Ford 2009 Flex Owner's Manual page 278

Driving
All components of the AWD system are sealed for life and require no
maintenance.
If your vehicle is equipped with AWD, a spare tire of a different size
other than the tire provided should never be used. If the spare tire is
installed, the AWD system may disable automatically and enter front
wheel drive only mode to protect driveline components. This condition
may be indicated by an AWD OFF message in the message center (see
Message center section in the Driver Controls chapter for more
information). If there is an AWD OFF message in the message center
from using the spare tire, this indicator should turn off after reinstalling
the repaired or replaced normal road tire and driving a short distance. It
is recommended to reinstall the repaired or replaced road tire as soon as
possible. Major dissimilar tire sizes between the front and rear axles
could cause the AWD system to stop functioning and default to front
wheel drive or damage the AWD system.
Note: Your AWD vehicle is not intended for off-road use. The AWD
feature gives your vehicle some limited off-road capabilities in which
driving surfaces are relatively level, obstruction-free and otherwise
similar to normal on-road driving conditions. Operating your vehicle
under other than those conditions could subject the vehicle to excessive
stress which might result in damage which is not covered under your
warranty.
Driving on slippery surfaces with AWD vehicles
AWD vehicles are specially equipped for driving on sand, snow, mud and
rough roads and have operating characteristics that are somewhat
different from conventional vehicles, both on and off the highway.
When driving at slow speeds off-highway under high outside
temperatures, use a low gear when possible. A lower gear operation will
maximize the engine and transmission cooling capability.
Under severe operating conditions, the A/C may cycle on and off to
protect overheating of the engine.
Basic operating principles
• Drive slower in strong crosswinds which can affect the normal steering
characteristics of your vehicle.
• Be extremely careful when driving on pavement made slippery by
loose sand, water, gravel, snow or ice.
278
2009 Flex (471)
Owners Guide, 2nd Printing
USA (fus)