MANUAL TRANSMISSION LUBRICANT
Manual transmissions are sealed units that have gears, shafts, bearings, bushings,
blocker rings, and synchronizer rings that house their own lubricant. They are
less touchy than automatics, but they still must be inspected and maintained
according to the manufacturer’s specs. Fluid level, color, consistency, and smell
are critical when inspecting manual transmissions. Manual transmissions use one
of three fluid types: motor oil, automatic transmission fluid, or gear oil. Your
owner’s manual will outline exactly what type of lubricant is used.
Color
When inspecting manual transmission fluid, it should appear red if it’s automatic
transmission fluid, caramel if it’s motor oil, or black if it’s gear oil. It’s important
to look closely for metal flakes in the fluid. Metal flakes indicate that there is
internal wear in the transmission. If this is the case, open the unit and inspect for
wear before putting the transmission back into service. If you run a transmission
that exhibits wear, it will fail in short order. A milky color indicates moisture
contamination. In this case, replace the gear lube immediately or else heat and
friction will buildup and the transmission will fail.
Consistency
Transmission fluid should be smooth and slippery to the touch. Grit indicates the
presence of either dirt or wear material. Further inspection is warranted to
prevent premature transmission failure.
Smell
A burnt smell indicates internal overheating due to friction or lack of lubrication.
The unit should be opened up and inspected for bearing or gear wear or failure
as well as for leaks.