[Brucelee]

Brucelee, what's the source of failure in this case? Is something breaking from stress or is it breaking from wearing out? I would bet that it's the former. You have to look at the cause for this to be useful information.

I believe that the amount of STRESS that you place on a motor contributes to it wearing our or breaking.

I don't think that there is any question that a bearing is stressed more at high rpms vs low rpms, all things being equal. Ditto, connecting rods, pistons, valves, etc.

That is why racing oil is developed, to deal with unique stresses that normal motors don't experience.