Goodbye Crane Flat Tappet. I hardly knew ye.

Yes, zinc does matter...but more specifically, it is the phosphate molecule that attached to the zinc that saves your bacon in a flat tappet engine...the shiny zinc just gets all the credit. With that, the problem with oils and additives you can put into your oil lies with the balance. If you have a high level of detergents (that want to get rid of the phosphate) and you add zinc (usually in the form of ZDDP) they could somewhat cancel out from a chemical protection perspective.

TMI, I know...but I thought I would throw my 2 (nerd) cents at the conversation.