Pontiac 2008 G6 - Manual (Page 235)

Driving On Grades
When towing a trailer on long uphill grades and the
outside temperature is above 85°F (29°C), reduce your
vehicle speed to 45 mph (72 km/h) to avoid overheating
the engine cooling system.
Reduce speed and shift to a lower gear before you start
down a long or steep downgrade. If you do not shift
down, you might have to use your brakes so much that
they would get hot and no longer work well.
Parking on Hills
{ CAUTION:
You really should not park your vehicle, with a
trailer attached, on a hill. If something goes
wrong, your rig could start to move. People
can be injured, and both your vehicle and the
trailer can be damaged.
But if you ever have to park your rig on a hill, here is
how to do it:
1. Apply your regular brakes, but do not shift into
PARK (P) for an automatic transmission or into
gear for a manual transmission. When parking
uphill, turn your wheels away from the curb. When
parking downhill, turn your wheels into the curb.
2. Have someone place chocks under the trailer
wheels.
3. When the chocks are in place, release the regular
brakes until the chocks absorb the load.
4. Reapply the regular brakes. Then apply your
parking brake and shift into PARK (P).
5. Release the regular brakes.
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