2012 Chevrolet Tahoe Owner's Manual - Page 392

10-20 Vehicle Care 5. 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. Notice: If the pressure cap is not tightly installed, coolant loss and possible engine damage may occur. Be sure the cap is properly and tightly secured. 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 upper radiator hose can be felt getting hot. Watch out for the engine cooling fan. 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.