I have never owned a 6.2L in a pickup, I have several friends that have them. They run midgrade, which here is 87 they have never had issue. I have an LSA in my Camaro. I run 91 in that only, we don't have 93 octane here. I don't know what the fall off in mpg is, but unless the pickup can sense the octane level and detunes itself, there is no more energy in a gallon of 91-93 than there is in a gallon of lessor octane. The knocking, that is addressed by the higher octane. I don't know anyone here that has that issue but not to say someone hasn't.