Manual says to flush cooling system with water, but they don't sell coolant concentrate?

[Mike_R]

The owners manual says to replace the coolant at 120,000 miles/10 years and the service manual says that replacing the coolant involves flushing the cooling system with water until it runs clear, and to only use FL22 coolant but Mazda doesn't sell FL22 concentrate.

How can you then replace the water used to flush the cooling system with coolant If there's not a concentrate?
Because each drain and fill will only replaces half the water/coolant, it would take 4 gallons of the FL22 just to replace 94% of the water that was used to flush.
I would buy aftermarket coolant concentrate but I don't know that there's a way to verify they offer the same protection as FL22.

 

[wlong01]

I had the coolant replaced in my 2019 yesterday. 52k on odo but wanted it done because of the TSB and problems related to the previous coolant corroding the heater core.
Not sure how they did it but they used one gallon of coolant. Capacity is around 8 qts so the rest must of been distilled water.
Total price was $79.00.

 

[Logidad]

The owners manual says to replace the coolant at 120,000 miles/10 years and the service manual says that replacing the coolant involves flushing the cooling system with water until it runs clear, and to only use FL22 coolant but Mazda doesn't sell FL22 concentrate.

How can you then replace the water used to flush the cooling system with coolant If there's not a concentrate?
Because each drain and fill will only replaces half the water/coolant, it would take 4 gallons of the FL22 just to replace 94% of the water that was used to flush.
I would buy aftermarket coolant concentrate but I don't know that there's a way to verify they offer the same protection as FL22.

If the radiator cap has FL22 on it that's what you should use, otherwise feel free to use an OAT type coolant. Start the car and turn the heater on "high" and wait 30 seconds. This allows the heater core to to drain as it's valve is wide open. Drain the system at the rad with the cap on the radiator removed. Detach and drain the overflow bottle. Yes you probably need two premixed bottles (possibly 3) of the right type of coolant. In essence you are doing "drain and fill twice". If you're adamant about flushing with water, you'll likely have to go to a serious amount of work. What you are really trying to accomplish, besides preventing freezing, is reducing the acidity of the coolant. Acid and aluminum parts do'nt play well together nor do some head gaskets. My VOM meter registered .06 volts when checked between the coolant and engine block but my truck had 1.2 volts and needed changing. Thats's acidity at work and by time you flush twice you have indeed removed about 80% of the old coolant. I would be interested in the exact procedure the dealers use because $79 seems like an awfully low price.

 

[wlong01]

II would be interested in the exact procedure the dealers use because $79 seems like an awfully low price.

Invoice just says Coolant Maint., Drain/Fill, checking belts, hoses and water pump.
$29.00 Coolant $50.00 labor.

Sounds like they drained a gallon and put a gallon in. Hopefully it will give some better corrosion protection. That was my objective.