re: OT mechanics: Vehicle reliability - Mileage vs Age

im not a mechanic but a chemical eng. I think there is a driving failure mechanism for age and for mileage.

For age, it's corrosion, swelling of soft goods (gaskets and o-rings) in oil or gas services, degradation of components, oxidation of electrical terminals, and things like that. I would expect that these are very slow and easily repairable. Storage conditions would play a role.

For mileage, it's the number of times each component has been actuated or stressed, thermal cycling, and accelerated corrosion or degradation due to more time at high heat. Moving parts are designed with a finite number of movements. I think this is the primary driver of reliability.

Anyway, thats my 2 cents.