Ethanol is hygroscopic, which means it attracts moisture. That's why it's not shipped in pipelines. It also Evaporates faster than gasoline, which means if it sits in a vented tank the blend is going to change over time. I've had bowls rust so badly I've had to replace the entire carb. With E blend gas in them. I run E10 in my pickups every day, but I won't run it in a small engine if I can avoid it.