Kind of an odd viscosity unless you have classic cars or live in a hot climate

He says "old iron", that could mean anything, but in my personal opinion it's probably for the best to bump up a weight once a car gets over 150k on the odometer. You get a little thicker film to compensate for wear, a bit higher viscosity to cut down on any leakage, and the same low temp performance.

I would not play around with it on anything with VVT, but it's a pretty common "hack" for pre-2010'ish motors and probably even a good idea.

Florida. 89 Dodge p/u, 92 Buick, 96 Toyota and my son daily drives a 63 Dart. We have a 61 Sunliner I drive when the weather cools down.