i'm not advocating any particular oil, or slamming any. there's just a TON of marketing that goes on in the lubrication business. i don't claim to be any expert but i saw this FIRST hand and was somewhat shocked at the time. lubricants have to meet certain specifications imposed by both the government and API. if an oil has a given certification it must meet the specifications for that certification. not all oils had their ZDDP levels reduced the same amount depending on their rating. for the most part all oils had to reduce their content of certain additives. to make up for this they modified their additive packages in an effort to offset the loss of the restricted ones. below is a link to little info from an article. the link i posted to the BITOG is probably the best place to become somewhat educated about lubricants. afaik the shell turbo t is still around 1400ppm

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