GMC Duramax Diesel 2015 Owner's Manual page 41

9-14 Driving and Operating
Locating Diesel Exhaust Fluid
DEF can be purchased at a
Chevrolet or GMC 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
subscription, OnStar can help to
locate a DEF retailer. See
Customer Assistance Offices in
the owner manual for phone
numbers to assist in contacting a
GM dealer. See Recommended
Fluids and Lubricants on page 11-8.
Filling the DEF Tank
Caution
Use only exhaust fluid 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.
When adding DEF to an empty or
very low tank, always add at least
7.6 L (2 gal) of fluid to release the
vehicle from speed limitation.
Do not overfill the DEF tank. When
fluid reaches the top of the fill pipe,
stop filling. Do not top off the DEF
tank. When the EXHAUST FLUID
RANGE XXXX KM (MI) message in
the Driver Information Center (DIC)
displays at approximately 1 600 km
(1,000 mi) of fluid range remaining,
about 11 L (3 gal) of DEF have
been used.
If you spill DEF on the vehicle while
filling the tank, rinse the area with
water and wipe the surface with a
damp cloth.
DEF Fill - Vans
For vans, the DEF fill is behind the
fuel fill door. The DEF cap is blue,
and the diesel cap is green.
The fill tube location for chassis-cab
and cutaway vans finished by an
upfitter will vary. Check the upfitter
manual.