> I may be wrong, but I was under the impression that Shell Rotella oil
> was still using the high zinc (SAE SJ rating) for some time after the
> automotive oils had switched to the new low zinc SM rating, but it now
> has the low zinc rating as well.
They did reduce ZDDP content slightly a few years ago. The document I have
indicates that the 'old' Rotella T CI-4 had 1400 ppm zinc, while the 'new'
Rotella T CJ-4 has "only" 1210 ppm zinc. But that is still almost twice
that allowed for SM oil.
And FWIW, they claim to have other, extra additives that make up the
difference. The same document claims the new oil now contains 35 ppm of
Boron while the old one contained none. That may or may not actually mean
anything of course, but I have seen boron-based additives mentioned in the
search for a ZDDP replacement.
-- Randall
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