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Why Does a Pressure Washer Pump Need Oil?

A pressure washer pump needs oil because its inner parts are moving at higher speeds and oil ensures no friction or heat is created. When the inner parts of a pressure washer are not properly lubricated, the machine starts overheating and metal parts start expanding, which increases friction that can cause damage to parts and shortens the pump’s service life. A pressure washer pump oil is needed because not lubricating the pressure washer pump can also nullify the manufacturer’s warranty.

Which Type of Pressure Washer Pumps Needs Oil Changes?

Triplex pumps need oil changes while lower-rated and residential pressure washer pumps such as axial cam and wobble plate pumps don’t need oil changes.

1. Axial Cam and Wobble Plate Pumps

Pressure washers with PSI ratings lower than 2,500 or the ones that use water flow weaker than 2 GPM use factory sealed axial cam or wobble plate pumps that don’t need oil changes. Axial cam and wobble plate pumps are more prone to failure than triplex pumps but are affordable and can be easily replaced when they stop working.

2. Triplex Pumps

Both gas pressure washers and electric pressure washers come with built-in triplex pumps popular for their power and durability. Triplex pumps use three pistons to pump out water at consistently high pressure and have a unique and durable construction. Triplex pumps are hard to replace because of their design, which is why they need pressure washer pump oil to reduce friction and prevent overheating.

Pressure Washer Pump Oil Buying Guide

Pressure Washer Pump Oil Buying GuideWhen buying pressure washer pump oils, factors such as manufacturer recommendation, non-detergent oil, viscosity, and additives should be considered, all of which are listed below.

1. Manufacturer Recommendation

Pressure washer manufacturers typically make recommendations on the right type of pressure washer pump oil to use in user manuals. Some pressure washer manufacturers sell specifically formulated pressure washer pump oils for different types of pumps. If not using a pressure washer pump oil recommended by the manufacturer, that could cause harm to the pressure washer pump.

2. Non-Detergent Oil

The main difference between pressure washer pump oil and engine oil is that the latter contain detergents. Detergents pick up contaminants as they flow through the engine and bring contaminants to the oil filter, keeping the engine clean. However, pressure washer pumps don’t have oil filters, and using pressure washer pump oils with them would make the contaminant flow through the pump and wear it off.

Only non-detergent pressure washer pump oils should be used with pressure washer pumps. Non-detergent pressure washer pump oils contain anti-foaming and anti-aerating additives that prevent the formation of bubbles inside the pressure washer pump that can create cavities and damage the pressure washer pump long-term.

3. Viscosity

Pressure washer pump oils are all labeled with codes that represent the product’s viscosity or thickness of the liquid. The SAE designation tells the pressure washer pump oil viscosity or describes how easily it will flow through the pump. Most pressure washer pumps use SAE 10W-30 or SAE 10W-40 oil.

If the pressure washer pump oil or all-purpose engine oil is labeled with SAE 10W-30, the product’s viscosity is 10 in cold environments while its viscosity goes to 30 in warm temperatures, meaning the oil gets thinner.

4. Additives

Some pressure washer pump oils contain additives such as anti-foaming and anti-aeration additives that control the amount of air in the pump as well as anti-rust additives that prevent corrosion.

How to Change Pressure Washer Pump Oil?

To change pressure washer pump oil, the pressure washer should be flushed and disconnected from the water supply, then the top access bolt should be relieved, the oil should be flown out so the reservoir is empty, and new oil should be poured whilst making sure the reservoir is not overfilled, and the bolt should be taken back into place.

1. When to Change Pressure Washer Pump Oil

How to Change Pressure Washer Pump OilThe first time pressure washer pump oil should be changed is after the pressure washer has been working for 50 hours. The second time and every next time pressure washer pump oil should be changed is after every 100 hours of work or after the pressure washer has been working for 3 months.

Most triplex pumps come with a sight glass – a circle with a dot that shows how much oil should be poured into the reservoir. When the oil level of the pressure washer pump is under the dot, old oil should be drained and a new one should be added. Pressure washer pump oil should also be changed when its color turns milky.

2. What You Need to Change Pump Oil

  • Oil catch – a tray or bowl to drain the oil in
  • Wrench – to loosen up the bolt access, unless the pump has a plastic access knob
  • Funnel – to avoid spilling when pouring oil
  • Appropriate pressure washer pump oil

3. Steps to Changing Pump Oil

  • The pressure washer should be connected to the water supply, turned on, and all the water should be flushed out after 2 minutes, then the machine should be disconnected from the water supply.
  • The pump assembly should be removed altogether with the motor and set up on a workstation.
  • A drain bolt and a top access bolt should be detected. The top access bolt should be removed to relieve the air pressure.
  • The oil catcher should be placed under the pressure washer’s pump drain access, then the drain access should be opened so the oil flows out.
  • The drain bolt should be placed back into its position.
  • Pump oil should be poured through the top access using a funnel.
  • The oil reservoir shouldn’t be overfilled. Approximately 12 ounces of pressure washer pump oil should be poured into the reservoir.
  • The top access bolt should be tightened and the assembly should be mounted back.

FAQ About Pressure Washer Oils

1. How should I dispose of used pressure washer pump oil?

Pressure washer pump oil should be drained out of the pump, poured into an empty bottle, and brought to a recycling center or a car mechanic shop. According to EPA, recycling used oil can produce 2.5 quarts of lubricating oil per one gallon while the same amount of recycled oil can be produced by recycling 42 gallons of crude oil.

2. What is the difference between synthetic and natural oil?

Synthetic oil is of greater quality and purity than natural oil, performs better, lasts longer, and doesn’t get dirty as fast. Synthetical oil is also more expensive than natural oil. If following a regular oil change schedule, natural oil can be used instead of synthetic oil.

3. What to do if pressure washer pump oil is leaking?

When pressure washer pump oil is leaking, it is a sign that either the oil should be replaced or the pump itself should be replaced or repaired. You can check our blog on fixing pressure washer pumps for further details.

About Adam Wallace

Adam Wallace is passionate about speed – he loves his motorcycle and adores his car. He knows that if you want your vehicle to love you, you gotta love it back – so he spends a considerable time pampering his rides. Nothing beats the sparkle of paint after a good pressure washing, so he decided to share his best tips and tricks here.

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