Coolant!
 

I know there have been other threads discussing coolant in the past, but I'm looking at changing my coolant in the spring and I'm wondering if things have changed since the last discussion.

What kinds of coolant are people using on FDs now, and how often do you change your coolant?

The Mazda pre-mixed FL-22 extended life coolant looks like a no-brainer to me.

Automobile-catalog says the coolant capacity is 8.7L, so that would be 3 jugs of the 3.78L FL-22, I think. I'll check the service manual when I get home just to be sure.

I’ve been using full-strength Prestone (regular green type) diluted 50/50 with distilled water, and renew it about every 12 months or so. Pick it up at Walmart, they seem to have the best price in my area.

Use whatever you want so long as its green. It allows you see more easily when its dirty or if you have a bunch of loose crap in your cooling system. Unless its Evan's, it really doesn't matter what you use so long as its green for the reason mentioned above

I use the FL-22 in my RX-8 but for the FD I use green Prestone and distilled water.

The FD was made before a lot of the new long life coolants. Some of the seals and such may not be compatible with the chemicals in newer coolants. Really there's no good reason to run something else.

1 gallon of Prestone green full strength, 1 gallon of distilled water, change it once a year. You do that and you'll have a coolant system that's bright and shiny inside. There's no reason to do something different.

Dale

Thanks, guys!

Looks like this is the stuff: https://prestone.com/product/preston...freezecoolant/

And I found this handy guide from Racing Beat as well: https://www.racingbeat.com/mazda/per...r-cooling.html

Mazda has an undiluted green coolant, 0000-77-501E-02, very similar to the factory fill.

Thanks, I'll look around for it – doesn't seem to be listed on the Canadian sites.

Green pre diluted prestone here with some water wetter.... actually I use Royal Purple ice additive or whatever it is called. Water wetter I think is redline.

I've been using full strength undiluted Ethylene Glycol-based green or yellow coolant in all cars since switching the FD to Evans over a decade ago. High humidity tropical climate 80-95 F all year.

FD - Evans for over 10 years, never changed it but topped up with full strength EG green when coolant lost for whatever reason.
2000 Protege 1.6L crashed at 270k miles, running undiluted EG since about 100k
2006 Mazda 5 2.3L 230k, running undiluted EG since 100k
2009 Infiniti FX-50 5.0 V8 - 125k, running undiluted EG since 50k

Based on your lack of freezing temperatures I'd probably run distilled water with maybe 25% coolant concentrate. Running 100% concentrate in the temperature just seems silly.

In addition to, IMO, being silly, undiluted ethylene-glycol AF (green) neither cools or prevents freezing nearly as well as 50/50. Undiluted AF or Evans is only, IMO, useful in a show vehicle.
https://cimg4.ibsrv.net/gimg/www.rx7...00bbe78dd6.jpg
https://cimg0.ibsrv.net/gimg/www.rx7...832f0ce588.jpg

Anyone know the difference between these 2 offerings from Prestone? AutoZone charges $12 for the "All Vehicles" and $20 for the "Asian Vehicles."
They look to be the same to me.

Prestone® Asian Vehicles (Green) Antifreeze
https://prestone.com/product/preston...freezecoolant/

and

Prestone® All Vehicles Antifreeze + Coolant
https://prestone.com/product/preston...-ready-to-use/

May just be the absence of the borates and silicates similar to red Asian coolant.

I just use the regular Prestone, then mix with some distilled water.

The Mazda FL-22 is green, so that may be Prestone's knock off of it.

Again, plain regular Prestone is the way to go. I get a gallon of the regular undiluted stuff and a gallon of distilled water. That will totally fill up the system.

Change it once a year and you'll have a happy cooling system.

