Your owners manual should have some of the gory details.... fluid should be Mercon in most cases but it doesn't share the transmission fluid. This is not to say that some years/models can't have one unit gaining fluid and the other losing fluid......BTW, this is rarely "good".
You'll find two 3/8ths square drive plugs on the T-case. Remove the sight plug (the upper one) first.... then remove the lower one and drain the fluid into a suitable container. Again, the owners manual would help with capacity, but expect 2.5 to 3 litres (one US quart is slightly less than a litre). There is a magnet inside the case visible when the drain plug is out...... expect some "hair" but also look for "chunks".
Ford recommends changing the transfer case fluid every 60,000 miles (normal or severe service schedule)
The following is for a 1996 Explorer 4 WD (NOT AWD) -
Manual Transmission and Transfer Case Fluid
Checking the Manual Transmission Fluid
Clean the filler plug on the side of the case. Remove the filler plug. The fluid level should be up to the bottom of the filler plug hole.
If additional fluid is required:
Add enough fluid through the filler plug hole to bring the level up to the bottom of the hole. Use only fluid certified to meet Ford Motor Company lubricant specification as listed under Refill Capacities, Motorcraft Parts, and Lubricant Specifications, later in this chapter.
Replace the filler plug in its original position, making sure it is fully seated.
Refill Capacities
4-Wheel Drive Transfer Case - 3.0 Pints (1.4 Liters)
Fluid Specifications
Transfer Case (4x4 Only) - Motorcraft Mercon Automatic Transmission Fluid - XT-2-QDX - Mercon
Reason for wanting to change the xfer case fluid is that I had been getting the blinking 4x4/2wd/4w Low lights, which usually indicates a faulty or dirty speed sensor. A couple months ago I removed both sensors (front and rear), and both had metal "hair" on them (due to the magnet molded into the Hall effect speed sensors). Cleaned the metal hair off and the 4x4 has been fine. Past week have noticed the blinking lights again.
My assumption is that more metal hair has accumulated on the sensors, OR that one of the sensors is actually faulty. To eliminate the metal hair theory, I was going to change the xfer case fluid, re-clean the sensors, and see where we go from there.
replying to Mike Mayer, Mike P wrote: Mike I also have an Explorer and the rear diff. Uses a 75W/90W on a standard axle and a 75W/140W on a all traction rear plus a traction modifier. Now the fluid I got was a Mobil 75W/140W with the modifier in there already, it cost $19.00 per bottle. The transfer case looks like Mercon III.......hope this helps.
MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.