Buick Verano Owner's Manual page 266

Never dispose of engine coolant by
putting it in the trash, pouring it on
the ground, or into sewers, streams,
or bodies of water. Have the coolant
changed by an authorized service
center, familiar with legal
requirements regarding used
coolant disposal. This will help
protect the environment and your
health.
The vehicle must be on a level
surface when checking the coolant
level.
Check to see if coolant is visible in
the coolant surge tank. If the coolant
inside the coolant surge tank is
boiling, do not do anything else until
it cools down. If coolant is visible
but the coolant level is not at the
indicated mark, add a 50/50 mixture
of clean, drinkable water and
DEX-COOL coolant at the coolant
surge tank, but be sure the cooling
system is cool before this is done.
See
for more information.
The coolant surge tank is located in
the engine compartment on the
driver side of the vehicle. See
for more information on
location.
If no problem is found, check to
see if coolant is visible in the
coolant surge tank. If coolant is
visible but the coolant level is not
at the indicated level mark, add a
50/50 mixture of clean, drinkable
water and DEX-COOL coolant at the
coolant surge tank, but be sure the
cooling system, including the
coolant surge tank pressure cap,
is cool before you do it.
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 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.