GMC CHEVROLET Silverado 6500HD 2019 Owner's Manual page 222

or meet ISO 22241.The fluid level in
the DEF tank must be maintained
for the vehicle to run properly. DEF
freezes when exposed to
temperatures below 11 °C (12 ° F).
For DEF tank capacity see
Capacities and Specifications 0 408.
It is normal to hear the DEF system
purge fluid back into the tank after
the vehicle is shut off.
Locating Diesel Exhaust Fluid
DEF can be purchased at your
dealer. It can also be purchased at
authorized vehicle and truck
dealerships. Additionally, some
diesel truck fueling stations or
retailers may have DEF for
purchase. For vehicles with an
active OnStar or connected service
plan, OnStar can help to locate a
DEF retailer. See Recommended
Fluids and Lubricants 0 398.
Filling the DEF Tank
Caution
Use only DEF that is GM
approved, or fluid containing the
API certified or ISO 22241 label.
The use of other fluids could
damage the system, requiring
costly repairs that will not be
covered by the vehicle warranty.
It is recommended to fill the DEF
tank on level ground and when the
vehicle is not running.
When adding fluid, it is
recommended to fill the DEF tank.
For DEF tank capacity see
Capacities and Specifications 0 408.
Caution
Do not overfill the DEF tank and
do not allow DEF to contact the
finished surfaces of the vehicle,
as it could damage the vehicle
(Continued)
Driving and Operating
Caution (Continued)
finish. If DEF is spilled during
filling, wipe any affected surface
with a damp cloth.
Do not overfill the DEF tank. When
fluid reaches the top of the fill pipe,
stop filling.
The def tank fill is on the rear of the
passenger-side front quarter fender.
The DEF cap is blue.
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