Ethanol blended gas (good or bad?)

Yeah the cans used to say add one quart of marvil mystery oil to each 20 gallons of fuel. Now they talk in oz, like 1 oz to each gallon of fuel. The cats must not like the stuff---so it has to be good, lol

Trans fluid is cheaper. marvil mystery oil claims its not as good.

With this super clean no lead-suffral, etc the gas needs something. Not sure if adding any oil can help stop detonation