the transfer case (4 x 4 box) probalby had MERCON in it as did the transmission from the factory. YOu probably will get MERCON V now, that is the upgrade.. There is no friction modifier. IF you doing the front or rear differential, you use a gear lube. 80-90 wt was the original. New trucks use 75 w140 in the rear end. If you have a limit slip clutch in the rear, you can add friction modifier to the differential gear lube. You can look at the operators manual here... they will list oil and quantities.
Just got a 1996 explorer. I'm wanting to change transfer case fluid what type of of fluid works best? I also assume a friction modifier additive is used as well?
" the transfer case is a Borg-Warner make. It is the same case GMC used in the S15 Typhoon hot-rod. Usage indicates exceptional reliability. The AWD does not have a center disconnect as does a 4WD. The AWD is a single-speed transfer case. Therefore, the AWD does not have a low range like 4WD. Under severe off-road conditions, the AWD would not perform like the 4WD low range.
....the AWD functions like this: the transfer case has no driver input; i.e., no switch. Thirty-five percent of the torque is distributed to the front axle; sixty-five percent to the rear axle at all times. When wheel slippage occurs, the viscous clutch in the transfer case transfers more torque to the axle that has the most traction.....35% torque to the front/ 65% to the rear is a measurement under normal conditions. If the front end was affected by icy road conditions, where the transfer case clutch transferred the maximum torque to the front axle, the ratio could be 50/50 or even 65% (front) and 35% (rear). According to Ford Engineering personnel, AWD testing in off-road dirt/ sand conditions, the AWD performed superbly."
The viscous clutch is a torque distribution device. It is non-repairable. The internal construction of the viscous clutch consists of alternating plates that are connected to the front and rear outputs of the transfer case. The viscous clutch is filled with a high viscosity fluid which flows through slots in the plates. The resistance to shear causes the plates to transmit torque at the needed ratio.