Moisture is the enemy, and Ethanol seems to attract it. It also eats rubber parts on older vehicles. I don't believe the pure gas breaks down in a month, but maybe "pure gas" is something different than ethanol free gasoline? IDK and I don't care, how I maintain my 2 strokes has given me years of start every spring, and after initial carb cleans on non runners, no need for further ones. I also think ethanol content is different around the country, so maybe that has something to do with it. I don't ride every day anymore, (pouts) but the ethanol free works for me. Do what you want.