I am going to be leaving for training for the army in September, I will be gone for about 6 months. The Jeep will be sitting in the garage over the winter; so what (if anything), should I do to it before leaving it un-driven for that amount of time?
1998 ZJ 4.0 Stock 225/75R15 General Grabber AT2
I'd just add some Sta-Bil to the gas, make sure there's enough antifreeze in the cooling system, and disconnect the battery cables. Six months isn't that long to sit. If it gets really cold where you are and you usually drain and refill your coolant for the winter you should do that before storing it.
Just disconnect the battery and you should be fine. You may want to fill up the gas tank to prevent condensation, but I've seen cars start up after having sat for years and years with nasty gas. Some people go to great lengths to put their vehicle up on jack stands and other craziness, but it's a Jeep, not a person.
I'd put it on stands or you could flat spot the tires. Unless you don't care for the tires then leave it.
Flat spots on the tires really?
I used to get flat spots on my pickup truck back in the 60's before the steel belted radials were invented, the flat spot would cause a thumping for the first mile or so then go away, it would occur after only about a week of sitting,
I wasn't aware of anyone having that problem with modern tires.
Six months isn't long enough to worry about anything except the battery as mentioned would be a good idea to disconnect, maybe a cover too, or just some blankets and sheets towels whatever just cover it.
I have some pretty low mileage (<1000) Kumho Ecsta Supras on the front of a project car. After it sat about a year my dad borrowed them to get his car aligned and he said they had some bad flat spots. I was planning on throwing them on the back and doing a nice long burn out to get them hot and round again. I've heard that the more performance oriented tires are still prone to flat spots maybe because they use soft compound. I think the stock Jeep tires and upgraded off road tires are probably pretty good.
Pack the tank full of gas and add some stabil to it. You do not need to hang the suspension. The way tires are made these days they won't flat spot. My Mustang sit's 90% of the time, I never hang the suspension on it.
My Jeep sat for a year with 1/2 a tank of gas in my parents garage while I replaced a blown motor. No flat spotting on the tires, gas was fine. I'd disconnect the battery and put a tender on it but that's all you really need to do.
Tires should be fine unless you have Bias ply tires which i am not even sure you can get anymore. Do what eveyone else said and use some stabil but what would be better is to have someone go drive it every other week or so.
Air up the tires to 40-45psi to avoid flat spotting (and maybe a flat tire if any have a slow leak). Full tank of fuel with some stabil. Disconnect battery. Couple boxes of D-Con mouse/rat poison on the floorboards, rag in the exhaust pipe and intake tube to keep rodents out. Put some drip pans underneath it unless it really doesn't leak (who are we kidding).