Mine was not one of the models sold as "flexfuel" - I'm told that the programming is the main difference in the flex and standard models. I would like to run E85 and eventually E100 - I have a fuel ethanol license and would like to make my truck scream on American Made Energy. There are particular ...

I have a '02 GMC Sierra 5.3L. If running E85, will I need to configure anything differently than the settings already there for the 93 octane tune? The pump says 105 octane for the E85. The car was not marketed as the flexfuel version, but I have been told that it will run on ethanol as long as fuel ...