[cleatus12r]

Thanks Longshot.

Read what he said, hampsterzone.

I have been a dealer tech for the better part of 10 years and I will tell you with absolute certainty that there are some techs who shouldn't even be checking air in tires. Your guy is one of them.

However, there is little to be said about the different "grades" of fuel except that just because it's "premium", doesn't mean it's higher quality. "Premium" is simply a name that the fuel stations give the fuel....maybe to sell more of it for no reason....who knows? The octane rating is (in the simplest terms) the fuel's resistance to detonation. The higher the number, the slower the burn, and the more controlled the flame propagation is across the top of the piston during combustion.

Running 91/93 octane in your truck with stock programming is a waste of money, simply because your truck's stock programming is not able to recognize the "knock resistance" of the fuel and the ignition timing will be far from optimal to actually use the slow-burning traits of the fuel.

Poor fuel economy and sometimes high engine temperatures can be attributed to using higher than recommended octane fuel because once the ignition takes place, the slower burn of the high octane fuel causes the cylinder pressure to remain lower and occur later in each of the piston's travel. As far as hurting the engine? Not likely at all.

Rest assured, young grasshopper, that the ignition timing has been adjusted to make better use of 91 octane fuel. There's not any appreciable difference in different octane fuels, so just because there are "grades" from 85 to 93 out there, doesn't mean that any one is better or cleaner than another.