Over the years I’ve tinkered with a bunch of different cars. Back in the day, you could put green ethylene glycol coolant in every car and it worked fine. If you had a car with the brand new DexCool, it was recommended to drain it and refill with the green stuff. Then some manufacturers went to the red stuff, and VW/Audi went to some other stuff that sludges up if mixed with the green stuff.

A couple years ago I bought an insurance auction VW Beetle TDI, and when I replaced the front end/radiator/etc., I flushed the engine out with water and switched the car to traditional green coolant.

My ’06 Mustang has 140K on it, and living in a constant state of having too many projects, I’ve neglected to change it until now. I’m of a mind to flush it out and run green coolant, but I know aluminum motors aren’t exactly tolerant of the green stuff.



I intend to transition my entire fleet to one coolant. What is a good one-size-fits-all coolant that is readily available? I’m in Oklahoma, and it freezes here, so running straight water is not an answer. Should I stick with the green stuff and replace it more religiously?

The Mustang is bone stock and ultra-reliable, so I don’t want to run coolant that has a propensity to turn acidic and erode the cooling passages. Is the red stuff any better? What is it called and can I find it at a truck stop at 3 a.m.? Does VW’s coolant have any advantage?

Please note that I both know and admire Mr. Strawn from his work building race cars in the 24 Hours of Lemons…the wretchedly wonderful Jaggernaut with the Big Block Cadillac motor notwithstanding.

That said, what you propose will never work these days. Engine coolant is now color coded for good reasons, apparently.

If I googled this correctly, your VW TDI uses G13: a purple colored, Silicate Organic Acid based coolant. The Mustang uses either a fully Organic or Hybrid Organic coolant (orange or yellow).  Neither should use the green stuff, that’s just clinging to old technology. Perhaps you can run the VW’s purple stuff in the Mustang, I doubt the opposite is possible without leaks, gasket failures, or expediting a possible plastic water pump impeller failure problem.

Not to mention that VW G13 coolant is usually a few bucks more than the yellow/orange stuff. A good color chart with the differences can be found here.

So do yourself a favor and blow out the green stuff, replacing it with the proper purple coolant in the VW.

Send your queries to [email protected]com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice. 

My ex’s 2016 Mazda3 was recalled due to potentially having an improper coolant mixture (not enough antifreeze). I tested it and it measured low so I called up the Mazda dealer. They didn’t stock FL-22 and told me they just use the regular green stuff. Probably tap water too. So I picked up some FL-22 and did it myself.

I’ve got a 99 and 2004 GMs that have run Dexcool with 5 year change intervals. The 04 is still all original parts. The 99 had a radiator fail two years ago but it looked more like external corrosion (salt belt). The 99 is a cast iron engine and the 04 is an aluminum engine.

Yeah, from what I’ve read and experienced Dex is fine as long as you don’t let it go for too long…I think GM spec’d 7 years, which was…optimistic. Its vice was eating plastic head gaskets, so probably not to blame for your radiator.

DexCool itself was never the problem. GM still uses it as factory fill to this day. The problem was GM put it into production before they were sure it was compatible with all of the materials it would come into contact with.

Several decades ago was going to overhaul the engine in one of my vehicles. The OEM coolant/antifreeze was, at the time, hard to find and over $50 a gallon in today’s money. While that is a small cost compared to cooling system failure I looked around for something else. At the time “long life” antifreeze was relatively new. There was Dexcool and G05. Read the horror stories about Dexcool and most appeared to be poor maintenance. I put Dexcool and distilled in the system and it’s worked fine. “Open the hood and check the coolant?? Does that involve beer and chips or TV??”

This. I’ve never experienced a Dex failure. I simply treat the first service interval as 5 years or 100K miles, whichever comes first, and then 50K miles or 5 years after that. I don’t care how good it looks or what it tests at. Do the same for tranny fluid.

Experiment at your peril, but don’t blame the coolant when the engine fails. Also- Amazon has VAG coolant for about half the cost of what the dealer wants.

G13 is a bit hard to source locally and more expensive than average but if your car is mechanically sound coolant leaks shouldn’t be an issue. It is good for 100k miles which is inline with the timing belt/water pump intervals. Green coolant is old tech and would need changed 3 times to 1 over 100k miles. All the sudden G13 doesn’t sound all that expensive.

