How to Change Oil in an Outboard Motor and How Often

To change the oil in a four-stroke outboard, warm the engine briefly, stop it, tilt the motor to vertical, and drain the oil through the drain plug or pump it out through the dipstick tube with an extractor. Replace the oil filter, refill with the amount and type of oil the manual specifies, and check the level after a short run. Many manufacturers call for an oil change around every 100 hours or once a season, whichever comes first, but follow your manual.

How to change oil in an outboard motor

1. Run the engine on muffs or in the water for a few minutes to warm the oil, then shut it off.
2. Tilt the motor fully down so it is vertical.
3. Remove the drain plug into a container, or use an oil extractor through the dipstick tube.
4. Remove the oil filter, wipe the mounting surface, oil the new filter’s gasket and fit it hand-tight plus the amount the filter specifies.
5. Refit the drain plug with a new gasket if specified.
6. Refill through the filler cap with the specified oil and amount.
7. Run the engine briefly, stop it, wait, and check the level on the dipstick.

Outboard motor oil type

Use the oil grade and specification in your owner’s manual. Four-stroke marine oils certified to the NMMA FC-W standard are formulated for outboards, which run under sustained load and moisture. Two-stroke outboards have no crankcase oil to change; they use two-stroke oil mixed with fuel or injected from a reservoir, usually TC-W3 rated.

How often to change oil in an outboard

Common intervals are around 100 hours or once a year for recreational use, with the first change after break-in sooner; see outboard break-in. Change it before winter storage so acidic used oil does not sit in the engine; see how to winterize an outboard.

Check the oil for warning signs

• Milky oil can mean water intrusion; see milky engine oil.
• A rising oil level that smells of fuel means fuel is getting into the crankcase.
• Metal particles suggest internal wear.

Tools and supplies

• The correct oil and a new oil filter
• A drain plug gasket if specified
• An oil extractor pump if the drain plug is hard to reach
• A filter wrench and rags, and a container that can catch the full oil capacity

Don’t forget the lower unit

Gear oil in the lower unit is separate and needs its own changes; see how to change lower unit oil and milky lower unit oil.

Related

See outboard motor maintenance, how many hours is a lot for an outboard and how to flush an outboard.

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