So how will I get the maximum use from my 5.7 liter GMC in my cruiser?
I'm running Amsoil 15-40 marine diesel synthetic oil in it and will
report when it dies.

Another question: Which is easier on the engine, ten miles up on plane
for a half hour at 3600 rpm or ten miles for an hour and two thirds at
hull speed at 1600 rpm?

Capt. Jeff