zinc oil useage?

Some oils are dual rated, carrying both the C & S (diesel and gas) ratings such as SN, CK-4. Many Rotella grades carried dual rating for decades. What the new FA-4 diesel oils came out a few years ago, some oil companies, including Shell, chose to stop the dual rating. Even though some oils may meet both ratings, there may be much better oils for a certain application.

I've heard Shell may be labeling Rotella containers with the dual rating again. But since they're paying me to not work now, I'm not up to the minute on their offerings.