Chevrolet 2010 Impala Owner's Manual page 132

Downshifting the transmission in slippery road conditions
could result in skidding, see "Skidding" under Loss of
Control on page 5-11.
Notice: Driving the vehicle if you notice that it is
moving slowly or not shifting gears as you increase
speed may damage the transmission. Have the
vehicle serviced right away. You can drive in
2 (Second) when you are driving less than 35 mph
(55 km/h) and D (Drive) for higher speeds until then.
3 (Third): This position is also used for normal
driving. However, it reduces vehicle speed more than
D (Drive) without using the brakes. You might choose
3 (Third) instead of D (Drive) when driving on hilly,
winding roads, when towing a trailer, so there is less
shifting between gears and when going down a
steep hill.
2 (Second): This position reduces vehicle speed even
more than 3 (Third) without using the brakes. You can
use 2 (Second) on hills. It can help control vehicle speed
as you go down steep mountain roads. You would also
want to use the brakes off and on.
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Notice: Driving in 2 (Second) for more than 25 miles
(40 km) or at speeds over 55 mph (90 km/h) may
damage the transmission. Also, shifting into
2 (Second) at speeds above 65 mph (105 km/h)
can cause damage. Drive in 3 (Third) or D (Drive)
instead of 2 (Second).
1 (First): This position reduces vehicle speed even
more than 2 (Second) without using the brakes. You
can use it on very steep hills, or in deep snow or mud.
If the shift lever is in 1 (First) while the vehicle is
moving forward, the transmission will not shift into first
gear until the vehicle is going slowly enough.
Notice: Spinning the tires or holding the vehicle
in one place on a hill using only the accelerator
pedal may damage the transmission. The repair
will not be covered by the vehicle warranty. If you
are stuck, do not spin the tires. When stopping on
a hill, use the brakes to hold the vehicle in place.