The gas in the picture was purchased in mid-June and this photo was taken last week. So that's less than 60 days. It was treated with Sta-bil 360 fuel treatment for ethanol (at time of purchase) and sat in my dinghy at the dock, subject to rain/humidity and day/evening heating/cooling.

This is for a 4-stroke engine -- so no oil was mixed in. This is straight gas. As you can see this fuel is totally shot. Fortunately I didn't even try to run my engine with it (switched it out). For any small engine I switch out any unused ethanol after 30 days and always use stabilizer at time of purchase.

I poured some into a gravy separator and let it sit for a while. Here's what it looked like after it clarified. I think that's a mix of alcohol and water at the bottom (not sure what it is, really). I left the bottom "stuff" out to evaporate, and diluted the top stuff into a nearly full car gas tank. .