Forum Discussion
ScottG
Apr 11, 2019Nomad
ktmrfs wrote:ScottG wrote:
Rotella and Delo for diesels contain zinc to prevent wear of flat tappets although the level of zinc has been reduced as of late. Zinc will cause premature fouling of the oxygen sensor in vehicles equipped with them.
depends on which formulation you use. I've seen Delo and Rotella that is both C and S certified for the latest ratings. I believe that Rotella T5 is only C rated, at least that is what I recall when I last bought some.
If it is S rated for the latest S rating SJ?? then it has reduced Zinc.
With the switch to roller cams on OHV engines and the increase in OHC engines, few of the new vehicles have a flat tappet cam. But lots of cars through at least the 90's do.
That's what I wrote: "the level of Zinc has been reduced as of late".
Any level of zinc is bad for 02 sensors and that's why it has been totally removed from all gas engine oils for modern cars.
(Yes, I know there are specialty oils with zinc added for old cars)
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