your, right oil is extremely stringently engineered product, but to what end? Engine longevity or fuel mileage and emmisions? It's a fact that newer API SM rated oils have less anti-wear and anti-friction additives (namely ZDDP and Moly). Oil additives like Valoline Synpower oil treatment, SX-up, Lube Control, and Auto-Rx have also been very stringently manufactured for cars that need more of these additives that are no longer found in newer oils (like pre-98 contours that you buy used that may not have had the best maintenence records in the past).
