GMC Duramax Diesel 2015 Owner's Manual page 100

Warning (Continued)
surge tank pressure cap
little when the engine and
radiator are hot.
The vehicle must be on a level
surface. When the engine is cold,
the coolant level should be at the
COLD FILL mark.
Adding Coolant (Pickup and Van
Models)
Caution
If coolant is changed or added,
always add enough to fill the
system completely or engine
damage may occur.
If more coolant is needed, add the
proper DEX-COOL coolant mixture
at the surge tank, but be careful not
to spill it.
even a 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.
This vehicle has a specific
coolant fill procedure. Failure to
follow this procedure could cause
the engine to overheat and be
severely damaged.
Steam and scalding liquids from a
hot cooling system can blow out
and burn you badly. They are
Warning
Caution
Warning
(Continued)
Vehicle Care
Warning (Continued)
under pressure, and if you turn
the coolant surge tank pressure
cap even a little they can
come out at high speed. Never
turn the cap when the cooling
system, including the coolant
surge tank pressure cap, is hot.
Wait for the cooling system and
coolant surge tank pressure cap
to cool if you ever have to turn
the pressure cap.
If no coolant is visible in the surge
tank, add coolant as follows:
10-21