Once the entire cooling system is flushed and you're in a maintenance mode, you can get in a simple and easy habit of managing your cooling system by doing the following to drain and refill the radiator each fall (with very few air bubbles or any at all):
1. With a cool or cold engine, shut-off the ignition to turn the engine off. Do not restart until after you are finished with these steps (below).
2. Remove the Radiator Cap.
3. Unscrew the petcock on the bottom of the radiator and let the old coolant drain into a bucket or drain pan.
4. Tighten the petcock on the bottom of the radiator.
5. SLOWLY refill the radiator to the top with a 50/50 blend of your favorite antifreeze - allowing air in the empty radiator to rise to the top and out the inlet hole.
6. Start the engine and let it idle for a couple of minutes. Only a few air bubbles from the top of the radiator should be seen.
7. Fill the coolant overflow reservoir to an inch or two about the full line.
8. Once the coolant begins to rise or overflow the inlet spout, put the radiator cap on and secure it in place.
9. Drive the vehicle a few miles and inspect for leaks around the petcock drain plug.
10. Inspect coolant overflow reservoir to ensure it's at or a little above the full mark.
The radiators of most cars take 3/4 to 1 gallon of coolant. Performing a simple 10 minute drain and fill of the radiator each fall will prevent many cooling system problems in the future.