Oldsmobile 1995 88 Owner's Manual page 325

Parking Brake and Automatic Transaxle PARK (P)
Mechanism Check
Park on a fairly steep hill, with the vehicle facing
downhill. Keeping your foot on the regular brake, set the
parking brake.
To check the parking brake: With the engine running
and transaxle in NEUTRAL (N), slowly remove foot
pressure from the regular brake pedal. Do this until
the vehicle is held by the parking brake only.
To check the PARK (P) mechanism's holding ability:
Shift to PARK (P). Then release all brakes.
Underbody Flushing
At least every spring, use plain water to flush any
corrosive materials from the underbody. Take care to
clean thoroughly any areas where mud and other debris
can collect.
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