Caution: With a pressurized cooling system, the coolant temperature in the radiator can be considerably higher than the boiling point of the solution at atmospheric pressure. Removal of the surge tank cap, while the cooling system is hot and under high pressure, causes the solution to boil instantaneously with explosive force. This will cause the solution to spew out over the engine, the fenders, and the person removing the cap. Serious bodily injury may result.

Notice: When adding coolant, use DEX-COOL® coolant. If silicated coolant is added to the system, premature engine, heater core or radiator corrosion may result. In addition, the engine coolant will require change sooner-at 50 000 km (30,000 mi) or 24 months.

The following notice applies to the 4.8L, 5.3L, and the 6.0L engines only.

Notice: DO NOT use cooling system seal tabs, or similar compounds, unless otherwise instructed. The use of cooling system seal tabs, or similar compounds, may restrict coolant flow through the passages of the cooling system or the engine components. Restricted coolant flow may cause engine overheating and/or damage to the cooling system or the engine components/assembly.

Important: If you do not follow the procedure below, a low or high coolant level condition and/or vehicle damage could result.

1. Park the vehicle on a level surface.
2. Follow the steps below in order to remove the radiator surge tank fill cap:

•	Slowly rotate the cap counterclockwise.

•	Stop rotating and allow the hissing to stop.

•	After all hissing stops, continue turning counterclockwise in order to remove the cap.

3. Remove the drain hose from the left side of the radiator tank and repositon the hose to a catch pan.
4. Open the radiator drain cock.
5. Allow the system to drain completely.
6. Inspect the engine coolant:

•	Discolored -- follow the flush procedure below.

•	Normal in appearance -- Continue with the next step.

7. Close the radiator drain cock.

Important: When filling the cooling system use a 50 to 60 percent concentration with DEX-COOL® coolant.

8. Fill the system through the radiator surge tank opening.
9. Pre-mix a 50 to 60 percent solution of DEX-COOL® and clean, drinkable water.
10. Slowly add the pre-mixed solution to the system until the level is slighlty above the surge tank split line.
11. Start the engine.
12. Idle the engine for 1 minute.
13. Loosely install the surge tank cap. Do not allow the system to build pressure.
14. Cycle the engine from idle to 3000 RPM in 30 seconds intervals until the engine coolant reaches 99°C (210°F) and the thermostat opens.
15. Shut off the engine.
16. Refer to step 3 in order to remove the radiator surge tank cap.
17. Start the engine.
18. Idle the engine for 1 minute. Fill the surge tank to ½ inch above the COLD FULL mark on the radiator surge tank.
19. Install the radiator surge tank cap.
20. Cycle the RPM. Idle the engine to 3000 in 30 second intervals until the engine coolant reaches 99°C (210°F).
21. Shut off the engine.
22. Top off the coolant, as necessary, to ½ inch above FULL COLD mark on the radiator surge tank.
23. Rinse away any excess coolant from the engine and the compartment.
24. Inspect the concentration of the coolant.

Important: Do not use a chemical flush.

1. Block the drive wheels.
2. Place the transmission in park (P) or neutral (N).
3. Engage the parking brake.
4. Run the engine until the thermostat opens.
5. Stop the engine.
6. Follow the drain and fill procedure using only clean drinkable water. Repeat the procedure if necessary, until the fluid is nearly colorless.
7. Fill the cooling system.