What oil is used in a pressure washer pump?

Pressure washers are powerful cleaning tools that use pressurized water to remove dirt, grime, and debris from surfaces like driveways, houses, cars, and more. At the heart of a pressure washer is its pump, which pressurizes the water and pushes it through the hose and nozzle at high velocities. Pressure washer pumps require proper lubrication to function correctly and prevent excessive wear and tear. Choosing the right oil for your pressure washer pump is important for optimal performance and longevity.

What does the pump oil do in a pressure washer?

The oil in a pressure washer pump serves several key functions:

– Lubrication – The oil coats all the internal moving components in the pump, reducing friction and wear. Good lubrication prevents premature pump failure.

– Cooling – As the pump operates, it generates heat from the friction of moving parts. The oil helps dissipate this heat and prevent overheating.

– Sealing – The oil forms a seal between close-fitting metal surfaces in the pump, preventing water leakage and loss of pressure.

– Rust prevention – The oil coats the internal metal components, preventing corrosion and rust over time.

– Noise reduction – Proper lubrication reduces noise from the pump operation.

Using the manufacturer’s recommended oil ensures optimal lubrication and protection for your specific pressure washer pump model.

Types of pressure washer pump oil

There are a few main types of oil used in pressure washer pumps:

1. Standard/regular pump oil

This conventional mineral-based oil is formulated specifically for use in pressure washer pumps. It contains anti-wear additives like zinc phosphate to protect internal components. This affordable oil works for many residential pressure washers.

2. AW32 hydraulic oil

AW32 hydraulic oil has a viscosity grade of 32, meaning it flows well at warmer temperatures. It provides good lubrication for moving parts while resisting breakdown. This type of oil is common in commercial-grade pressure washers.

3. AW46 hydraulic oil

With a higher viscosity grade of 46, AW46 hydraulic oil is thicker than AW32. It offers extra protection for high-pressure, high-heat pump applications. This oil is used for heavy-duty pressure washers.

4. Synthetic oil

Synthetic oils like Mobil 1 can provide maximum protection for pumps. Synthetic oil flows well at low temperatures while resisting thickening at high temps. It keeps pumps extra well-lubricated. Synthetic oil is more expensive but lasts longer.

Can you use motor oil in a pressure washer pump?

It’s not advisable to use standard motor oils like 10W-30 in a pressure washer pump, even though it’s a metal component with moving parts similar to an engine. Here’s why:

– Detergent additives – Motor oil contains detergent additives tailored for engine deposits, not needed in a pump. These additives can cause excess foaming.

– Zinc levels – Motor oil contains very high levels of zinc compared to pump oil. Excess zinc can leave deposits in a pump.

– Viscosity – Motor oil is usually multi-grade, meaning its viscosity changes a lot with temperature. Pumps function best with oil of consistent viscosity.

– Oxidation – Motor oil is designed to handle blow-by gases and oxidation not present in a pump. The antioxidants added can degrade pump seals with extended use.

So it’s best to use oil designed specifically for pressure washers, like standard pump oil or hydraulic oils. This optimizes lubrication and prevents premature wear.

Recommended oil for popular pressure washer pump brands

Here are the oils typically recommended or specified by major pressure washer pump manufacturers:

AR pumps

– AR Blue Clean pumps – AR390 pump oil
– Other AR pumps – AW32 or AW46 hydraulic oil

Cat pumps

– Smaller Cat pumps (2200-4000 psi) – SAE 30W non-detergent oil or Cat pump oil
– Larger Cat pumps (4000+ psi) – AW32 or AW46 hydraulic oil

General/Briggs & Stratton pumps

– Standard pressure washers – SAE 30W non-detergent oil
– Commercial models – AW32 hydraulic oil

Simpson pumps

– Residential – SAE 30W non-detergent pump oil
– Commercial – AW32 hydraulic oil

Annovi Reverberi (AR) pumps

– AR Blue Clean pumps – AR390 pump oil
– Other AR pumps – AW32 or AW46 hydraulic oil

Comet pumps

– Smaller Comet pumps – SAE 30W non-detergent oil
– Triplex/larger pumps – AW32 or AW46 hydraulic oil

Always check your pressure washer manual for the exact oil recommendation. Using the manufacturer’s recommended oil will provide the best performance and longevity.

Pressure washer pump oil weight and viscosity

For most residential pressure washers, an oil weight/viscosity grade of SAE 30W is recommended. This 30-weight oil provides adequate viscosity to lubricate and seal pump components, while flowing well at typical outside temperatures.

Some key notes on 30W oil:

– The “30” refers to the viscosity grade at operating temperature. A lower number means thinner viscosity.

– The “W” means this is a multi-viscosity oil, able to flow well in cold winter temperatures.

– “Non-detergent” 30W oil is preferred, to avoid excess foaming and deposits.

For commercial pressure washers, AW32 or AW46 hydraulic oils are common. The AW designation means anti-wear protection. The higher viscosity grades provide extra protection for high-pressure pumps.

Too light of an oil can fail to properly lubricate and leak past seals. Too heavy of an oil may not flow properly. So use the recommended weight and type of oil for your pump.

How much oil does a pressure washer pump take?

The oil capacity for pressure washer pumps can vary greatly depending on the pump model and size:

– Small electric pumps – Around 8-16 oz (0.25-0.5 L)

– Medium homeowner pumps – 16-40 oz (0.5-1.2 L)

– Large vertical shaft pumps – Up to 80 oz (2.4 L)

– Commercial triplex plunger pumps – 100 oz (3 L) or more

Always consult your owner’s manual to find the stated oil capacity for your exact pump model. Measure carefully when filling to avoid under or overfilling the pump reservoir.

Insufficient oil will lead to inadequate lubrication, while too much oil can cause leakage or foaming issues. Use the recommended oil amount for optimal pressure washer performance.

