I have a 231 tc, bought used, 100,000 miles, 92 xj
Should I change the transfer case oil?
I picked up a quart of Valvoline synthetic tc oil.
Which is the drain plug?
Fill plug?
Thanks

 

Yes change the fluid, it takes more than a quart, on the back of the transfer case there is two plugs, the bottom one is the drain plug and the top is the fill plug.

 

The plugs are 10mm hex head if I remember correctly. At least on my '00 they are. Take out the fill plug first. Why you ask? Cause if you take out the drain plug first and find that you can't get the fill plug out you are kinda up the proverbial creek. Should not be a problem but have seen posts from time to time where people have had some trouble.

 

I think it takes just over a quart of fluid.
Just loosen the fill plug first, then open the drain. Refill till the fluid is running out of the fill hole with the jeep as level as you can get it.

EDIT:
The older ones used a big bolt, the newer ones use a hex head.