Stop in for a cup of coffee

Been used for decades in big diesel engines..

yeah, I'm not saying its bad but its just interesting that the oil known for zinc and having all sorts of minerals an stuff in it has less than other ones.
The Delo 15-40 has 1-2% of zinc in it

Formulations have changed.
I was using Rotella T 5W-40 for the Grand Wagoneer. Then changed to T6 because the formulation changed even though its "Rotella'.
Somewhere around 2017-18 the formulations were changed again.
With the new engine in the Wagoneer, the Ford Diesel oil was about the only conventional I could find with a moderately high ZDDP based anti-wear package. So that's what I went with. Its rebuilt so plenty happy with 10W-30.

By next winter hopefully I'll have identified a decent 5W-30 synthetic to switch to.
Standard cam so the valve spring pressures are nothing crazy.