Caution: The radiator cap should be removed from a cool engine only. If the radiator cap is removed from a hot cooling system, serious personal injury may result.

Caution: As long as there is pressure in the cooling system, the temperature can be considerably higher than the boiling temperature of the solution in the radiator, without causing the solution to boil. Removal of the radiator cap while the engine is hot and the pressure is high will cause the solution to boil instantaneously and possibly with explosive force, spewing the solution over the engine, fenders, and person removing the cap. Under some conditions, the engine coolant is combustible.

Use the following procedure in order to drain the cooling system:

1. Place a drain pan under the radiator drain cock.
2. Install a tube on the drain cock.
3. Place the end of the tube in the drain pan.
4. Ensure that the cooling system is cool. Remove the radiator cap.
5. Open the drain cock completely.
6. Allow the cooling system to drain until the flow stops.
7. Place a drain pan under the engine.
8. Remove the drain plug from the engine block.
9. Allow the engine block to drain until the flow stops. There may be some more drainage from the radiator at this time.
10. Replace the engine block drain plug.
11. Close the radiator drain cock.

Notice: When adding coolant, it is important that you use GM Goodwrench DEX-COOL™ coolant. If coolant other than DEX-COOL™ is added to the system, the engine coolant will require change sooner: at 50 000 km (30,000 miles) or 24 months.

Use the following procedure in order to refill the cooling system:

1. Inspect the radiator drain cock in order to ensure that the drain cock is closed.
2. Inspect the engine drain plug in order to ensure that the drain plug is closed.
3. Place a large funnel in the radiator fill hole.
4. Fill the system with ethylene glycol based (DEX-COOL™) to the radiator. Do not pre-mix the coolant and water. Fill the remainder of the radiator with clean drinkable water in order to equal a 50/50 mix. Refer to Engine Cooling System Specifications for the cooling system capacity. The filling may be slowed due to the thermostat being closed.
5. Fill the cooling system to 13 mm (½ in) below the fill line.
6. Start the engine and allow the cooling system to warm up. When the thermostat opens, the coolant level may drop. If the level drops, add coolant until the level is up to the top.
7. Replace the radiator cap.
8. Inspect the coolant level in the recovery reservoir or the radiator surge tank. Add coolant as needed.