[MagicRat]

Call this a blessing in disguise, because it will force you to get the fill and the drain plugs operational.

First of all, regardless of whether you are in 2wd or 4wd, transfer case components are turning whenever the vehicle is moving, so you need oil in there all the time.

Next, you should check the transfer case fluid level AND the level in the front and rear diffs at least at every oil change. So, if you are doing your own oil changes, then get the correct socket to fit the plugs. The fluid level needs to be right up to the bottom of the fill plug.... that is, you fill the case until fluid starts coming out the fill plug hole.

Finally, when you get the correct socket, drain the remaining fluid from the transfer case and refill it with fresh fluid. This is good preventive maintenance and should be done every 2 or 3 years anyways. Check your owners manual, but I think it uses automatic transmission fluid.