a separate oil for the motor than you do for the pump. The choice in oil for the motor is less specifically significant than the choice in oil for the pump. A general motor oil will due. Specifically, you should choose an oil that is rated for the climate that you live in.

Engine oils are rated by viscosity, so you will need to pick an oil that will have a low viscosity when you run your pressure washer. If you live in a temperate area, something rated at SAE 40, or, low viscosity at 40 degrees, is probably sufficient for your needs.

Where I live, the temperature varies widely based on the time of year. It’s freezing cold in the winter and hotter than I’d prefer in the summer, so I need something more like this 10W-30 oil, the first number being the winter rating, and the second being the summer rating.

While it can seem like a pain to have to purchase two different kinds of oil, in the long run it will be worth it. It isn’t so inconvenient that it’s worth the risk of damaging, or even having to replace your pressure washer.

Do you really need to change your oil?

Some of you, no doubt, will reach this section and think, “That’s ridiculous, or course you need to change the oil in your pressure washer.” You might think that a pressure washer has an engine, just like your car, so changing the oil is clearly necessary.

Most people use their car every single day. Most cars have an onboard computer that will tell them if it needs maintenance, and if not that, they will have a sticker on the inside of the windshield reminding you when to change the oil.

Your pressure washer will have none of these things, so it’s easy to see how someone might not realize that their pressure washer is in desperate need of an oil change.

You know that image of black oil that movies associate with cars? That is what the oil in your pressure washer will actually start to look like if you don’t change the oil in your car

What happens if you don’t change the oil in your pressure washer? The same thing that happens if you don’t change the oil in your car. At first the oil will just get dirty, then it will stop lubricating the engine as well as it needs to, then the engine will start to be damaged by the lack of lubrication, and eventually you might have to replace the whole thing.

Replacing your pressure washer could cost you anywhere from a few hundred, to several thousand dollars, and replacing the pump alone can still cost several hundred dollars. Do you need to change the oil in your pressure washer? The answer is a resounding yes! It will work out for the better in the long run.

When to change your oil

Now we come to the harder question. We just went over how your car has all of these features to help you know when to change the oil, and how your pressure washer has absolutely none of them. So how do you know when to change the oil? The answer is a bit tricky and not at all straight forward.

The answer really depends on how much you use your pressure washer. If you use it often, it is a good idea to change the oil in the pump once every three months. Barring that, you should consider changing the oil in the pump after every 10 hours of operation time. This is a general recommendation, the owners manual for your pressure washer may have more specific recommendations.

You may be a less consistent pressure washer user, or you may be unsure of just how many hours you have used your pressure washer. If you fall into this category, a general rule of thumb is to change the oil in your pressure washer once every year, if you don’t use it more than the recommendation.

Another note, you do not have to change the oil in the motor every time you change it in the pump. It is usually sufficient to change the motor oil only once a year, even if you use your pressure washer a lot, and have to change the pump oil often.

How to change your oil

Now that you understand the importance of changing the oil in your pressure washer, know the kinds of oil the different parts of it needs, and know how often to change your oil, you’re ready to learn exactly how to do it.

To change the oil on you pressure washer pump, all you need to do is locate the pump, place some sort of catch underneath the drain, and open it. Wait for it to drain out, put the cap back on, and fill it to the appropriate level. You should have a view window to test the depth, or a dipstick to serve the same function.

After refilling the oil tank, it is a good idea to ensure the oil level is right by running the engine for a moment. Shut it off, and test the oil level again. Adjust however you need to.

This video clearly demonstrates the process on a Honda engine, which may not match your model exactly, but should give you an idea of how to change the oil in your pressure washer pump.

The process for changing the oil in the motor of your pressure washer is very similar to the process for changing it in the pump. Start by locating the drain for the oil tank. Place a catch for the oil, remove the cap for the drain, and wait for the oil to stop draining out.

Replace the cap and fill the tank to the designated appropriate depth. Test with the motor’s dipstick to be sure it isn’t under or overfilled, and seal off the tank. With that you should be ready to go. I’ve linked another video, with the same Honda engine, so you can get a visual for the process.

Best of luck with all your future oil changes, and remember, if you run into any trouble, there’s no shame in going to a professional for help.

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