Since owning my boat (2 seasons) I've kept the engines (Mercruiser 5.0 MPIs) filled with a good, pricey synthetic oil (Amsoil 15W40).
It's probably complete overkill to use synthetic oil on this boat. The engines are raw water cooled and will probably rust out long before any internal engine part wears out.
The only reasons to keep using it are: (1) it's only about $25 difference from good, dino oil (like Shell Rotella T) per season, (2) it's probably giving me a few HP, and (3) it may be increasing fuel efficiency (and if I can save 6 gallons of fuel in a season, it pays for the oil).
Should I stay or switch?
It's probably complete overkill to use synthetic oil on this boat. The engines are raw water cooled and will probably rust out long before any internal engine part wears out.
The only reasons to keep using it are: (1) it's only about $25 difference from good, dino oil (like Shell Rotella T) per season, (2) it's probably giving me a few HP, and (3) it may be increasing fuel efficiency (and if I can save 6 gallons of fuel in a season, it pays for the oil).
Should I stay or switch?