How to flush your coolant?

Just like every system in your vehicle proper maintenance is going to ensure that your vehicle runs just as well as the day it was driven off of the assembly line.

Ensuring that you flush the coolant at the manufacturers specifications is an important maintenance item. It used to be a coolant flush was recommended at roughly 100,000miles but I have recently noticed many vehicles with extended life coolants.

These extended life coolants can reach intervals of more than 150,000 miles before they need to be flushed.

Always remember that you can flush your coolant earlier if you want to ensure the cooling system is properly protected.

You should always check your coolant strength every oil change or two to ensure that the vehicle has proper freeze protection. Coolant has the ability when mixed properly to protect an engine easily down to -40°F.

As coolant breaks down, or someone has done a top up with plain water this freeze protection increases in temperature and does not properly protect the engine. Properly flushing your coolant will ensure that this weak coolant is replaced with the correct mixture.

So, lets go through all the steps of how to flush your coolant?

Steps to flush your coolant.

1. Raise vehicle on hoist, or jack stands. (Ensure safe stands are used)

2. Once engine is cold, remove the radiator cap. (This will help the coolant drain faster)

3. Place a correct drain pan underneath of the vehicle to ensure that coolant is collected properly.

4. Locate the lower radiator hose or drain cock. Once located either remove lower rad hose or loosen drain cock until fluid begins to drain from radiator.

5. Allow coolant enough time to drain from the cooling system. Stop and have a coffee, that’s what I do.

6. Once coolant has drained, tighten the drain cock or re install the lower rad hose.

7. Fill system with cooling system flush liquid, follow instructions on bottle.

8. Run engine for prescribed time as per instructions on the bottle.

9. Drain cleaner and water as per instructions. It is very important that at this point you allow all of the cleaner and water to drain from the cooling system. The cleaner is designed to run through the system temporarily and can cause damage if left in for extended period of time.

10. Fill system with fresh coolant. Ensure that the coolant you use meets or exceeds OEM recommendations.

11. Turn heat on high, run vehicle at 1500 rpms for about 15 minutes. You should see the coolant level bubble and decrease in level as the air in the cooling system bleeds from the system. Once all of the air is out of the system the heat will blow warm and no more bubbles will be seen.

12. Test the coolant freeze level using the correct tool to ensure coolant is mixed properly. Compare to this chart to ensure you have proper freeze protection.


13. Dispose of coolant properly at your local landfill.

14. Congratulate yourself for a job well done and money saved.

While a coolant flush can be a great do it yourself task for the person with average mechanical abilities a few precautions should be followed.

Ensure that your wear correct personal protective equipment. Coolant is poisonous and can cause skin and eye irritation or more serious issues if ingested.

When using coolant from concentrate use only distilled water when you are mixing to the correct ratios. With todays extended coolant flush intervals the hard water deposits in tap water can build up on the internal components of your cooling system causing damage.

Use only the correct manufacturers specified coolant. With today’s modern coolants serious issues can arise when mixing coolants. Some coolants have been known to react to each other and turn into a gel like substance when mixed.

As you can imagine this is not a good situation to have happen to your engine.

Hope you enjoyed the guide on how to flush your coolant. We have a great source of automotive information in this website, take a few minutes to take a look around.

Staff Writer
Staff Writer
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