Oil change with full flush?

I ve always used Rotella and never noticed any pressure drop. I put 4000 hours on a pair of 3412Es using rotella, boat sold with 5400 hours and passed survey/oil analysis without issues. Just a puff of smoke on cold starts

I’m attempting to download a technical paper 1.5 MB PDF (Engineering Test Results) on motor oils with no luck. Keep getting a note that file is too large, suggestions? Paper totally changed my understanding / opinions of oils.

Exactly. No engine manufacturer makes their own oil.
All the oil is made by someone else to their specifications and private labeled.
And I’m sure that goes out to bid so it probably changes over the years on who’s making their private label oil.
Could be Mobil one year , Shell or others the next .
Personally I use Valvoline 40 weight
Which I get from Napa under their private label.
It’s been doing just fine for the past few years for me .

The 75 page paper I attempted to download explains that oil is oil (more or less). However, the “additives” are key, making a profound difference in performance. While Cat may use a Mobil base, their additives are likely proprietary to the Cat blend and only available in the Cat oil. The author does extensive laboratory wear testing comparing various oils to illustrate this very point.

Main take-away from my reading; Sams Club oil is probably not equivalent to the Cat Oil.

if anyone is interested in the paper, PM and I’ll forward a PDF

No doubt you , given your profession, you should use the factory labeled oil for all your work an nothing else unless the owner tells you other wise . CYA. I would be doing the same thing if I were you.

Ole Cleanslate on the other hand has to watch his money very carefully , so I will save where I think it's rite. BUT I have professed to be a Michael Stivic at time her on Y.F. and get myself into boat trouble by being to cheap and not so smart.