Engines wear out primarily because of abrasives. There are other types of abrasives than dirt. Abrasives are things that are in places they shouldn't be. The main thing is to filter that stuff out. We can't stop it all, but with premium products we can minimize the effect.
Coolant has a limited lifespan due to degradation.
It eventually forms acids that cause system damage. Unfortunately, this is a little understood fact. Hoses and O rings can be damaged by degraded coolant. On the C series one can add chemicals to slow the process. There are really no problems, from a Cummins engine point of view, to exhaust brakes.