Oldsmobile 2004 Alero Owner's Manual page 88

Engine Coolant Heater
2.2L L4 ECOTEC™ Engine
2-20
3400 V6 Engine
Your vehicle may have this feature. In very cold
weather, 0°C ( 18°F) or colder, the engine coolant
heater can provide 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. At temperatures
above 32°F (0°C), use of the coolant heater is not
required.