Quote:
Originally Posted by DLSTR
Yep. Its money. The oil if synthetic can go much longer.
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Probably not. Modern oils, synthetic or mineral, don't really break down or wax up, but the additives do, especially the viscosity index improvers. Likewise, the detergent additives are only marginally more capable than they were 20 years ago. The real improvements in oil longevity have been catalytic refining and development of the group II base stocks. Extended drain intervals to 6000 miles are based on the subsequent lower need for VI improvers with their shorter life due to shear, but detergents keeping combustion by products in suspension are the current limiting step.
Engine manufacturers and new car warranty providers watch these things closely. They're the ones that set oil performance requirements that the oil manufacturers follow, and they adjust their oil requirements and drain intervals accordingly.