Chevrolet 2008 Silverado 1500 Pickup Owner's Manual page 445

3. Fill the coolant surge tank with the proper mixture,
to the FULL COLD mark.
4. With the coolant surge tank pressure cap off, start
the engine and let it run until the engine coolant
temperature gage indicates approximately
195°F (90°C).
By this time, the coolant level inside the coolant
surge tank may be lower. If the level is lower, add
more of the proper mixture to the coolant surge tank
until the level reaches the FULL COLD mark.
5. Then replace the pressure cap. Be sure the
pressure cap is hand-tight and fully seated.
6. Verify coolant level after engine is shut off and the
coolant is cold. If necessary, repeat coolant fill
procedure Steps 1 through 6.
5-39