Ford Mustang Owner's Manual page 307

Maintenance and Specifications
BRAKE/CLUTCH FLUID
Brake and clutch (if equipped) systems are supplied from the same
reservoir.
The fluid level will drop slowly as
the brakes wear, and will rise when
the brake components are replaced.
Fluid levels between the MIN and
MAX lines are within the normal
operating range; there is no need to
add fluid. If the fluid levels are
outside of the normal operating
range, the performance of the
system could be compromised; seek
service from your authorized dealer
immediately.
TRANSMISSION FLUID
Checking automatic transmission fluid
The automatic transmission does not have an underhood transmission
fluid dipstick.
Refer to your scheduled maintenance information for scheduled
intervals for fluid checks and changes. Your transmission does not
consume fluid. However, the fluid level should be checked if the
transmission is not working properly, (i.e., if the transmission slips or
shifts slowly) or if you notice some sign of fluid leakage.
Transmission fluid should be checked and, if required, added by
an authorized dealer.
Do not use supplemental transmission fluid additives, treatments or
cleaning agents. The use of these materials may affect transmission
operation and result in damage to internal transmission components.
307
2012 05+ Mustang (197)
Owners Guide, 3rd Printing
USA (fus)