What type of coolant to use?



Hi there,

Vehicle is a 2007 Mazda 6 S V6 3.0L. I would like to know if there is a specific coolant I should be using for this vehicle. The owner’s manual doesn’t mention the specific coolant other than “if the cap has FL22 on it the cap, use FL22 type coolant”.

Is it okay to use a 50/50 Coolant on this vehicle? Does the color matter? Say, if I do a flush? Any recommendations or suggestions?



If your cooling system is working fine, then DO NOT FLUSH. Flushing often does more harm than good, especially if you use a chemical flush.

You can get this coolant at your Mazda dealer. You can also look into using Peak Global or Zerex Asian. Look at the section on the label that says “Meets the following specs…” and see if FL22 is listed.

FL22 is a longlife ethylene glycol antifreeze. The basic antifreeze is common to most brands. Most brands use a Hybrid Organic Acid Technology (HOAT) for keeping the cooling system clean and corrosion free. Different auto manufacturers have made slight changes in the HOAT formula and recommend it for their vehicles, but since you are not under the manufacturers warranty, you are not obligated to use this formula.

Any long life, mixes with any color, universal antifreeze will work just fine. The FL22 from the dealer is already premixed at 50/50 with deionized water. You can use any 50/50 premix or mix your own with a full strength antifreeze and distilled water.

You don’t need to flush if you don’t have a problem. You are mainly replacing the corrosion inhibitors so a little of the old coolant left behind will not hurt anything. It will be less harmful than some of the contaminants that often get into the cooling system from flushing.

Edit: If using the FL22 will make you sleep better at night, then use it. It probably isn’t that much more expensive than the brands available at your parts store or big box store, maybe a buck or two. It may be just a hassle or a long drive for you to get to a Mazda dealer to get the stuff. You might try Amazon too.

Edit: Mazda has two coolants, both HOAT long life coolant but one is not FL22. Amazon does carry it. IMO, both would work for you as would any other long life HOAT coolant, but if it makes you comfortable, use the FL22.



Hey Keith, thanks for replying.

So I can use FL22 Mazda Coolant even if my car doesn’t have the FL22 marked on the cap?

I was curious about the different coolant colors and thought of doing a google search about it. I read some people said you can’t mix colors and some were saying that you should never mix regular coolant with DEXCOOL. So there is a lot more about coolant than I initially thought.

When I replaced the water pump on my Mazda 6 I bought the cheapest coolant from Oreilly thinking it would be okay since the manual didn’t say much other than the capacity. If I remember correctly, the car had green coolant, or maybe not, because it was leaking so badly that there was hardly any coolant in it. My brother just used plain water since it was leaking fast. So I just bought a 50/50 that turned out to be green too.


If FL22 is not on the cap, it wont hurt to use it, but why would you go to all the trouble to get it if it isn’t specified? As I said, any HOAT long life universal coolant will work just fine, but some people sleep better if they are using what the factory calls for, and a good nights sleep has value.


What if it’s an aftermarket Stant radiator cap?

In that case, it almost certainly won’t say FL22 . . .


The spec I’m seeing is the same as what you report: If there’s a label saying to use FL22 coolant on or near the radiator cap, that is what must be used. The spec doesn’t say what to use if there’s no label, which seems a little unclear. You’d think they’d say “use fl22 if there’s a label, and if no label use … XXX”. I guess clarity for the customer wasn’t the intention. hmm … if I had that problem I’d take the car & the owner’s manual to the dealership and ask them to interpret what it means. They probably get people coming in all the time asking this same question, so they’ll likely know straight-away. My guess – only a guess — is that they’ll tell you that you can use any generic ethylene glycol coolant (e.g. Prestone) if it doesn’t specify fl22 on or near the radiator cap.

The reason there are different spec’s of coolants is b/c the engine innards are made of coolant compatible components, and only certain types of coolant are compatible with those components. Using the incorrect coolant may eventually degrade material on the inside of the engine. Which as you might expect is not a good thing. Engines of yesterday – like my 45+ year old truck – were made mostly of cast iron, which is more forgiving. Today’s engines have lots of aluminum and other even more exotic stuff inside that the coolant contacts, and hence, the need for specific coolants.

For generic coolants, 50/50 is a good mix for most climates. In extremely cold climates I think you can go as high as 70 % coolant, 30 % water. Read the label on the coolant container. It will tell you what mix to use. A lot of auto parts store coolants these days are already pre-mixed, so there’s nothing to do. Like I say, read the label.


Hey George!

Did you know that the universal coolants were demanded by the military?

Because the military posses so much equipment that dates back to who knows when, where different coolants are required, they finally said one spec, one coolant.

That’s how we got universal coolants.