Running clean oil in your pressure washer's pump is one of the best ways to ensure long life and efficient performance from your machine. The pump is the heart of your pressure washer and runs at high temperatures and RPMs, eventually breaking down the oil. The pump oil should be changed on a regular basis with quality pressure pump oil and kept at the recommended level.
Change the pump oil after the first 10 to 15 hours of operation. This ensures that any metal fragments from the manufacturing process are removed and fresh oil is substituted. During normal service, replace the oil every 200 to 250 work hours, about every three months if you use your machine often, and at least every year if not. One way to remember to change the oil in your pump is to schedule it along with changing the oil in the pressure washer's engine.
To change the pump oil, place a drain pan under the machine below the pump. Remove the pump oil filler cap and the pump oil drain plug. Allow the oil to drain completely from the pump. To catch the oil without making a mess, on some models you may have to use a funnel or piece of tubing to guide the used oil to the drain pan. Replace the drain plug and fill the pump with DP70 pump oil. Use only the quantity specified in your pressure washer's manual for your pump. If you're not sure, measure how much oil you drained and replace with that amount. Most pumps have an oil window or sight glass on the side of the pump, with a mark or red dot indicating the proper level for the oil.
Change your pump oil if it looks milky, changes color or has visible particles. Always use oil specifically designed for pressure washer pumps. Good pressure washer pump oil is non-detergent, non-foaming and has rust inhibitors. Never overfill the pump with oil, which could lead to leaks caused by damaged seals. Never pour used oil into a storm drain or sewer. Dispose of old oil properly by recycling or taking it to a used-oil collection center. Always follow manufacturer recommendations and instructions for types of oil, locations of oil filler caps and drain plugs and oil quantities.