there is a tester that you can buy from briggs and strat. it basically is a graduated cylinder you fill up with amounts of fuel and water shake and let sit. you then can watch it seperate if there is ethanol
no more debate if it does or doesn't.
FYI I am running shell 91 all the time and have been for ever.
Not to beat a dead horse...... too hard.
Every time I filled my truck up at Costco lately I asked about the Ethanol in the premium. Some didn't know but the one attendant said NO, 100% NO the supreme does NOT have any Ethanol in it. So fill those sleds up and save a few cents per L.