TRANSFER CASE LUBRICANT
Transfer cases provide high-and low-drive range selection for 4WD vehicles.
They are sealed units that have gears, bearings, and shafts that house their own
lubricant (much like manual transmissions and differentials). They must be
inspected and maintained. Fluid level, color, consistency, and smell are critical
when inspecting transfer cases. They use one of three fluid types: gear oil,
automatic transmission fluid, or special synthetic lube designed specifically for
transfer cases. Your owner’s manual will define exactly what type of lubricant is
used.
Color
When inspecting transfer case fluid, healthy fluid is red (automatic transmission
fluid), clear, blue, green, or red (synthetic lube), or black (gear oil). Look closely
for the presence of metal flakes, which indicate internal wear. If metal flakes are
present, open the unit and inspect for wear before putting it back into service.
Left to operate with wear, the transfer case will eventually fail. A milky color
indicates moisture contamination. In such a case, the lube must be replaced
immediately or heat and friction will buildup and the transfer case will fail.
Consistency
Transfer case lubricants should be smooth and slippery to the touch. Grit
indicates the presence of either dirt or wear material. If this is the case, further
inspection is warranted to prevent premature failure.
Smell
A burnt smell indicates internal overheating caused by friction and lack of
lubrication. Open the unit and inspect for bearing, gear, or shaft wear or failure
as well as leaks.