Here is a quick write-up on performing a fluid change on your NP231J transfer case. It's quick & easy, and will go a long way toward keeping your Jeep running smoothly!
Use a 30MM socket to remove the FILL PLUG FIRST
to make sure you can refill it afterward.
Now drain the fluid. You can use an old piece of cardboard to keep the fluid from filling your skid plate. I was using a shop lift at the time, so I elected to skip the cardboard (regretfully) this time.
Let it drain until it drips out in individual drops. Then reinstall the drain plug.
I use the spout top from an old gear lube bottle on the top of the ATF quart bottle to refill the T-case.
I also have a spiffy little screw on funnel that makes refilling the quart bottles easier!
Refill it until it comes out of the fill plug, this way you'll know it's full!
PLEASE BE RESPONSIBLE
& recycle all old fluids!