Why is so necessary to exclusively connect Amsoil (in a bad way) with Four Ball Test. Take a look at: Mobil data and (suddenly) all of us will reveal that (even) so well known Mobil use that test. (I am still browsing and there will be more manufacturers and related facts).
So, let's (all of Mobil users) turn back to Mobil. Immediately!
All of us, in final stage (after exploring documentation, checking testimonials and discussion if it's possible) use non (far of, actually) standardized "personal" methods to evaluate products. They are mainly based on very subjective "principles" (sounds, hearing, seeing, feeling, sniffing, ...) and achieved results are determinants for accepting or rejecting. That "method" is better than any of standardized?
So what would be customer's loss of having results of one more (standardized, in contrast) test even if it is not explicitly related to that product?
Even if that test is exclusively made for greases it would be somewhat plausible. If we simplify things: grease is synthetic oil with thickener!