GMC 1994 Yukon Owner's Manual page 190

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Keep your vehicle in good shape. Check all fluid
levels
and also the
brakes, tires, cooling system and transmission. These parts can work
hard on mountain roads.
Know how to go down hills. The most important thing to know is this:
let your engine do some of the slowing down. Shift to a lower gear
when you go down a steep or long hill.
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Know how to go uphill. You may want to shift down to a lower gear.
The lower gears help cool your engine and transmission, and you can
climb the hill better.
Stay in your own lane when driving on two-lane roads in hills
or
mountains. Don't swing wide or cut across the center of the road. Drive
at speeds that let you stay in your own lane.
As you go over the top of a hill, be alert. There could be something in
your lane, like a stalled car or an accident.
You may see highway signs on mountains that warn of special
problems. Examples are long grades, passing or no-passing zones, a
falling rocks area, or winding roads. Be alert to these and take
appropriate action.
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