Tuesday question: I have a 2003 C5, can you get to the drain plug with the car still on the ground? Or do I need to get the car up in air?

Draining and Filling Cooling System

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.

Important
If the procedure below is not followed a low or high coolant level condition and/or vehicle damage could result.


You need to have the rear end higher for draining. You need the nose higher for filling. This will get the air out of the system.

1) Park the vehicle on a level surface.
2) Remove the surge tank cap:
3)Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
4) Place a drain pan under the drain petcock.
5) Open the radiator drain petcock. ¼ turn counter clockwise then pull out
6) Allow the cooling system to drain completely.
7) Inspect the engine coolant for the following:
Discolored -- follow the flush procedure below.
Normal in appearance -- continue with the next step.

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.


8) Close the radiator drain petcock. Tighten.
Tighten the radiator drain petcock to 2 N•m (18 lb in).
9) Fill the cooling system through the surge tank.
10) Fill the cooling system with a 50/50 mixture of DEX-COOL® coolant and water.
11) Start the engine.
12) Allow the engine to idle for 1 minute.
13) Install surge tank cap.
14) Cycle the engine RPMs from idle to 3000 in 30 second intervals until the coolant temperature reaches 99°C (210°F).
15) Shut off the engine.
16) Remove the surge tank cap.
17) Start the engine.
18) Allow the engine to Idle for 1 minute. Fill the surge tank to 12.7 mm (0.5 in) above the COLD FULL mark on the surge tank.
19) Install the surge tank cap.
20) Cycle the engine RPMs from idle to 3000 in 30 second intervals until the coolant reaches 99°C (210°F).
21) Shut off the engine.
22) Remove the surge tank cap.
23) Top off the coolant as necessary, 12.7 mm (0.5 in) above FULL COLD mark on the surge tank.
24) Rinse away any excess coolant from the engine and the engine compartment.
25) Inspect the concentration of the engine coolant.
26) Install the surge tank cap.

The radiator drain is at the lower, right corner of the radiator. Open it, let it run until the flow stops, close the drain and refill the system with water. Run the engine until the thermostat opens, shut off the engine, carefully release the pressure in the cooling system and open the radiator drain again. Repeat this procedure until the coolant coming out of the radiator runs clear. You may need to do this tedious flushing trick several times to get the water to run clear.Once the flushing is done, close the drain and fill the system with a 6.5 qts. of Dex-Cool (50%). Add distilled water until it reaches the base of the surge tank neck. Start the engine and let it idle for a minute then cycle engine speed from idle to 3000 rpm and back until coolant temperature reaches 210¡F. Remove the tank cap, observing the cautions discussed previously. The coolant level should be about 1/2-in. above the "cold full" mark on the tank. If it is not, top off with distilled water, replace the cap, start the engine and repeat the above procedure.

Draining and Filling Cooling System

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.

Important
If the procedure below is not followed a low or high coolant level condition and/or vehicle damage could result.


You need to have the rear end higher for draining. You need the nose higher for filling. This will get the air out of the system.

1) Park the vehicle on a level surface.
2) Remove the surge tank cap:
3)Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
4) Place a drain pan under the drain petcock.
5) Open the radiator drain petcock. ¼ turn counter clockwise then pull out
6) Allow the cooling system to drain completely.
7) Inspect the engine coolant for the following:
Discolored -- follow the flush procedure below.
Normal in appearance -- continue with the next step.

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.


8) Close the radiator drain petcock. Tighten.
Tighten the radiator drain petcock to 2 N•m (18 lb in).
9) Fill the cooling system through the surge tank.
10) Fill the cooling system with a 50/50 mixture of DEX-COOL® coolant and water.
11) Start the engine.
12) Allow the engine to idle for 1 minute.
13) Install surge tank cap.
14) Cycle the engine RPMs from idle to 3000 in 30 second intervals until the coolant temperature reaches 99°C (210°F).
15) Shut off the engine.
16) Remove the surge tank cap.
17) Start the engine.
18) Allow the engine to Idle for 1 minute. Fill the surge tank to 12.7 mm (0.5 in) above the COLD FULL mark on the surge tank.
19) Install the surge tank cap.
20) Cycle the engine RPMs from idle to 3000 in 30 second intervals until the coolant reaches 99°C (210°F).
21) Shut off the engine.
22) Remove the surge tank cap.
23) Top off the coolant as necessary, 12.7 mm (0.5 in) above FULL COLD mark on the surge tank.
24) Rinse away any excess coolant from the engine and the engine compartment.
25) Inspect the concentration of the engine coolant.
26) Install the surge tank cap.

The radiator drain is at the lower, right corner of the radiator. Open it, let it run until the flow stops, close the drain and refill the system with water. Run the engine until the thermostat opens, shut off the engine, carefully release the pressure in the cooling system and open the radiator drain again. Repeat this procedure until the coolant coming out of the radiator runs clear. You may need to do this tedious flushing trick several times to get the water to run clear.Once the flushing is done, close the drain and fill the system with a 6.5 qts. of Dex-Cool (50%). Add distilled water until it reaches the base of the surge tank neck. Start the engine and let it idle for a minute then cycle engine speed from idle to 3000 rpm and back until coolant temperature reaches 210¡F. Remove the tank cap, observing the cautions discussed previously. The coolant level should be about 1/2-in. above the "cold full" mark on the tank. If it is not, top off with distilled water, replace the cap, start the engine and repeat the above procedure.
No need to go any further than what Tim has posted here!!! Nice work Tim!!:cheers: