Picked up a mower a few weeks ago, and it has about 2 gallons of gas in it, and it was in there when they pulled it out of storage, so I don't know exactly how old it is. They say it's stable, and it doesn't smell too old to me, but I don't plan on using it for at least another month. Should I completely drain the old fuel and put fresh in when I am ready to do so? Or should I just run it a few minutes every week? What would you do?