I'm having a Ford FE engine built, and the builder strongly recommends hydraulic flat tappets for the best reliability. He's had good success with Honda Motorcycle Oil (GN4), which, from my research has less that the desired 1200 ppm zinc and 1000 ppm phosphorous.
Two oils that have historically been used for this type of application are Shell Rotella T4 15w40 and Chevron Delo 15W40. The information that I've found online on current configurations on these two oils has been confusing to say the least, so I decided to contact Shell and Chevron to get what they have to say about the current formulations.
I'll post more complete data later, but in a nutshell the Shell Rotella T4 15W40 still has acceptable zinc and phosphorous, whereas the Chevron formulation has zinc and phosphorous below 1000 ppm, but says their new anti-friction additives are still acceptable for flat-tappet applications.
Two oils that have historically been used for this type of application are Shell Rotella T4 15w40 and Chevron Delo 15W40. The information that I've found online on current configurations on these two oils has been confusing to say the least, so I decided to contact Shell and Chevron to get what they have to say about the current formulations.
I'll post more complete data later, but in a nutshell the Shell Rotella T4 15W40 still has acceptable zinc and phosphorous, whereas the Chevron formulation has zinc and phosphorous below 1000 ppm, but says their new anti-friction additives are still acceptable for flat-tappet applications.