That's accurate as I understand it, Murph. But to extend it, if your car is designed for 91, 94 won't help, either.
Correct!
In my experience, cars that want 'premium' actually want 90 or 91. Cars that want 'super premium' want 93+. The only car I've ever been around that had that requirement was a Subaru Impreza WRX STi.
In my area, the common grade choices are 87, 89, and 93. Sometimes 92, very rarely 94. Thus, most of the time I go with 93. Not because 93 is better than 91, but because it's the only choice for my cars.
Oh, and one more thing.... if you're perusing forums about European cars and octane, and people are talking about gas grades of 93,95,98+, they're talking about European octane ratings. Euro gas doesn't have a higher octane content than US gas, it's just rated differently. RON vs. R/M, or something like that.... I believe that Euro '98' = US '93'
