From The Owners Manual:
ENGINE BLOCK HEATER — IF EQUIPPED
The engine block heater warms engine coolant and
permits quicker starts in cold weather. Connect the heater
cord to a ground-fault interrupter protected 110–115 Volt
AC electrical outlet with a grounded, three-wire extension
cord.
Its use is recommended for environments that routinely
fall below -10°F (-23°C). It should be used when the
vehicle has not been running for long periods of time and
should be plugged in two hours prior to start. Its use is
required for cold starts with temperatures under -20°F
(-28°C).
To ensure reliable starting at these temperatures, use of
an externally powered electric engine block heater (available
from your authorized dealer) is recommended.
66 STARTING AND OPERATING