Zinc Rich Oil for Flat Tappet Cams

A few are having trouble with some of the concepts of how oils, straight grade and multi-viscosity relate to temperature. 71DodgeDemon340's charts are excellent, but are extremely detailed, so I'm going to put out some basics.
Oils thin as they are heated, and thicken when cooled. That's just common sense, and we all get that. The difference is that multi-grade oils do this at a slower rate, which allow them to flow cold equivalently to a SAE 10W at 0*C, and yet have the same thickness as a SAE 30 at 100*C.
Please see the attached chart for a simplified illustration. I've used versions of this hundreds of times over more than 30 years, and it has never failed to help folks understand.