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Antifeeze flush

I am planning on getting my cooling system flushed out and was wondering what is all involved with that process, what should the place I go do when it comes to doing a flush, is there different types of flushing? Also what should be a fair cost to do something like this?

My car is a 2003 Impala with about 123,000 miles on it, I don’t know when the last time a coolent flush was done, I bought the car in Dec 2014 and have not done while owning it.

Unless you’ve neglected maintenance, you likely don’t need a flush. Just have the cooling system drained and refilled.

If you’re going to do a flush, don’t let anyone do a chemical flush. It could damage your head gasket, especially if they don’t get all the flushing chemicals out. Go to an auto parts store, buy a simple flush and fill kit that hooks up to your garden hose, and flush the system yourself with clean water. Then, after you drain out as much water as possible, refill the system with either pre-mixed antifreeze/coolant or buy it concentrated and mix in equal parts with distilled water.

Otherwise, just have the cooling system drained and refilled. That is all that is likely called for in your car’s maintenance schedule. Don’t let some hack sell you what you don’t need.


Agree! But this is a good time to have it pressure tested as well. All hoses and connections should be inspected and replaced if necessary.

Here’s the coolant flush machine I use.

You fill the tank with a 50/50 mix of coolant and connect the machine between the upper radiator hose and the radiator.

Then you turn the machine on, and it replaces all the old coolant with new coolant while at the same time pressurizing the cooling system to it can be checked for leaks.


While you’re doing all that, you might as well install a new radiator cap.

I would suggest that you go to a autoparts store, or the autoparts section of Walmart and get a cheap antifreeze tester. You can get a simple glass tube type with the floating balls for a dollar, this is all you need for this.

Draw a sample of coolant from your radiator or overflow reservoir. If the sample is a clear color, like red, yellow, pink or green, you do not need a flush. I fact nothing is urgent at this time but you should change your coolant as soon as convenient.

If it is cloudy, you should have the coolant changed ASAP, but it does not need to be flushed, a drain and fill is all you need.

If it is muddy and brownish, then you need to have it flushed ASAP. I would not allow any chemicals to be used, It should be done @Tester’s way.

Unless it is muddy and you are having overheating issues. If things are bad enough, it may take some chemicals to get things flowing again, but I would have the radiator removed and cleaned in an external chemical bath so that the chemicals do not attack other parts of the engine or cooling system components.

I do apologize, I ment just a drain and refill I didn’t mean anything as drastic as some perceived when I said flushed. Given I don’t know how old the fluid is in the car, and I did have to add maybe a couple of cups last week as the system was a tad low I thought it might be a good time to have all the old antifreeze drained out and new fresh put in and at that same time have them check the hoses and such.

If the coolant is clear, then the corrosion inhibitors are still good. As they get used up, they turn cloudy. When it gets brown and muddy, it is doing damage to the cooling system.

There is nothing wrong with having your cooling system flushed on a machine like @Tester’s, but it does cost more. If your coolant is clear, that is just an extra expense, but it won’t hurt.

if you do everything that has been suggested in this thread, it’ll cost you easy $300, especially if you go to one of those nation-wide stores. My suggestion is…don’t touch it if it ain’t broke. Just do regular maintenance and check all fluids frequently.

Are you responding to a different thread?


if I did, it would hardly show up here, right?

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Where are you coming up with that price of $300.00 for a cooling system service?


It doesn’t make sense here. Cooling system maintenance is a part of scheduled maintenance and needs to be done or the life of the vehicle will be shortened. A drain and fill or flush can cost over $200 at most places, but it still needs to be done. Surely you didn’t mean for the OP to ignore this.

Edit: over $200 at a dealership anyway.

When use my flush machine, it costs $50.00 plus the cost of the antifreeze/coolant and a new pressure cap.


I disagree. If the coolant color does not indicate a problem there is no need for a flush. Unlike oil, the coolant does not break breakdown. A pressurized flush can only cause more damage to a perfectly working cooling system, by dislodging parts that now get stuck somewhere in the system and potentially cause problems.

The Internet is full of overheating examples after a flush.

Old coolant loses it’s anti-corrosive package and the lubricant for the water pump over time.


I googled overheating after flush and after a couple of pages, all had overheating problems before the flush. The cooling system is designed to hold at least 15 psi.

The corrosion inhibitors get used up in antifreeze and they turn cloudy when they do.

My coolant flush machine doesn’t exceed the cooling system’s normal operating pressure.

If it did, the pressure cap would blow open and none of the coolant would be replaced.

And I love these urban myths.

"by dislodging parts that now get stuck somewhere and potentially cause problems.

If you’re dislodging parts, gunk, sludge, chunks, etc…, it means the system wasn’t maintained to begin with.


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My last coolant service ditched dexcool for a universal antifreeze, dexcool can sludge under certain conditions, and at your cars age I would reccomend peak global or similar.

It sounds like you have a good plan there OP. Just draining the old coolant out, disposing of it in an environmentally and pet-friendly way, and adding fresh coolant spec’s to what the manufacturer requires back in is basically all you need to do. Going beyond that could prove beneficial in preventing future cooling system problems, but unless you have cooling system problems, not required.

fyi, if interest, when I do this on my Corolla, here’s what I do

  • with engine cold, and inside heater control at max flow, open the radiator cap, then open the valve at the bottom & drain the radiator.
  • fill the radiator with tap water to about 2 inches below the top, start the engine and let it run until the radiator fan turns on. a little water/coolant may overflow the top of the radiator when the thermostat opens.
  • let the engine cool off again
  • drain the radiator and repeat the water fill, engine idle until fan turns on
  • let the engine cool off again, then drain the radiator one more time
  • now refill the cooling system with fresh coolant, and you’re done
    Note 1: In most cases you want to have a ratio of water to coolant of 50%. Since the amount of coolant you get out of the radiator isn’t the total amount in the cooling system, and since what remains in the system at this point is mostly pure water, I have to add a stronger strength coolant mixture than 50% in order to end up with 50% once it all mixes together. How much depends on the ratio of the radiator volume to the coolant system volume. In my Corolla’s case the radiator and cooling system hold about equal amounts, so I just add pure 100% coolant but leave a little extra room in case I need to add some water to end up with 50% after it all mixes together.
    Note 2: Many folks say to use distilled water, but I’ve always used tap water and never had a problem. What exactly is in tap water varies by location and by the seasons, so using distilled water (which is a known and unambiguous thing) might be the better thing to do. Unlikely to hurt, except your wallet a little.
    Note 3: On some vehicles bleeding all the air out is another job. On the Corolla all I have to do to get the air out is open the radiator cap and run the engine until the upper radiator hose begins to feel hot.