Chevrolet 2012 Volt Owner's Manual page 302

10-18 Vehicle Care
The coolant level should be at or
above the cold fill line on the
coolant surge tank. If it is not, there
could be a leak in the cooling
system.
How to Add Coolant to the
Coolant Surge Tank
WARNING
You can be burned if you spill
coolant on hot engine parts.
Coolant contains ethylene glycol
and it will burn if the engine parts
are hot enough. Do not spill
coolant on a hot engine.
Notice: This vehicle has a
specific coolant fill procedure.
Failure to follow this procedure
could cause the engine to
overheat and be severely
damaged.
WARNING
The electric fans under the hood
can start up even when the
engine is not running and can
cause injury. Keep hands,
clothing, and tools away from any
underhood electric fan.
WARNING
Steam and scalding liquids from a
hot cooling system can blow out
and burn you badly. They are
under pressure, and if you turn
the surge tank pressure
cap even a little they can
come out at high speed. Never
turn the cap when the cooling
system, including the surge tank
pressure cap, is hot. Wait for the
cooling system and surge tank
pressure cap to cool if you ever
have to turn the pressure cap.
I n f o r ma t i o n P r o v i d e d b y :
If coolant is needed, add the proper
DEX-COOL coolant mixture at the
coolant surge tank.
The coolant surge tank pressure
cap can be removed when the
cooling system, including the surge
tank pressure cap and upper
radiator hose, is no longer hot.
1. Turn the pressure cap slowly
counterclockwise. If a hiss is
heard, wait for that to stop.
A hiss means there is still some
pressure left.
2. Keep turning the cap and
remove it.