The new formulation of Rotella T 15W-40 that meets the CJ-4 spec contains 1210 ppm
zinc, the max allowed for CJ-4. If I recall correctly, it used to be about 1400. 1210 is plenty.
http://www.machinerylubrication.com/...up=Lubrication
It is my understanding the companies like Crane and Comp Cams have changed hardening processes in respoonse to lower phospated ash/zddp.