GMC Duramax Diesel 2015 Owner's Manual page 91

10-12 Vehicle Care
When to Check and Change
(Van Models)
Change the fluid and filter at the
intervals listed. See Maintenance
Schedule on page 11-3.
Use the transmission fluid listed in
Recommended Fluids and
Lubricants on page 11-8.
How to Check
Because this operation can be a
little difficult, the decision may be
made to have this done at the
dealership service department.
If the decision is made to perform
this operation, be sure to follow all
the instructions here, or a false
reading on the dipstick could result.
Caution
Too much or too little fluid can
damage the transmission. Too
much can mean that some of the
fluid could come out and fall on
Caution (Continued)
hot engine parts or exhaust
system parts, starting a fire. Too
little fluid could cause the
transmission to overheat. Be sure
to get an accurate reading if
checking the transmission fluid.
Wait at least 30 minutes before
checking the transmission fluid level
if the vehicle has been driven:
When outside temperatures are
above 32°C (90°F).
At high speed for quite a while.
In heavy traffic
hot weather.
While pulling a trailer.
To get the right reading, the fluid
should be at normal operating
temperature, which is 82°C to 93°C
(180°F to 200°F). Get the vehicle
warmed up by driving about 24 km
(15 mi) when outside temperatures
(Continued)
are above 10°C (50°F). If it is colder
than 10°C (50°F), drive the vehicle
until the engine temperature gauge
moves and then remains steady for
10 minutes.
A cold check can be made after the
vehicle has been sitting for eight
hours or more with the engine off,
but this is used only as a reference.
Let the engine run at idle for
five minutes if outside temperatures
are 10°C (50°F) or more. If it is
colder than 10°C (50°F), the engine
may have to idle longer. Should the
fluid level be low during this cold
check, the fluid must be checked
when hot before adding fluid.
Checking the fluid hot will give you
a more accurate reading of the fluid
especially in
level.
Checking the Fluid Level
Prepare the vehicle as follows:
Park the vehicle on a level
place. Keep the engine running.
With the parking brake applied,
place the shift lever in P (Park).