How To Change Four-Stroke Outboard Oil and Oil Filter

Quality oil is the life blood of any engine, including four-stroke outboard motors. Checking the oil level regularly, and keeping up with the oil-change schedule, will help ensure long, reliable service from your outboard. Changing the oil is a pretty easy DIY task.

The maintenance schedule for most four-stroke outboards calls for an oil and oil filter change every 100 hours, or annually. If you put your boat up for the winter, professional technicians suggest changing the oil as part of preparation for off-season storage. Storing the motor with old oil can expose internal engine components to moisture and acidic combustion byproducts, which can cause corrosion. Check your owner’s manual for the recommended lubricant products for your marine engine. The line of Quicksilver Premium marine lubricants includes four-stroke engine oil for any outboard brand, specifically formulated for the unique needs of the marine environment. Quicksilver Oil Change Kits for Mercury FourStroke model outboards from 15 horsepower to 115 horsepower package oil, an oil filter, and a drain plug seal and complete instructions in a convenient box.

Pro Tip: Occasionally the oil filter gasket, a black O-ring, may remain stuck to the engine after the oil filter is removed. Always carefully check the filter sealing surface for the oil gasket. If you “double gasket" the new filter – screwing it on over the old gasket – it will likely leak oil and could cause engine damage.

In this how-to video, Scott Glorvigen of Wired2Fish and the Lund Boats Pro Staff uses a Quicksilver Oil Change Kit and some basic tools to change the oil and filter on a Mercury 75hp FourStroke outboard. For specific instructions on draining the oil and locating the filter on other outboard models, consult your owners manual. Always dispose of waste oil properly.