Changing the oil in a Waverunner is a relatively simple process, and it should be done about once every 100 hours of use. You’ll need a few basic items: an oil extractor (from your local marina), an oil rag, and your Waverunner user’s manual. The first step is to locate your oil filter using your user’s manual. Next, with the oil extractor, pump out about 2.5 quarts of oil. Next remove the old filter. Take your new filter and lube the O-ring with fresh oil, then tighten it down. Next add your standard Waverunner oil; Yamaha 2W oil for example. Make sure you don’t put too much oil in your Waverunner, or you can cause serious damage.
Once you’ve refilled the tank, hook up the water and run the Waverunner for about a minute. Check the dipstick when you’re done and make sure the tank is filled only to about the halfway mark.