911-997

That answers my question.

Thanks all for feedback

curtisr

I whole-heartedly agree with your advice regarding late model cars but wonder a bit about the damage to catalytic converter comment. Why? Certainly not from my own empirical efforts but it might indeed be a case of 'cover your a$$' on the part of Shell et al.

The 'damage' seems to be a function of

• zddp content -- the more there is the more the surface inside the cat can be 'poisoned'
• how much oil is consumed by the motor
• how many times the PCM reads what's going on inside the cat; that is, a low-efficiency reading regarding ability to store O may be returned which will in-turn, change the mix settings...

Still, the S rating, whole-fleet approved, higher ZDDP levels associated with 40 ratings makes it a good choice. Except in the cold!

theiceman

I was under the impression that even the rotalla and other diesel oils have also been reformulated with removed zddp. This is why I no longer put rotella in my car and stick with kendall racing or brad penn racing.

( I was also under the impression high zddp oils had to be labelled " racing oils" now not designed for street use , but alas \I may have dreamnt that up )

but I am talking strictly for air cooled engines now.