I'm looking at the fact that after I replaced the seals in my 92's injection pump ,and I started using PS at that same time, that the pump didn't start leaking again, like it did when I ran an untreated tank of ULSD through it when it was first introduced. I can feel the difference because when I switch from the white in the winter to the gray in the summer, I get a slight little boost in power because the gray bottle has a higher cetane rating. You could say that that's "summer blend" fuel, or it's "just in your head", but with the power rating of that truck, it's very easy to feel even the slightest difference in power. And I'll throw in the fact that I can also hear the difference because in the winter neither of my truck's rattle as much on start up from the cold as they did without an additive, and the tractor is the same way so far.