BW1356 Transfer Case Service

How to Change Fluid in the BorgWarner BW1356 Transfer Case

The Borg Warner BW1356 is a heavy duty, chain driven transfer case that was used in 1987 to 1997 Ford F-Series pickups and the full-size Ford Bronco. Available in both manual and electric shift versions, the transfer case fluid should be replaced every 60,000 miles or anytime the transfer case is submerged in water. Ford specifies the use of synthetic MERCON ATF, not a heavy gear oil. The BW1356 has an internal pump that keeps the bearings lubricated - the pump is not compatible with thicker oils. Draining and replacing the fluid regularly prolongs the life of the transfer case and keeps 4WD engagement smooth and positive.

Applicable Model Years: 1987 to 1997 Ford F-Series
BW1356 Fluid Spec: MERCON synthetic ATF
BW1356 Fluid Capacity: 2 quarts

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BW1356 drain and fill plug locations

• The drain and fill plugs are both located on the back of the transfer case. The drain plug (lower of the two) is towards the driver side while the fill plug is located toward the passenger side (looking at the rear of the case). Both require a 3/8" square drive (socket wrench of small breaker bar) for removal/installation.

BW1356 fluid draining

• Place an oil catch can below the drain plug.

• Remove the fill plug first! If you remove the drain plug first only to find out later that the fill plug is stuck and/or stripped, you've got a much bigger project on your hands. If the fill plug comes out without trouble, then remove the drain plug and drain the transfer case completely.

Refilling the BW1356 transfer case

• Once the fluid has drained completely, reinstall the drain plug after cleaning it and applying a couple of wraps of oil resistant Teflon tape.

• Use a fluid pump to pump fluid into the transfer case through the fill hole until fluid begins to run out (the fill hole also acts as the fill line). Once the transfer case is full, replace the fill plug after cleaning it and applying a couple wraps of oil resistant Teflon tape.

• The actual fluid capacity of the BW1356 is spec'd at 2 quarts. Ford calls for MERCON synthetic ATF - do not use anything other than synthetic ATF in this transfer case.