Over the Counter Zinc Additive
Roller lifter cams don't need much zinc because the rollers have very little friction as they travel around the cam lobe. A regular lifter has drag or has to slide over the lobe.
This depends on how aggressive a roller cam is being employed, it can put a much more significant side-load on the lifter body in the bore, a race roller's approach to the
tappet & rate is pretty extreme so protection there IS something to consider. It is also true that break-in is the primary concern on a flat tappet because it may drag/
slide,
it does not do this normally!, once broken in the lifter is supposed to spin freely in the bore w/the rotation of the cam lobe which is tapered to induce said spin in
conjunction w/the convex surface on the base of the lifter. This taper/convex face system is also what is supposed to keep cams w/o retaining plates back against the
block face at the cam gear. Yes, Chebby's cams were junk and half a bazillion 305's ate the exhaust lobes alive, nothing to do with the oil. 4100 Caddy's did the same,
but there were ton's of 302's, 318's and older Chebby SB's that were having absolutely -0- problems.