We are all learners, so no need to ask to be schooled gently. I am not an expert, but let me try and add some knowledge. Our Mustangs were not built for E85 gas. Vehicles that do use E85 were specifically built to run E85. Our cars run best on pure gas, not gas diluted with ethanol. Power and gas mileage will go up with pure gas also. Pure gas is available in some rural farm areas where gas diluted with ethanol fouls farm equipment. I have never seen E104 gas, and only run 100 octane low lead in the airplanes I flew, so I have doubts that gas is 104 octane. Hope this helps. Good question and good luck! Let us know if you find more information.
1964.5 convertible and a 2012 Sterling Grey GT. 100 hp. and 412 hp. Go Bama, Roll Tide! 2015 National Champions! Clemson put up one heck of a fight!