[dmsfrr]

Originally Posted by JimNNN

. . . I'm using STP oil treatment with the ZDDP added. Can you think of a better option? I notice that there are some other ZDDP additives out there, but the STP seems to be what's readily available at most stores.

A quote...

Modern heavy-duty diesel engine oils have lots of ZDDP additives and will be marked “CI-4 or CI-4 Plus” Diesel oils also have additives that pass all gasoline engine performance tests. Some racing oils also have adequate amount of ZDDP.

from this link...
https://www.ctci.org/engine-oil/