Dale

I'm testing out the Pentosin brand FL-22 50/50 pre-diluted coolant in my FD. It's a green/blue color, basically the same as Mazda's FL-22 coolant. I've always used and still use the regular full strength Prestone green ethylene glycol coolant, diluted to 50/50 with distilled water in my FC. As for change intervals, I change the FC yearly, and I'm going to try going 2 years with the FD - supposedly the FL-22 can go a lot longer than that, but I don't want tempt fate.

Since both cars will come due for coolant changes around the same time next year, it will be a great opportunity to inspect the drained coolant and any visible surfaces to see if there's more/less evidence of corrosion in one or the other car.

Evans NPG+. Love the stuff...... lasts a lifetime and runs at zero pressure. As long as you have an upgraded radiator and oil cooler(s), in my experience you're good to go.

Been running it in my '95 for like ten years, my brother's SSM has been running it for about the same, have converted over numerous customers and buddy's FDs.

I have a bunch of prep fluid (Sierra pet-safe coolant) and NPG+ in the garage to convert my 20B car and the Montego Blue to it this summer :)

FWIW, part of my spring coming-out routine is that while it’s on the lift I drain a gallon or so from the radiator and replace it using a Lisle funnel. My thinking is that doing it annually I keep everything fresh but since I don’t drain enough to empty the block the t-stat opens ALOT sooner. And the funnel still keeps air out of the system.
I use a 50/50 mix of the FL-22.

I would suggest Paying attention to the ingredients in any coolant you use. I noticed recently that there are several different compositions of the usual green coolant with varying percentages and types of OAs. These are Organic acids which may not be compatible with older materials; as anyone who has used Dexcool in their system may know having encountered swelling of certain rubber components.

I don’t believe OAs were in common use when the FDs were built. Dexcool was the first big venture into their widespread use afaik, and it was problematic to say the least. OAs are more common today but I try to avoid them, at least for older systems. OAs are, I believe, intended to extend the life of the coolant and to replace some of the other more toxic compounds used older formulations.

You can check the specific gravity of the coolant and stick a multi meter probe into it and determine it’s concentration and electrolytic condition. I have never had coolant go bad in less that three years—for the older formulations, and newer ones are seem to last a lot longer. In my experience, I have not seen any evidence, other than peace of mind, to support annual coolant changes—even when running weak concentrations. This is for ethylene glycol based coolants; I can’t speak to the Polys such as Evans as I have not used them.

the advantage to Evans is it doesn’t boil over on a hot shutdown. Anyone who owns an RX8 can appreciate this, but it’s a fairly common rotary engine issue in general.

Needs to be stressed that getting all the water out the system prior to using it is critical though. Otherwise it can turn corrosive fairly quickly. That said I can’t claim any performance benefit for using it other than it’s not going to boil even in an engine overheat situation. I always felt that this added some buffer against losing the engine it that happens.
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Evans = no water= no corrosion=no pressure= no boil= win win

Evans is a great product but it's not for me. If I'm in the back woods of North Carolina and have a coolant hose fail, I can simply repair it and fill the coolant with regular Prestone and I'm back on the road. Not so with using an exotic coolant.

I only recommend Evans in specific use cases. For the majority of people, Prestone and distilled water is all you need. It's cheap, it's easily available, and with doing a drain and fill every year or two you will have a spotless cooling system. I've gone through engines with a LOT of miles (like 150-160,000) and were treated with Prestone as stated, they had spotless bright clean cooling passages.

IMHO there's no good reason to try something else. This car is exotic enough as it is.

Dale

You’d just have to fill it with water or coolant and start over again, but mine is mostly off road use. I don’t try to push it on anyone, but only share my experience. I agree with your thoughts though. The biggest issue is having a fill it and forget mentality. Doing as you suggest is going to keep the the system in top shape. I also believe in swapping out the hoses rather than waiting for a problem to crop up. It’s more of an observation/intuition situation than putting a number to it though.
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I think for my upcoming coolant flush/change I'm going to give the Zerex blue a try for Asian Vehicles. Non 2-EHA and HOAT. Not that I'm expecting any superior difference, but I thought I'd give it a try.