Automatic Transmission - GMC 1994 Sonoma Owner's Manual

How long should you keep the coolant heater plugged in? The answer
depends on the weather, the kind of oil you have, and some other things.
Instead of trying to list everything here, we ask that you contact a GM
dealer in the area where you'll be parking your vehicle. The dealer can give
you the best advice for that particular area.
Automatic Transmission
There are several
different positions for
your shift lever.
P (Park)
This locks your rear wheels. It's the best position to use when you start
your engine because your vehicle can't move easily.