Quote Originally Posted by IC2
I wont use the more expensive gas at 30 to 40 cents more for 2 octane points(up to 89) or 50-70 cents more for the 93 for an experiment. My truck was built for the 87 gasoline which means the ECU is programmed for that stuff. I'll get a reflash of the ECU in a couple of months for any updates. On my Ford truck forums there have been threads on lower gas mileage with the 90/10 gas to ethanol blends but I haven't found an reputable on-line article about this yet. It does make sense that there will be a difference in combustion flame propagation in the engine. This propagation has to be modified by this amount of a volitile additive, 10%. I just am not sure which way. Unfortunately I just don't have enough information one way or the other to understand this.
In Austin 89 octane is 11 cents more. What you are missing is this. Sure the ECU of you fuel injected vehicle can operate with 87 octane but it will very likely provide more fuel due to the engine response. It's all physics, nothing more ...............

Kitz