A Cummins Diesel field trainer was teaching a seminar on engine maintenance to a bunch of yacht owners at a marina where I used to do a lot of electrical repairs. When somebody asked him how long a Cummins engine would last, he replied "Long enough to eat 10 pounds of dirt!". He was emphasizing that regular oil and air filter changes have a huge impact on engine life. 10 weeks- - - -or 10 years- - - -or 50 years- - - -it all depends on how clean the owner keeps the engine.

Adjusting Babbit bearings with shim stock was a routine job, usually done during a "ring and valve job". The piston rings in the 40s and 50s were the weak point, and they usually failed long before the rod and main bearings did. Precision insert bearings can't be shim-adjusted (or at least it shouldn't be attempted), so keeping the oil clean and dust out of the intake will be the determining factor for bearing life on engines since the mid-1950s.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!