Let the engine cool completely
Park on a level surface and set the parking brake
Open the hood and locate the radiator cap and drain plug
Place a drain pan under the radiator
Remove the radiator cap
Open the radiator drain plug or petcock
Drain the coolant completely
Close the drain plug or petcock
Fill the radiator with distilled water or a radiator flush solution
Start the engine and let it run for the recommended time
Turn the engine off and let it cool completely
Drain the radiator again
Repeat with distilled water until the drained water runs clear
Close the drain plug or petcock
Refill with the correct coolant mixture
Top off the coolant reservoir
Reinstall the radiator cap
Run the engine and check for leaks
Check coolant level again after the engine cools
Dispose of old coolant properly