FORD 2015 F-150 - Manual (Page 192)

Maintenance and Modifications
The suspension and steering systems on
your vehicle have been designed and
tested to provide predictable performance
whether loaded or empty. For this reason,
we strongly recommend that you do not
make modifications such as adding or
removing parts (for example, lift kits or
stabilizer bars) or by using replacement
parts not equivalent to the original factory
equipment.
We recommend that you use caution when
your vehicle has either a high load or device
(such as ladders or luggage racks). Any
modifications to your vehicle that raise the
center of gravity may cause your vehicle
to roll over when there is a loss of vehicle
control.
Failure to maintain your vehicle correctly
may void the warranty, increase your repair
cost, reduce vehicle performance and
operational capabilities and adversely
affect you and your passenger's safety. We
recommend you frequently inspect your
vehicle's chassis components when your
vehicle is subject to off road usage.
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F-150 (), enUSA, First Printing
Four-Wheel Drive
(If Equipped)