Oldsmobile ALERO 2001 Owner's Manual page 94

Engine Coolant Heater (Option)
3400 V6 Engine
In very cold weather, 0 _ F ( 18 _ C) or colder, the engine
-
2.4L L4 Engine
coolant heater can help. You'll get easier starting and
-
better fuel economy during engine warm up. Usually,
the coolant heater should be plugged in a minimum of
four hours prior to starting your vehicle.
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