Good ol' Wally mart SuperTech SAE30 oil is now rated at API SG and off highway Diesel use. It's got StarTech's zinc in it in heavy dosages. And check out that price.
"But API SG and SH were the last PCMO service classifications where the zinc level in the engine oil was any reliable indication of anti-wear performance. ... API Classifications SL, SM and SN all contain reduced levels of phosphorus and sulphur, and therefore zinc, for catalyst protection."
"But API SG and SH were the last PCMO service classifications where the zinc level in the engine oil was any reliable indication of anti-wear performance. ... API Classifications SL, SM and SN all contain reduced levels of phosphorus and sulphur, and therefore zinc, for catalyst protection."