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Transmission Fluids
Background & Properties
Important Transmission Fluid Properties
July 2017
Automatic Transmission Fluids (ATFs)
ATFs must be able to hold loads and encourage smooth shifts. Therefore, ATFs have a high dynamic coefficient of
friction with a moderate static coefficient of friction. ATFs do contain friction modifiers, which translate to moderate
static friction to avoid harsh shifts.
Automatic Transmission
Fluids
Sliding Speed Decreasing
Torque,
Nm
TES-389
TO-4 Fluids
The most dramatic friction characteristics are found in the TO-4 fluids for powershift transmissions. TO-4 fluids have
the highest static coefficient of friction for fast lock-up and outstanding holding capacity. The chart depicts this fact
with its sharp upward point illustrating a tight, firm lock-up.
Powershift Transmission
Fluids
Sliding Speed Decreasing
Torque,
Nm
TO-4
D 4