My 3.0 liter story is as follows. Was in a 1987 Starcraft Medallist 1601. Boat ran 43 mph. First oil filter change march of 1992. Went to launch after winter (Houston) and bilge full of oil, oil filter rusted through. Put new filter on and topped off oil. ran crap out of it until 1997 when I bought off my neighbor. Didn't have neutral for years as I disconnected the shift interrupter switch and pulling out of forward was hard enough to make it go in reverse. Installed the new and improved shift shaft busing in 1998 and had neutral again, lol. Manifold rotted out in 2000. 13 years of saltwater use but flushed every time, (800? hours). replaced bellows in 2012 complete waste of time as they were still good. replaced manifold pre-emptively in 2012, waste when I busted old ones apart they still had tons of life. Sold in 2018 for $4200 which is what I paid. Saw guy at boat ramp last week with it. Engine must have 3K hours on it.
Over life of boat we consumed over 17K beers lost an engagement ring, obtained 3 pinched nerves, 1 cracked vertebrae and dislocated shoulder. All injuries result of tubing behind it. I am a HUGE fan of the 3.0 liter. Boat fit in my garage negating storage. Used easily 20 times a year. Boat bottom was better 99% boats out there two scratches. Only outside when used. Smacked allot of underwater obstructions with Alpha 1 outdrive. Prop shaft wobbled, and did it well for 12 years. When sold still had original alternator, still used points and condenser. Had original spark plug wires, original block water pump, head never off engine. Replaced engine coupler once, guess I should have greased it. second oil change around 1998 had only 6 psig oil pressure at idle, change oil back to 22 psig. After 1998 replaced oil and filter every 3 years.