Rotella for GAS Engines

ktmrfs 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)

But does the Rotella that is CK rated but no S rating have reduced/no zinc levels or does it still have higher levels of zinc since it is only C rated, not SN rated for gas engines.

On the website T5 and T6 do not carry a S rating, however there is a T6 "multivehicle" version that carries a SN rating and a CK rating.

So at least the SN rated T6 must have low/no zinc, don't know about the CK rated ones.

The current Rotella API CK4 oils has essentially the same amount of Zinc and Phosphorous and the previous API CJ4 oils with the exception of the T6 5W30 oil like you listed.

Delo and Delvac are the two oil brands that choose to reduce Zinc and Phosphorous to their diesel oils so that they can also be gas engine rated. I think this was a bad choice on there part.