My 3500 has been parked outside for the winter all it's life, it starts right up and goes back to work just fine every April. All I've done beforehand is change the oil, air the tires and fill the tank with diesel with additive, I use Howe's. It's best if you can start it and bring it to operating temperature every couple of weeks but there have been years where mine was buried so deep in snow that I didn't want hassle digging it out so it went unstarted for over three months, still no problem. It's better if you can park it under cover. I also scatter sheets of Bounce dryer papers in the cab and under the hood, it keeps mice from moving in and messing with the wiring.