How Do I Change the Oil in a Mercury Outboard?

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Your motor operator's manual, dealer and the Mercury Marine's website all tell you the dire consequence of doing your own maintenance--you might do it incorrectly. While it's true that improperly done maintenance voids your Mercury warranty, it's also true that the motor operator's manual gives you maintenance instructions, complete with pictures. When you can change the oil in your Mercury outboard yourself, instead of taking the motor to a dealer, the feeling of accomplishment is right up there with your first real kiss.

Push down on the lever on the rear of the motor cover and tilt the cover forward, lifting it from the hooks at the front. Set the cover aside and tilt the motor slightly, with tilt and trim control, to drain the oil into the motor's oil sump.

Return the motor to the upright position after about one minute, pull the dipstick out of the motor and slip the tube of the oil pump through the dipstick hole until it reaches the bottom of the engine sump--you'll feel the "bump" when the tube hits the bottom. Pump the oil out of the motor and into an oil drain pan with the oil pump.

Slide the drain pan beneath the oil filter. Wrap the strap of an oil filter wrench around the filter and turn the filter counterclockwise to remove it. Connect the flushing attachment to a garden hose and put the flushing attachment on the engine.

Use a clean cloth to wipe the mounting base the oil filter screws onto. Dip a finger into clean oil and wipe the oil around the new oil filter gasket. Screw the new filter onto the base until the base touches the gasket--tighten the filter one extra turn.

Remove the filler cap from the oil filler aperture and fill the engine with the amount of oil recommended in the motor operator's manual. Turn the garden hose on full force and start the motor, allowing it to run for five minutes. Shut the motor down, check the oil level and add oil, if necessary.


  • Always advise everyone in the area before starting the engine. Propeller strike injuries are serious at best and fatal at worst.


About the Author

Will Charpentier is a writer who specializes in boating and maritime subjects. A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. He is also a certified marine technician and the author of a popular text on writing local history.

Photo Credits

  • toy outboard motor image by pearlguy from Fotolia.com