Buick Lucerne 2007 Owner's Manual page 120

REVERSE (R): Use this gear to back up.
Notice: Shifting to REVERSE (R) while your
vehicle is moving forward could damage
the transaxle. The repairs would not be
covered by your warranty. Shift to
REVERSE (R) only after your vehicle
is stopped.
To rock your vehicle back and forth to get out
of snow, ice, or sand without damaging your
transaxle, see If Your Vehicle is Stuck in Sand,
Mud, Ice, or Snow on page 306.
NEUTRAL (N): In this position, your engine does
not connect with the wheels. To restart when
you are already moving, use NEUTRAL (N) only.
Also, use NEUTRAL (N) when your vehicle is
being towed.
120
CAUTION:
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Shifting into a drive gear while your
engine is running at high speed is
dangerous. Unless your foot is firmly on
the brake pedal, your vehicle could move
very rapidly. You could lose control and
hit people or objects. Do not shift into a
drive gear while your engine is running at
high speed.
Notice: Shifting out of PARK (P) or
NEUTRAL (N) while the engine is running at
high speed may damage the transaxle. The
repairs would not be covered by your warranty.
Be sure the engine is not running at high
speeds when shifting your vehicle.