[Moreair1]

I have the dsx flex fuel sensor, i have the stock table tuned to 91 octane and then the flex fuel table set for e85, there is night and day difference between how the car runs when e85 is in the tank, the nice thing with the flex fuel sensor is not all e85 is the same unless your getting it out of a drum so the computer will adjust to the percentage if tuned into the computer correctly, as far as why the shop may have recommended that way i have a few theorys but ill let ted answer is since his answer would be correct vs a guess