Rotella for GAS Engines

FishOnOne wrote:

ScottG wrote:

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)

All API SN+ gasoline engine oils contain zinc. They typically have ~800ppm of zinc which includes the new Rotella Gas Truck oil.

The #1 reason for the reduction of zinc is to increase the life span of the catalytic converter.

well if zinc affects CAT life, why do the diesel CK oils have the higher zinc levels? Diesels have CAT's as well. If it affect O2 sensor I can understand, but not effects on the CAT.