All of that info, but a picture of a brand that has been stigmatized for years as having the crappiest oil. I would even use Quaker State to coat a wok, let alone trust it to protect my engine.
In true internet fashion, only 5 comments separate complete contradiction of ideas. One person says any oil is fine, another says this oil sucks. One thing is true: it's always possible to find a supporting opinion in an Internet oil discussion! 😁
Or maybe talk about the lack of zinc in modern off the shelf oils that will help to give you flat lobes on a flat tappet cam. I have used both, and settled on Shell Rotella in my classics. High zinc content, lower price, and is more than good enough for a gasoline engine when you consider that it is a go-to for MUCH harder working industrial engines.
The reason SO many flat tappet guys, including myself, use it is because you no longer have to buy an additive on TOP of oil to get the pressure additives necessary for a flat tappet engine to work without wiping the lobes. This is ESPECIALLY critical when you are running higher valve spring pressures which are pretty much necessary with a decent cam (not necessarily radical, but with the more aggressive opening and closing ramps). So to answer your question, yes, it was designed for industrial engines. But think about the following: Industrial engines see MUCH higher stress/loads placed on them. Now think about how little of a load your typical classic car engine is put under by way of comparison.
More succinctly put, your bearings, cam lobes, oil pump, have no real idea that diesel engine oil is going through it with the exception of having the zinc levels back to what they were and SHOULD be if you are running a flat tappet cam. Roller cam engines don't need as much ZDDP as flat tappets because a) the cam is much harder and b) you now have a roller following the cam lobe. The same rule applies for overhead cams engines as well. No need for the higher ZDDP levels as your cam follower is usually a roller design.
Also, the reduction of ZDDP was due to the fact that it is much harder on catalytic convertor.