"Steve Barker" wrote

the manuals already say 3,000 mi under sever service. 95% of people fit
this category.


Doubt it. Just thinking about my neighbors, of nine cars I know of. three
fit into the severe category. Of ten cars at work, two definitely do, two
are questionable. While my informal survey is not scientific, it is a far
cry from the 95% figure you use.

Fact is, no one can give an absolute number of miles for large groups of
people. The best way, of course, would be oil testing. Some cars to have
some soft of algorithm that does give you a time to change based on driving
habits, miles, etc. If the people that are covering the warranty give
higher miles, I'd say they are rather sure of the numbers.