Honda outboard manufacturer recommends changing an oil filter every other oil change. We recommend replacing it with every oil change. The expense of an oil filter is minimal and the extra cost keeps the motor oil clean, which is critical for prolonging the life of the engine. 

The oil and filter on a new or rebuilt outboard motor should be replaced after the first 20 hours. After break-in the oil and filter should be changed after six months or 100 hours, whichever comes first. It is a good idea to replace an oil and filter if the motor receives a lot of abuse. 

Basic oil and filter replacement procedures

1. 1. Run motor until it reaches normal operating temperatures so that oil can drain more efficiently. Do not run engine without a flushing device attached. 
   2. Position engine upright at 90 degree angle to ensure the motor oil drains.
   3. Remove drain plug cover to access drain plug (on equipped models). 
   4. Models equipped with a drain plug cover can use it as a guide to drain oil. 
   5. Place a sufficient container underneath drain plug to catch used oil. 
   6. Loosen drain plug enough to loosen the plug by hand. Finishing removing plug by hand. Quickly remove the plug from the drain hole and allow the oil to evacuate.
   7. Use an oil wrench to remove the oil filter from the engine. It should be noted that some models do not use a disposable oil filter. 
   8. Refer to the motor’s factory service manual for oil capacities and how many quarts/liters the engine takes.
   9. Clean the oil filter mating surface with a clean, lint free shop rag. 
   10. Apply a small amount of clean motor oil to coat the new oil filter gasket. 
   11. Place the oil filter onto the housing and hand-rotate it until the gasket touches the mating surface. Then screw the filter an additional 1 to ¾ turn by hand. Do not use an oil filter wrench to tighten the filter. 
   12. Refer to the service manual oil capacity and viscosity. 
   13. Upon adding the engine oil, use the dipstick to verify the correct level has been achieved. 
   14. Start-up the motor and allow it to operate for 1 minute. Make sure the flushing attachment is connected. 
   15. Turn the motor off and allow the oil to settle back into the oil pan. 
   16. Re-inspect the oil level. If the oil is below the recommended amount, add oil in small increments until the proper level has been achieved. 
   17. Dispose of empty oil bottles and used oil at an oil recycling collection center. Never pollute the environment by pouring engine oil onto the ground or water. 

It is strongly recommended that you download a factory service manual for your exact model and year Honda outboard engine. Always have a manual handy when performing maintenance and repairs.