Did AutoZone discontinue VR1 20w-50???...thoughts on Rotella 15w-40

One has to keep checking the "rating" - SJ, SM, SN, etc./CI, CJ, etc. Every time they change it, something in the formula changes. If it says it's suitable for the newest diesels, it may very well have reduced or very little zinc because it isn't compatible with the newer emissions stuff. It's not easy to keep up with.