I am going to be leaving the country for 5 months and need to store my bike in a unheated garage.
It gets pretty cold here during the winter (0 degrees, sometimes a little colder)
I am wondering what I need to do to keep this thing happy for when I return.
Fluids, additives ect.?
Just change the oil before you put it away, inflate the tires to 40 psi each to prevent bad flat spotting, if you don't have both a front and rear stand to lift the tires off the ground, and add Sta-Bil to the gas tank in the proper amount for how much fuel you have in the tank, and make sure you run the engine long enough that it gets into the fuel injectors so that they won't clog up.
BC.
Winters here in NH get cold sometimes. :)
Last winter I forgot to put the battery tender on the 620 and didn't put fuel stabilizer in.
It started up just fine this spring.
As stated above, you should put in fuel stabilizer and put the bike on stands or overinflate the tires, but for most people the most important thing would be a battery conditioner.
Apart from that, make sure the parking brake is on good and strong, top up the radiator, and drain the blinker fluid and you should be fine.
You could also plug/block your airbox and exhaust to keep moisture from entering the engine. This is from the Hayne's manual but I'm not certain how critical an issue it is.
You might consider fogging the motor.
http://www.amsoil.com/StoreFront/fog.aspx (http://www.amsoil.com/StoreFront/fog.aspx)
You don't need to get that brand. The description of it is why I posted the link.
I had a corrosion issue with my monster this past winter.