Onan RV recommends changing the oil every 100 hours or once a year, whichever comes first. It only takes about 20 minutes and you will be good to go for the season. You will need a T30 torx bit, a 12mm socket, an oil pan, a funnel and 1.6 quarts of SAE30 or 15W-40 oil. The Cummins Onan RV Generator Handbook can be viewed or downloaded below.
First, warm up the generator for 5 minutes. Once warm, under the generator, remove the oil drain plug protection plate using a T30 Torx bit. You can then remove the oil drain plug using a 12mm socket.
Allow the oil to drain into a safe container. Install oil drain plug but do not install protector plate at this time.
Fill generator with 1.6 quarts of Onan approved oil and start engine. Check oil drain plug to ensure no leaking. If there is no leaking, turn off engine and replace oil drain plug protector.
Check the oil level using the dip stick at the oil fill location. Wipe any oil from generator and properly dispose of the used oil. It is a good time to also check the generators air filter. Remember to read owners manual as your generator may be different and require additional steps.
Watch how to change the oil in an Onan RV QC 4000
Watch how to exercise and maintain the carburetor in an Onan RV QC 400
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