How often to change pressure washer pump oil

Here are some general guidelines on how often to change the oil in your pressure washer pump:

– Small electric pumps – Every 50 hours or 6 months

– Larger pumps < 3000 psi - Every 100 hours or Yearly - High pressure pumps > 3000 psi – Every 50 hours or 6 months

– Heavy commercial use – Every 200 hours or semi-annually

But the best practice is to follow the oil change frequency recommended in your pressure washer’s manual for your specific model. Oil change intervals can vary based on:

– Pump pressure rating and workload
– Oil sump size and capacity
– Oil type and quality

Change the oil more frequently if it appears contaminated or degraded. Be sure to regularly check the oil level and top it off when needed. Proper oil changes prevent damage and maximize pump life.

Step-by-step guide to changing pressure washer pump oil

Here are the basic steps to safely change the oil in your pressure washer pump:

1. Run the pressure washer to warm up the oil so it drains better

2. Disconnect the spark plug wire

3. Clean the area around the oil fill plug/cap

4. Place a drain pan underneath the pump

5. Remove the oil fill plug/cap

6. Allow the old oil to fully drain from the pump reservoir

7. Inspect the drained oil for metal particles or excessive contamination

8. Obtain the correct amount of new pump oil for your model

9. Carefully pour the fresh oil into the pump reservoir

10. Replace the oil fill plug/cap once full

11. Reconnect the spark plug wire

12. Dispose of old oil properly at a recycling center

13. Clean up any spilled oil

14. Run the pump and check for leaks

15. Dispose of drain pan and supplies

Refer to your owner’s manual for any specific instructions on accessing the pump oil reservoirs, filters, venting, etc. Proper oil changes keep your pressure washer pump running smoothly.

Signs it’s time to change your pressure washer pump oil

Here are some signs that indicate it’s time to drain and replace the old oil in your pressure washer pump:

– Oil appears dark black or milky

– Sludge is visible in the oil

– The oil smells burnt or fuel-contaminated

– Metal particles or pieces detected in the oil

– Oil level is low and consumption has increased

– Pump is overheating or leaking oil

– Unusual noises like squeaking coming from the pump

– Pressure output seems lower than normal

– Has reached the recommended hours of use per oil change interval

Don’t continue running your pressure washer if you notice these red flags. Drain the old oil and refill with fresh oil to optimize pump operation and longevity.

Disposing of pressure washer pump oil properly

Proper disposal of used pump oil is important for safety and environmental reasons:

– Allow oil to fully cool before handling

– Pour oil into leak-proof containers; don’t use food/drink bottles

– Take the sealed containers to your local recycling center

– Ask if they accept used oil; many do at no charge

– Place oil in designated collection tanks; don’t dump down drains/sewers!

– Check for any hazardous waste days in your area

– Some auto parts stores accept used oil drop-offs

– Consider having oil changed professionally to avoid disposal

Proper disposal prevents pollution and protects the environment. Check local regulations about used oil recycling and disposal methods.

Can you use other fluids in a pressure washer pump besides oil?

It’s not recommended to use other fluids like diesel, kerosene, transmission fluid, or water in place of proper pressure washer pump oil:

– Lack of lubricating qualities – Only oil provides the needed lubrication

– Contamination – Chemical residues can contaminate the pump

– Seal degradation – Non-oil fluids can degrade pump seals and gaskets

– Part damage – Inadequate lubrication promotes wear, scoring, galling

– Water encouragement – Moisture ingress leads to pump rust/corrosion

– Fire hazard – Flammable liquids like gasoline impose safety risks

– Environmental impact – Improper disposal of hazardous fluids

Save yourself pump repairs and only use manufacturer-recommended pressure washer oils. They’re specially formulated to protect and extend the life of your pump.

Pressure washer pump oil recommendations

Here are some good oil recommendations for pressure washer pumps:

Standard pump oils

– Cat Pump Oil
– Generac Pump Oil
– Briggs & Stratton Pump Oil
– Craftsman Pump Oil
– PowerCare Non-Detergent 30 Weight Oil

Hydraulic oils

– Mobil DTE 24 Hydraulic Oil (ISO 32)
– Shell Tellus S2 MX 32
– Castrol AW 32 Hydraulic Oil

Synthetic oils (if recommended)

– Mobil 1 15W-50
– Royal Purple 15W-40
– Amsoil Signature Series 25W-50

Again, be sure to use the specific oil weight, type, and formulation recommended by your pressure washer manufacturer. This will maximize pump protection and performance.

Storing oil-filled pressure washers over the winter

For pressure washers filled with oil that will sit idle over the winter months, here are some storage tips:

– Add fuel stabilizer to prevent fuel deterioration

– Drain water from all hoses, coils, and connections

– Use pump saver or RV antifreeze in the pump if needed

– Store indoors or cover unit well if outdoors

– Place on blocks to avoid sitting on cold ground

– Disconnect and remove battery if equipped

– Drain excess oil if overfilled for winter use

– Clean exterior surfaces and apply rust inhibitor

– Place muffler side down to avoid water entry

Proper winter storage protects your pump oil and prevents problems starting up next season. Be sure to prep your pressure washer following the manufacturer’s recommendations.

Conclusion

Choosing the right oil specifically designed for pressure washer pumps is critical to proper lubrication, cooling, rust prevention, and sealing. Most residential pumps use standard SAE 30W non-detergent oil, while commercial models often take AW32 or AW46 hydraulic oil. Always consult your owner’s manual and use the oil weight and type recommended by the manufacturer. Properly maintaining the oil and changing it at regular intervals will maximize your pressure washer pump’s performance and working life. Following the recommendations and best practices outlined will keep your pump primed and pressure washing like new.