Looking at the maintenance schedule for the 2012 JK's it shows that at 32,000 miles to just inspect the level of oil in the transfer case and at 64,000 miles to finally change it out. My old TJ and LJ had it at 60,000 miles to change, but my ZJ had it at 30,000 miles. I can see the ZJ since it was Quadra Drive. Now if you drive off road your going to put a little more of a load on the transfer case than just driving to the mall. And No, driving over the parking curb at the mall does not count as driving off road. I generally don't put a lot of miles on my Jeep, but they are mostly in town, or off road, so if I'm going to spend the time crawling under the Jeep just to check the level in the transfer case. Spending a little more time and changing it out is worth seeing if I have anything going wrong inside the transfer case. It is also a good idea to inspect and at least drain out a little from the bottom if you have been playing in the water for any length of time. I know the breather tubes are located higher on the Jeeps, but you can still get stuff in there.
Additional
Parts:
(2) Quarts ATF +4
Tools
Needed:
18mm Socket
10mm Allen head Socket
Ratchet
Oil Pan
Rags
Bottle Pump
or spout
Floor jack(?)
Inspecting and Changing Oil:
1. Make sure your parked on a level surface and block the tires front and back. Set the parking brake. You are going to be laying under Jeep.
2. Support your transmission skid with the floor jack if you need to. I just held it with my shoulder while I removed the last 2 bolts. Remove the 4 bolts holding it in place with an 18mm socket. Remove the skid.
3. Put the Oil pan under the back side of the transfer case and have a few rags handy. When you remove the lower plug the oil will shoot out, so make sure you have the pan far enough back otherwise you may be on the receiving end of some splashed oil.
4. Remove the upper fill plug with a 10mm allen head socket. You may get some oil flowing out at this point. If it gushes out you could have a problem.
5. Remove the lower drain plug with a 10mm allen head socket. Finish removing the plug by hand and hopefully your aim is good for the oil pan. If not grab those rags. This is why we wear safety glasses. Though ATF+4 does leave a funny taste on your lips.
6. Let the oil drain out. Once it has finished draining reinstall the lower fill plug with a 10mm allen head socket.
7. Install the bottle pump or nozzle in the bottle of ATF +4. I got tired of pumping liquid and there is enough room to use a flexible spout on the bottle. Insert the other end of the pump into the fill hole on the transfer case. Pump away. Stop once the fluid starts to flow back out the fill hole. This should take about 2 quarts.
8. Once you get a slow trickle of oil out of the upper fill plug, reinstall the upper fill plug with a 10mm allen head socket.
9. Clean up any fluid that leaked onto the transfer case and floor.
10. Reinstall the transmission skid with an 18mm socket.
