We often discuss oils in relation to metal wear. For the last 27 years my only passenger-car-engine issues have been seals. Are there any standard seal-lifespan tests that are used to evaluate oils? I am curious about both wear at the elastomer/metal interface as well as non-wear (shrinkage, hardening, softening, expansion, cracking, ect.). If I "knew" that a given oil met specifications other wise, I would use seal lifespan as THE deciding factor in my oil purchases. This parameter is more important to me then all other "beyond spec" parameters. Problem is, I don't have a way to evaluate this parameter.