The way the factories tell you to break in a marine engine should be similar to what would work for a car engine. All of them, Mercruiser, Volvo, etc say pretty much the same thing. For the first 10 hours don't run it wide open or lug it. Run it progressively higher, so for a while run at like 3000 rpms, then move up to 3500, then go back down to 3000. After the breakin change the oil and filter and you are good to go.

I just learned recently that roller cam engines (like the Vortec in my T) do not need the traditional running at 2500 rpm routine to mate the cam and lifters. I was always taught you don't idle an engine for for the first half hour or so, but the guys on here educated me that roller cams don't have that problem. As for oil, I have started running Shell Rotella T, and it seems to be doing a good job so far.

I'm sure some of the really smart engine builders on here will have their own personal thoughts on how to best do it.

Don