How To Check Automatic Transmission Fluid - GMC 2010 Sierra Owner's Manual

How to Check Automatic Transmission
Fluid
Because this operation can be a little difficult, you may
choose to have this done at the dealer service
department.
If you do it yourself, be sure to follow all the instructions
here or you could get a false reading on the dipstick.
Notice: 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 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 you have been driving:
When outside temperatures are above
32°C (90°F).
At high speed for quite a while.
In heavy traffic especially in 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 miles) when outside temperatures are above 10°C
(50°F). If it is colder than 10°C (50°F), drive the vehicle
in 3 (Third) until the engine temperature gauge moves
and then remains steady for 10 minutes.
A cold fluid 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), you may
have to idle the engine longer. Should the fluid level be
low during this cold check, you must check the fluid hot
before adding fluid. Checking the fluid hot will give you
a more accurate reading of the fluid level.
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