GMC 2012 Canyon Owner's Manual page 259

Refer to the Maintenance Schedule
to determine what kind of
transmission fluid to use.
See
Add fluid only after checking the
transmission fluid while it is hot.
A cold check is used only as a
reference. If the fluid level is low,
add only enough of the proper fluid
to bring the level up to the HOT area
for a hot check. It does not take
much fluid, generally less than
0.5 L (1 pt). Do not overfill.
After adding fluid, recheck the
fluid level as described under
How to Check Automatic
Transmission Fluid, earlier in
this section.
When the correct fluid level is
obtained, push the dipstick back
.
in all the way; then flip the
handle down to lock the dipstick
in place.
A good time to check the manual
transmission fluid is when the
engine oil is changed. However, the
fluid in the manual transmission
does not require changing.
Because this operation can be a
little difficult, it may be decided to
have this done at the dealer service
department.
If not taken to the dealer, be sure to
follow all the instructions here, or a
false reading on the dipstick could
result.