GMC Duramax Diesel 2015 Owner's Manual page 92

With a foot on the brake pedal,
move the shift lever through
each gear range, pausing for
about three seconds in each
range. Then, position the shift
lever in P (Park).
Let the engine run at idle for
three minutes or more.
Then, without shutting off the
engine, follow these steps:
The transmission dipstick is located
near the center of the engine
compartment and will be labeled
with the graphic shown.
See Engine Compartment Overview
on page 10-3 for location.
1. Flip the handle up and then pull
out the dipstick and wipe it with
a clean rag or paper towel.
2. Push it back in all the way, wait
three seconds, and then pull it
back out again.
Check both sides of the dipstick,
and read the lower level. The
fluid level must be in the COLD
area for a cold check or in the
HOT or cross-hatched area for a
hot check. Be sure to keep the
dipstick pointed down to get an
accurate reading.
3. If the fluid level is in the
acceptable range, push the
dipstick in all the way, then flip
the handle down to lock the
dipstick in place.
Vehicle Care
What Transmission Fluid
to Use
Cold Operation
When temperatures are very cold,
the transmission will prevent certain
operations to protect against
damage. The information below
shows shift range availability based
on transmission oil temperatures:
All shift ranges available at
25°C ( 13°F) or above.
2 (Second) and 3 (Third) shift
ranges only at 35°C ( 31°F) to
25°C ( 13°F).
2 (Second) shift range only at
35°C ( 31°F) or lower.
Torque converter clutch operation
will also be prevented when air or
transmission oil temperatures are
below certain levels.
Transmission shifting might be
firmer with a cold transmission. This
difference in shift quality is normal.
10-13