Buick 2007 LaCrosse Owner's Manual page 334

Driving On Grades
Reduce speed and shift to a lower gear before
starting down a long hill or steep downgrade. If the
vehicle is not shifted down, the brakes might
have to be used so much that they would get hot
and no longer work well.
On a long uphill grade, shift down and reduce the
vehicle's speed to around 45 mph (70 km/h) to
reduce the possibility of engine and transaxle
overheating.
If towing a trailer, you may want to drive in
THIRD (3) instead of DRIVE (D). Shift to a lower
gear as needed.
334
Parking on Hills
CAUTION:
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You really should not park your vehicle,
with a trailer attached, on a hill. If
something goes wrong, your rig could
start to move. People can be injured, and
both your vehicle and the trailer can be
damaged.
But if the rig ever has to be parked on a hill, here
is how to do it:
1. Apply the regular brakes, but do not shift into
PARK (P) yet.
2. Have someone place chocks under the
trailer's wheels.
3. When the wheel chocks are in place, release
the regular brakes until the chocks absorb
the load.
4. Reapply the regular brakes. Then apply the
parking brake, and shift to PARK (P).
5. Release the regular brakes.