A very good mechanic I know told me that the Chevron additive Techron really does keep fuel injectors clean. Since I have one of the most complicated outboard motors on the water, the Mercury Optimax 225, I should pay attention to that advise but it was directed at one of my cars and not the outboard. Most of the gas does come from the same place and most gas in this area has ethanol (alcohol) added. I will be filling the boat at Costco tomorrow morning with regular unleaded with ethanol...I think the motor will run just fine with it. I am more concerned about the oil than the gas. I do have a fuel separator filter.