Chevrolet 2003 Silverado 1500 Pickup Owner's Manual page 330

Put on extra clothing or wrap a blanket around you. If
you have no blankets or extra clothing, make body
insulators from newspapers, burlap bags, rags, floor
mats
-
anything you can wrap around yourself or
tuck tinder your clothing to keep warm.
Snow can trap exhaust gases under ysur
vehicle. This can cause deadly CO (carbon
monoxide) gas to get inside. CO could
overcome you and kill you. You can't see it or
smell it, so you might not know it is in your
vehicle. Clear away snow from around the
base of your vehicle, especially any that is
blocking your exhaust pipe. And check around
again from time to time to be sure snow
doesn't collect there.
Open a window just a little on the side of the
vehicle that's away from the wind. This will
help keep CO out.
Run your engine only as long as you must. This saves
fuel. When you run the engine, make it go a little faster
than just idle. That is, push the accelerator slightly. This
uses less fuel for the heat that you get and it keeps the
battery charged. You will need a well-charged battery to
restart the vehicle, and possibly for signaling later on with
your headlamps. Let the heater run for a while.
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