Tops around 250 and completes around 500.

Like to know: I heard these 250 top/500 bottom numbers for 525s too. Isn't this for motors raced and run hard? These intervals for 525s even if the motors used mildly?
Thanks, Andy

I was always told that top end or complete rebuilds at these hrs were for the guys who were doing weekend poker runs and pushing their boats to the limit every time out. Most of us don't push our boats like that therefore the hrs are irrelevant for top end/rebuild maintenance for the average high performance boater unless your always running at top rpm's.

The other problem is that with boat motors and esp salt water motors, it is usually not the engines fault that something goes wrong. I have rarely seen a motor just break, not saying it doesn happen, but not often. Usually it is something else that went wrong: cracked headers, corrosion on valve spring or stem, cooler leak, blown gasket, clogged pick up/strainer, bad fuel, etc.... and the list keeps going. Coming from a guy that boats in salt and has a lot of friends that do, I have almost never seen an engine make it to the original magic number that the manufacter claims.