Buick LaCrosse Owner's Manual page 352

Vehicles with all-wheel drive cannot
be dolly towed.
The vehicle cannot be dolly towed
from the rear.
Locks are lubricated at the factory.
Use a de-icing agent only when
absolutely necessary, and have the
locks greased after using. See
Recommended Fluids and
Lubricants.
To preserve the vehicle's finish,
wash it often and out of direct
sunlight.