Can I Use Synthetic Oil in My Pressure Washer?

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Electric pressure washers need oil to run their system, and gas models need it for the pump and engine. Filling, replacing and changing it is something we always do with pressure washers, often without second thought. But what happens if you use synthetic oil? Will it make things better or worse in terms of performance?

Most gas and electric pressure washers use non-detergent oil for the pump. However there are some gas pressure washers that can use synthetic motor oil in their engine. Check the manufacturer recommendations before proceeding.

Because oil plays such a critical role in pressure washers, it is important that you learn what type to use. In this guide you will learn what kind of oil works best for pressure washer pumps and engines, how often to replace the oil and how to do it.

Is it Safe to Use Synthetic Oil in Pressure Washers?

The general rule is that pressure washer pumps should only use non-detergent oil. This applies to both gas and electric models like the BILT HARD Gas Pressure Washer 3100 PSI. The engines of most gas pressure washers however, will run on synthetic oil and performance may improve.

Take note of the word “most”. Some pressure washers may not like synthetic oil in their engine, while others do. You should check the owner’s manual if you are not sure.

Detergent oil works with gas engines because they have a filter that prevents dirt from getting in. Essentially what the filter does is trap the grime and dirt so they cannot affect the engine.

Image Credit: Steened

What is certain is that pressure washer pumps must only use non-detergent oil. Otherwise the pump may not run or get damaged. Because pumps do not have filters, dirt will build up more quickly and affect performance.

Since pumps do not have filters there is no way to prevent dirt from getting into the oil. A dirty pump is going to make it difficult if not impossible for water to flow. The more you use a pressure washer the faster it gets dirty, so a detergent oil is impractical for washer pumps.

Synthetic vs. Regular Oil – a Comparison

How long pressure washers last depends on the type of oil you use. So it is important that you do this properly. To make things simpler we will explain the difference between synthetic and regular oil.

To recap, synthetic oil may be used on pressure washer engines, but pressure washer pumps only work with non-detergent oil. Synthetic oil has superior viscosity, safeguards engine parts better and has greater efficiency. Engines that use synthetic oil are less prone to oxidization which is good for these machines.

If the pressure washer lets you choose between regular and synthetic engine oil, synthetic is the better option. The following are three major reasons why it is the right option.

No deposits. Regular oil forms deposits which are harmful to the engine. These are natural products of petroleum oil and cannot be avoided. Over time these impurities make pressure washers less efficient.

Synthetic oil does not generate deposits like these so it is better for the engine. If you are going to gravity feed your pressure washer for instance, its engine must be clean and robust.

Less viscous. Regular oil viscosity is affected by temperature. The oil gets thin when temperature goes up and gets thicker when temperature drops. If the weather is variable in your area, this can be a problem as viscosity affects oil reliability.

Synthetic oil is not vulnerable to temperature changes, so its consistency level remains the same. This is a huge advantage if you use a pressure washer in hot and cold weather. This also means you have to worry less about the oil turning gummy during the cold.

Better lubrication. The harder an engine runs, the faster its parts wear out. Synthetic oil does a better job of lubricating the engine compared to regular petroleum. Lubrication is the key to making a pressure washer engine last even with high psi and GPM levels.

How to Change the Engine Oil in a Pressure Washer

So you have finally decided to use synthetic oil for your pressure washer. Question is, how often do you change the oil and how to do it? Some pressure washers like the Simpson Cleaning PS60843 PowerShot have a low oil shutdown feature. This tells you right away oil is required.

Pressure washer oil can be changed every 100 hours. But it all depends on how often the washer is used. You should consult your owner’s manual and follow their suggestions for oil change frequency.

To replace the oil, follow these steps.

Step 1. If the pressure washer engine is off, turn it on. Let it run a while as warm oil is easier to work with. Turn the engine off after the oil warms up.

Step 2. Look for the engine drain plug and place a container underneath it.

Step 3. Remove the drain plug screw. Take the oil filler cap off too.

Step 4. Drain the oil. By letting the engine warm up earlier, the oil will flow out much faster.

Step 5. When the oil is completely drained, reconnect the drain plug

Step 6. Pour synthetic oil in the engine. Check for oil leaks.

Some manufacturers suggest that you replace the oil after 24 hours, and after that change every 100 hours. But that is only a general guideline and you should refer to the instructions for your specific model.

How to Change Pressure Washer Pump Oil

Pressure washer pump oil is changed every year at the minimum. A heavily used pressure washer might need pump oil change every 3-6 months or every 300 hours use, whichever comes first.

To replace the oil, look for the filler cap and drain plug. Take them off and drain the oil in a bucket or pan. Plug the drain plug into place and put the new oil in. Remember, use only non –detergent oil.

When changing the pump or engine oil, you must have the right materials on hand. You need the new oil, a bucket to drain the old oil into, and a screwdriver or wrench to remove the drain plug. It is also a good idea to have a piece of rag or cloth to wipe any oil spillage.

If you changed the oil, try running the washer right away. It is important that you find out if there are any problems with it. The pump is crucial to the pressure washer, so you have to know right away if there are issues.

Tips for Using Synthetic Oil in a Pressure Washer

Changing oil in pressure washer engines is easy enough. But there are things you need to do to make the process even more efficient.

Be patient. Sometimes it can take a while for oil to drain, especially if it is cold. The oil thickens and takes longer to come out. For this reason it is best to do this during summer or after letting the engine run. If the oil is old – you have not changed it in a while- the draining process can really take a while.

Inspect the oil quality. Wondering if you are changing the oil frequently enough? Look at the oil as it comes out. If it has a whitish consistency or particles, you have to change oil more often.

Note to electric pressure washer users: electric motors do not use synthetic oil. Its pump uses non-detergent oil so make sure to use whatever product the manufacturer recommends.

What Type of Synthetic Oil Should I Use?

Use whatever product the pressure washer manufacturer suggests. If there is none, look for those made by well-known companies like Briggs and Stratton, Generac and Cat. These companies offer many types of oils for pressure washers so you should be able to find one that matches your make and model.

By browsing through the various products available, you can easily tell if the oil is for a pump, engine, electric, gas model and so on. The more research you do, the easier it will be to find the appropriate one for your pressure washer.