zinc oil useage?

I know this is going to be controversial, but the theory is zinc additives don't really make a difference with a flat tappet cam. It certainly doesn't hurt during break-in and you should continue to use the zinc additive especially for peace-of-mind. The truth is, the Jeep 4.0 has been been using a flat tappet cam forever and they do not use any special additives or special oil when it leaves the factory. Also, the owner's manual does not say anything about additive during oil changes (I've owned two Jeeps over the past 20 years) and when Jeep owners get an oil change at a commercial location, they never add Zinc.

(This is more of a curiosity statement than it is a scientific fact. Please don't beat me up. Just throwing it out there).