Defrosting and cold starting a small engine lawn tractor in subzero temperature -26f ; using a heat gun, battery charger and a waterproof tarp. It’s very important to use a waterproof tarp because your trying to create a balloon of hot air around the tractor. The heat gun throws out about 700F degrees, after about 2hrs the air in the “balloon” is about 85F degrees. The battery charger I believe is a must have to make sure the battery is fully charged. I like this Stanley 25A battery charger because of the car start feature. ****Do Not Do this if leaking fuel or fumes ****