GMC C-Series 2001 Owner's Manual page 188

Sloped Hood
When the engine is cold, the coolant level should be
above the HOT LEVEL mark on the vehicle with the
specialty hood, or at or above the COLD LEVEL mark
on the vehicle with the sloped hood. If it isn't, you may
have a leak in the radiator hoses, heater hoses, radiator,
water pump or somewhere else in the cooling system.
CAUTION:
Heater and radiator hoses, and other engine
parts, can be very hot. Don't touch them. If you
do, you can be burned.
Don't run the engine if there is a leak. If you run
the engine, it could lose all coolant. That could
cause an engine fire, and you could be burned.
Get any leak fixed before you drive the vehicle.
NOTICE:
Engine damage from running your engine
without coolant isn't covered by your warranty.
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