How to Change Your Outboard Motor Oil and Filter, Part 1
With a four-stroke outboard motor, you will need to change the boat motor oil at frequent intervals. (A traditional two-stroke outboard motor doesn’t require engine oil because the oil and gasoline mix provides lubrication for the motor.) For a four-stroke outboard engine, it is generally recommended that the oil is changed once a year or every 100 hours of running time in fresh water, whichever comes sooner. For saltwater usage or if the four-stroke motor is run hard, the oil should be changed twice as often-for every 50 hours of running time and or twice a year if you are a frequent boater. A tip before you begin: have plenty of rags or absorbent pads ready to use during and after the oil change.
Pull the boat out of the water onto dry land and remove the engine cover (which usually is secured with one or two latches), setting it off to the side so that its surface does not become scratched. The top section of the outboard engine is called “the power head” and below it is the lower gearcase. Pull out the dip stick to assess the condition of the oil inside the crankcase. The drain plug is in the midsection of the outboard engine, and it will need to be loosened in order to drain the oil.
A table can be helpful to provide some leverage for the draining process. One technique is to turn the steering wheel so that the drain plug on the motor is facing inward, placing an oil pan on the table and under the drain plug to catch the existing oil. Back the drain plug out with the appropriate socket wrench, having a pan ready to catch the oil, because it will flow freely. Once all of the oil has drained, wipe up excess oil. Replace the drain plug, making sure it is secured.