Originally Posted By: gfh77665
Originally Posted By: wemay
I often read how some feel the 'old SM' version of many oils had better additives or more additives, making the oil more stout. Do you consider API SM the high point in motor oils and SN a step back in wear with a nod to CAFE?
Thats an astute observation.
Not many here can wrap their heads around the fact oil evolution is driven by CAFE and emissions, NOT engine protection. For the record I am not claiming the latest oils are "bad" at all, (so please spare the hysterical retorts, thanks!). However, the earlier versions DID indeed have stouter add packs.
Royal Purple in particular took a lot of abuse by the uninformed here claiming it was "behind the times" with their strong SL oils, then when RP produced a SM oil, the same ignorant ones howled it was now "weaker", go figure.
Yes, SL and SM were probably the high mark for motor oils. Not all have the capability to understand this.
API SM/SN still have identical maximum ZDDP limits on resource conserving grades. Non resource conserving grades do not have the same maximum limitations.
There are quite of few friction modifiers are compounds which do not show up on VOA/UOA's. An tribologist will be able to provide examples for you. PCMO's do not go backwards in performance. Newer certifications require less wear, longer stay in grade operational viscosity, greater compatibility with fuel and seals.
We are often the victim of our need to feel in control. Concentrating on part of the lubricant such as the add pack feeds us this need.