@TallPaul
Well, maybe I do work in that industry. Maybe in another.
And yes, you can run differently, and yes you are right, your oil will behave differently. How differently? Well, that depends lot from your engine, fuel used, and of course, your personal driving style.
I have no experience with Valvoline, Maxlife or Durablend oils, as they are not common in Germany. Just looking at the sum parameters from the oil (Ca, Mg, S, Sulfated ash etc.) says nothing about performance. So even if I wanted to, I cannot say anything about the quality of these oils, because I have no data.
To make things worse, "synthetic" or a high price does not guarantee to have a good oil.
So, what are your worries ("... but for hard use more is good--to a point. What I am proposing is a mild additive boost for an extra edge.") that you want to use extra additives or European oils? Do you believe that this will help to increase your engines life?