Buick 2007 Rainier Owner's Manual page 376

Wait at least 30 minutes before checking the
transmission fluid level if you have been driving:
•
When outside temperatures are above
90°F (32°C).
•
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 180°F to
200°F (82°C to 93°C).
Get the vehicle warmed up by driving about
15 miles (24 km) when outside temperatures are
above 50°F (10°C). If it is colder than 50°F (10°C),
drive the vehicle in THIRD (3) until the engine
temperature gage 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 50°F (10°C) or more. If it
is colder than 50°F (10°C), you may have to idle
the engine longer.
376
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.
Checking the Fluid Level
Prepare your vehicle as follows:
1. Park your vehicle on a level place. Keep the
engine running.
2. With the parking brake applied, place the shift
lever in PARK (P).
3. With your 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 PARK (P).
4. Let the engine run at idle for three minutes
or more.