Anybody using Driven brand HR-2 oil in their slant?

Guys/Gals: My engine builder swears that this is the only oil to use in my newly rebuilt slant six in my 1974 Duster.

Nope, he's wrong about that. You'll see and hear all kinds of handwaving and spooky ghost stories about how y'just cain't get oil that'll protect an old engine at the parts store any more, so y'gotta-gotta-gotta buy this, that, or the other special boutique oil. HorseshÑ–t! The worst oil available today is leaps and bounds better than the best available 10 years ago, let alone in 1974 (or '84, or '94). Use any reputable brand of 5w30 oil in your new engine (there is no reason to avoid synthetic, but your engine doesn't require it), and a good quality filter; change the oil and filter at reasonable intervals, and scratch this off your list of stuff to fret about or spend unnecessary money on.

Good, dependable education on the matter here, and more discussion here and here and here and here and here and here and here.