Many cam companies I have seen recommend not running an API labeled oil. There's plenty of Hot Rod/Z rod stuff out there decent priced. I run amsoil z rod in my 65', just changed to Gibbs in the race car.

In what 04/05' Rotella, and all diesel oils had to meet CJ4 classification and run more detergent and less sinc. They still have like 1200 ppm of zinc but all the detergents will displace some of it on the wear surface.

We have problems getting oil for old Detroits and some Cats because they can't run the new stuff meant for EGR/DPF stuff.