To be honest, I'm not sure what caused the piston to seize. I had used the saw all day without a problem and then lent it to my brother that same day. I had about a quarter tank of gas in it and he swears he didn't add any gas to the saw. He just had a 10" tree to take out at then end of his drive. Well I get the call that he was using the saw and all of the sudden it just quit running and he couldn't get the pull start to work. That's all I know. It was about 50 degrees out so it wasn't like it was 20 below zero. I run the saw from april to october, I never have ran it in the dead of winter. I wouldn't think that would be such a drastic temperature change to burn up a piston.