How often should you change a fuel filter spin on look like a car oil filter on a Merc 150 efi. and how often on plugs? Any other maintaince other than lower unit oil?
If its a water sep filter, you should change it seasonal...or in the least empty it.
Gear oil, check it periodically through the season...change at the end.
Spark plugs, look for the electrode in the center to have worn away...if its fine, so are the plugs.
TMD