That's kind of a long time to go on an oil change in a boat. I run the Royal Purple (full synthetic) and still change it every 20ish hours. I run the Merc Synthetic in my Volvo drive and change that when I change my engine oil at 20ish hours and stick the alignment tool in their just to make sure all is good.
James
The 100 hr. interval is dictated strictly by oil analysis. I don't like to cut it really close but 100 hrs. gives a really good clean analysis. It's really the best way to know the health and longevity of an engine that gets beat pretty hard.[/QUOTE]
How do you do an oil analasys? What does that cost?