Buick 1998 Century Owner's Manual page 235

Engine Overheating
You will find a coolant temperature gage and a hot
engine warning light on your instrument panel. See
"Engine Coolant Temperature Gage" and "Engine
Coolant Temperature Warning Light" in the Index.
You also have a low coolant warning light on your
instrument panel. See "Low Coolant Light" in the Index.
Overheated Engine Protection
Operating Mode
Should an overheated engine condition exist, an
overheat protection mode which alternates firing groups
of three cylinders helps prevent engine damage. In this
mode, you will notice a significant loss in power and
engine performance. The low coolant light may come on
and the temperature gage will indicate an overheat
condition exists. This emergency operating mode allows
your vehicle to be driven to a safe place in an
emergency. Towing a trailer in the overheat protection
mode should be avoided.
NOTICE:
After driving in the overheated engine protection
operating mode, to avoid engine damage, allow
the engine to cool before attempting any repair.
The engine oil will be severely degraded. Repair
the cause of coolant loss and change the oil. See
"Engine Oil, When to Change" in the Index.
5-15