Another Oil Study. Interesting results indeed.

I found this very interesting. The good oils in this test are expensive in the UK, if available at all, but it at least gave me values for zinc and phosphate levels I should have. (1400ppm+)
I recently bought some eastwood additive and so looked it up, and it seems to have the right sort of amounts for a Z sump full.

https://www.eastwood.com/ew-zddp-oil-additive-4-oz.html