GMC 2015 Sierra Denali Owner's Manual page 291

10-20 Vehicle Care
5.3L V8 Engine Shown, 6.2L
V8 Engine Similar
6.0L V8 Engine
The coolant level should be at or
above the FULL COLD mark. If it is
not, there may be a leak in the
cooling system.
How to Add Coolant to the
Coolant Surge Tank
If the vehicle has a diesel engine,
see Cooling System in the
Duramax diesel supplement for the
proper coolant fill procedure.
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.
Caution
This vehicle has a specific
coolant fill procedure. Failure to
follow this procedure could cause
the engine to overheat and be
severely damaged.
Warning
Steam and scalding liquids from a
hot cooling system can blow out
and burn you badly. 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 no coolant is visible in the surge
tank, add coolant.