How to Change the Oil and Filter on a Four-Stroke Jet Ski (PWC)

Park the PWC on its trailer on level ground, chock the trailer wheels, and use the jack to level it if needed. Remove the seat (and engine cover if fitted). Leave it open a few minutes so any fuel vapors can clear, then look around the engine for oil, coolant or fuel leaks before you start.

The engine sits right under the seat. This older two-stroke shown has no oil dipstick; four-stroke engines add a dipstick tube and an oil filter cover on top or to the side.

Warm oil flows out more easily and carries more dirt with it. Connect the garden hose to the flush fitting and warm the engine following your manual's flushing steps. Most makers want the engine started before turning on the water and the water turned off before stopping the engine, so water can't back up into the engine. Stay within the run-time limit, and let it cool between runs if the manual says so.

Some engines hold oil in other parts of the engine that won't reach the dipstick tube unless you do a short rev and shut-off. Sea-Doo, for example, has owners give a brief rev and stop the engine at that RPM before extracting, so oil returns to the tank. Only do this if your manual says to, and only with the flush water connected.

Remove the dipstick and the oil fill cap. Mark the extractor hose at the depth your manual specifies with tape, push it down the dipstick tube to the mark, and pump the oil into the extractor or a pan. Keep pumping until only air comes up.

Sea-Doo's procedure adds crank-and-extract cycles: reinstall the cap and dipstick, reattach the tether cord, hold the throttle lever fully pressed and crank the engine for a few seconds as Sea-Doo describes (the engine turns over to move oil but doesn't start), then extract again, two or three times, to get the rest of the old oil out. Follow your own manual; not every brand does this.

Put a rag under the filter cover. Remove the cover bolts with the correct driver and set them somewhere they can't fall into the hull. Pull the old filter and O-ring(s). Wipe the housing and cover clean and check for debris. Sea-Doo notes some engines use one O-ring and others two; the new ones come in the kit.

Coat the new O-ring(s) and the filter's sealing ring lightly with fresh oil. Install the filter and the cover, and tighten the bolts to the torque in your manual (they are small bolts into a soft housing; don't overtighten). In salt water, Sea-Doo suggests a thin coat of grease on the cover's mating surface to fight corrosion.

Pour in the oil through the fill opening with a funnel. Start with a little less than the amount in your manual, since some old oil always stays in the engine. Reinstall the fill cap and dipstick.

This is where most owners go wrong: PWC oil level checks are not like a car. Each brand has its own routine, so follow your manual. In general:

• Yamaha says to check with the engine at full operating temperature, and that anywhere between the marks on the dipstick is OK.
• Sea-Doo has owners warm the engine, rev briefly and shut off at that RPM, wait at least 30 seconds, then read the dipstick.
• The level often drops a little after the first run because the new filter fills with oil. Top up in small amounts until it reads correctly. Do not overfill.

With the flush water on, run the engine briefly and look at the filter cover and fill cap for leaks. Shut down, turn off the water, and look again.

Reinstall the engine cover and seat. If your PWC has a maintenance reminder on the display, reset it as your manual describes. Record the date, engine hours, oil and filter used in BoatMend.

Pour the old oil into a sealed container and take it, with the drained filter in a bag, to an auto parts store or a local recycling center that accepts used oil.