yet, wayne, you let pass the claim of the poster whose handle is "steve" when
he said commercial fishing boats have their engines "torn down" after nearly
every trip. 4,000 hours is nearly six months continuous running time, while
8,000 hours is over eleven months.

do you suppose "steve" didn't know what the term "tear down" means?

The normal rebuild interval for a naturally aspirated (non-turbo)
Detroit 671 is in the range of 4,000 to 8,000 hours for an engine in
moderate service, that is well maintained, and has not experienced
cooling issues, etc.