Are the newer oils better than the older oils?
There is no doubt that oils have improved over recent decades, but unfortunately, technology changes and regulations change and all changes havent been for the better. The original SA grade was straight mineral oil (non-detergent and without additives) and SB contained additives, which could not be used in the earliest cars specified for SA. While it is true that SM oils are better for newer cars, they are not only not better for older cars, they are not good for older cars. Simply put, the newer and/or better oils of today are not backward compatible for older cars, primarily due to the gradual reduction of ZDDP starting with SG grade in 1988.
