Hummer H2 2009 Owner's Manual page 380

5. Safe operating level is within the HOT cross hatch
band on the dipstick. If the fluid level is not within the
HOT band, and the transmission temperature is
between 160°F and 200°F (71°C and 93°C), add or
drain fluid as necessary to bring the level into the
HOT band. If the fluid level is low, add only enough
fluid to bring the level into the HOT band. It does not
take much fluid, generally less than one pint (0.5L).
Do not overfill.
6. If the fluid level is in the acceptable range, push the
dipstick back in all the way, then flip the handle
down to lock the dipstick in place.
5-26
Consistency of Readings
Always check the fluid level at least twice using the
procedures described. Consistency is important to
maintaining proper fluid level. If fluid is added, it may take
15 minutes or longer to obtain an accurate reading
because of residual fluid draining down the dipstick tube.
If inconsistent readings persist, check the transmission
breather to be sure it is clean and not clogged. If readings
are still inconsistent, contact your dealer/retailer.