Whether a vehicle can safely continue to be driven depends on what is wrong with the transfer case. A minor leak is very different from severe grinding, binding, vibration or a transfer case that is no longer transferring power correctly.
Continuing to drive with a serious transfer case problem can potentially lead to additional drivetrain damage. Certified Transmission in Bellevue can inspect the system and determine how serious the problem is. If the vehicle is grinding, binding or behaving unpredictably, avoid unnecessary driving until it can be evaluated.