Buick 1998 Century Owner's Manual page 230

A vehicle can fa rom a car carrier if it isn't
adequately secured. This can cause a collision,
serious personal injury and vehicle damage. The
vehicle should be tightly secured with chains or
steel cables before it is transported.
Don't use substitutes (ropes, leather straps,
canvas webbing, etc.) that can be cut by sharp
edges underneath the towed vehicle. Always use
T-hooks inserted in the T-hook slots. Never use
J-hooks. They will damage drivetrain and
suspension components.
When your vehicle is being towed, have the ignition key
in OFF. The steering wheel should be clamped in a
straight-ahead position, with a clamping device
designed for towing service. Do not use the vehicle's
steering column lock for this. The transaxle should be in
NEUTRAL (N) and the parking
brake released.
NOTICE:
Don't have your vehicle towed on the drive
wheels, unless you must. If the vehicle must be
towed on the drive wheels, do not tow the vehicle
more than 500 cumulative miles (800 km) or
exceed 50 mph (80 km/h). Cumulative miles are
defined as total miles over the life of the vehicle.
For example, your vehicle cannot be towed
500 miles (800 km) each day of a trip totaling
3,000
miles
(4800 km). If these limitations must
be exceeded, then the drive wheels have to be
supported on a dolly.
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