There are also different seasonal blends of gasoline. With "winter" gas, there are more additives in it that make for easier starting in cold weather.

From personal experience from living in Northern Canada for many years, stored "summer" gas at times would not start my truck or 12 HP snow blower when it was colder then approx 25 degrees F. This also depended on other environmental factors such as humidity etc.

Once the fuel had been switched to winter blend gas, the engines would start and run much better.

I was told by more then one person who worked at the local refinery that produced gasoline that in general, the winter blend gas stores much longer then summer blend due to the extra additives.


This website explains it much further..