You should flush and fill your car’s antifreeze every five years, though this may vary slightly depending on your specific vehicle. Here is a general guide on how to flush and fill coolant for most vehicles.
Step 1 - Cool Down
The engine should be completely cool before starting an antifreeze flush. If your vehicle does not have a lot of clearance, jack up the front end to gain easier access. Antifreeze is harmful to skin, so make sure you wear a pair of safety gloves for this project.
Step 2 - Locate Fill Cap
Pop the hood and locate the reservoir that holds the antifreeze. You will need to take off the fill cap to drain the antifreeze. To find the fill cap, check the radiator, pressure tank, engine, or hoses.
Step 3 - Find the Petcock
The petcock is a shut-off valve that will drain the antifreeze. It's usually found under the radiator tank and might have a plastic cover over it. You can remove the cover with a small screwdriver.
Step 4 - Drain the Coolant
Put the drain pan directly below the radiator and turn the petcock to drain the old coolant. With some vehicles, you might have to loosen a hose to drain the fluid. After the old antifreeze has fully drained, tighten the petcock.
Step 5 - Recycle
The old antifreeze is technically classified as hazardous waste, so auto part stores cannot accept it for recycling. You will need to contact your local waste department for information on recycling hazardous materials.
Step 6 - Clean Antifreeze Reservoir
Pour the radiator cleaner into the radiator along with some water, per the instructions found on the cleaner. Once this is done, tighten the radiator cap back in place.
Step 7 - Startup
Start the engine and run the heater on max until the car is operating under normal temperatures. Then shut the car off and allow it to cool down before proceeding.
Step 8 - Drain
Undo the fill cap once again and unscrew the petcock to drain the cleaning solution. Tighten the petcock once the fluid is finished draining.
Step 9 - Add Water
Keep the fill cap off and add water to the system via a garden hose. Check the vehicle manual to find out how much water you need to add. Once this is complete, put the fill cap back on.
Step 10 - Startup
Start the engine a second time and allow it to hit normal temperatures. Turn everything off and let the engine fully cool down.
Step 11 - Drain
Unscrew the petcock and drain the water. Ensure the petcock is closed before going on to the next step.
Step 12 - Rinse and Repeat
You need to repeat the water flushing a few more times. If you are concerned about the minerals in tap water, you can always use distilled water instead. After you drain the system, make sure the petcock is fully closed before adding the new coolant.
Step 13 - Add New Antifreeze
It is generally recommended to use pre-mixed antifreeze when performing a flush and fill because you do not have to worry about mixing it yourself. You can find pre-mixed coolant at your local O’Reilly Auto Parts store. If you want to use full strength antifreeze, you will need to add water to the coolant at a 50/50 ratio. Once the coolant is added, make sure all the caps have been tightened into place.
Step 14 - Startup
With the new coolant added, start the engine. Let your vehicle run for another 10 minutes after it has reached normal temperatures. Watch for any leaks under the car while it is running.
Step 15 - Cool Down
If you do not notice any leaks, turn off the engine and let it cool down. Then check again for any leaks and add more antifreeze if it is low.