Boats don't have odometers. Engine hours are the only measure of wear, and they drive every service interval. Oil changes, impeller replacement, lower unit service, spark plugs, fuel filters. All hour-based. All easy to lose track of when you're focused on time on the water.
Most four-stroke outboards need an oil change every 100 hours or once a year. Mercury's FourStroke schedule replaces the water pump impeller every 300 hours or 3 years, and many owners swap it yearly in salt or silty water, so check your manual. Lower unit gear oil runs on the same 100 hours or yearly cycle as the oil. LookOver tracks all of it by hours and dates, with compound reminders that trigger on whichever comes first.