The Ford is G05 coolant, is cheap and can be found at any parts store. I’ve never been a fan of “universal” coolants. Seems like a misnomer to me.

Not a good idea to mix coolants. Now a days if I need coolant I just go to the dealer most coolants are under 25 bucks a gallon. At one time you could use something like Peak global formula to replace coolants( I replaced my 3.8 Gm dexcool with this, the 5.7 didn’t have the same issues). Not so easy anymore. Most coolants easily last 150,000 miles so why chance it.

An important note. Be aware of the water that is used to flush the system. Many municipal water systems supply water with some mineral content, “hard water”. This usually alkaline water is corrosive to aluminum and not that good for cast iron. Most vehicles of the last 40 years make it near impossible to drain all the coolant/water, or whatever is in the system. Unless you turn the car upside down and shake it. This needs to be accounted for when refilling. Using 10-20% more antifreeze will prevent excess dilution. If the antifreeze is less than 30-40% of the mix, corrosion will happen a lot sooner. The anti-corrosion additives in the antifreeze will be used up in a relatively short time. I have seen many radiators, water pumps, and heater cores (do you want to take the dash out?)ruined by this. Ideally there should be nothing in the cooling system except antifreeze and purified or distilled water.

If you’re lucky, you have a car with drain valves or plugs in the block. Both of my Toyotas have them.

Beyond a mega emergency, there’s really no excuse to use hose water. A gallon of distilled water is like 75 cents and I used that for coolant system work even when I was working at Arby’s.

I wouldn’t have a problem using tap water to flush a system, as long as you drain it, fill it with distilled water, run it for a while, and drain the distilled water. Distilled water isn’t stable, so it will absorb any of those minerals you introduced.

That’s true, MBella. However since some fluid will not drain if a 50/50 mix of antifreeze and water is used to refill, it can be at 30-40% antifreeze or less. It’s a good idea to fill with 60% antifreeze or more. A typical V8 truck will have a gallon of fluid that cannot be drained in any reasonable way. That gallon is 20-30% of the total 4-5 gallon capacity. And I wonder about those “coolant flushing” machines. Are they really going to run xxx gallons of coolant through till the system is clean? What happens to the contaminated stuff that comes out? Do they put it in the next car?

Coolant flushing machines at best are just coolant exchangers. Usually not even that, because they’re not used properly.

As for the gallon of residual water, if you’re that worried about it, you can drain and fill it several times with distilled water. Also, keep in mind that any service facility will be using tap water.

The problem with using tap water to flush a system is just like the coolant your only going to dilute it at best when adding distilled. If it’s not good enough to use as a final fill I’m not sure it would be a good idea to use as a flush. Too many people give municipality water systems a free pass,lead, iron, cadmium and arsenic are all common in city water. And then there are people like me that have well water, our water is pretty good but we do have a two stage filtration system plus a water softener so your still going to end up with a small % of salt in the water. And some wells are high in calcium, iron, magnesium, and sodium to name a few. Whatever goes in your engine block is there to stay, it can’t be processed or diluted over time. So it really is best to just stick with distilled water.

But how much of this (coolant flushing) is relevant or needed anymore? With the technology of today’s coolant I think you would really have to neglect your system. 20 years ago, neglect was considered 100k miles without servicing your system. Now coolant is commonly rated for above that which gets many vehicles into a service of a timing belt, water pump or some other job that requires opening up the system. I’ve not flushed the cooling system in 250k miles on my VW and it’s coolant looks like new. Ive been into it three times, twice for a timing belt/water pump service and once to put a coolant heater in when it was newer. I only drained what I needed to do the job. I think today’s coolants are much better in terms of additives not falling out of suspension.

Both of my Toyotas run the pink stuff (Toyota Super Long-Life), and I have a still-sealed gallon of Ford G-05 (yellow) coolant in my garage (I ran it for several years in my ’95 F-150, replacing the original green stuff. I tried to give the G-05 to a neighbor that has an F-250 with the 6.0 PSD, but he didn’t want it – said he hated G-05. I had better luck with the G-05 in the Ford than I did with my misguided adventure running Dex-Cool in it for a couple of years.

You can run to an oreillys and get peak antifreeze thats intended for what car and the year range nicely indicated on the jugs, doesnt cost much more than the old green stuff. Too much to gamble for on these newer cars and fickle cooling systems

Unless the car’s leaking like a sieve, coolant lasts long enough, and is confusing enough, that either the dealer juice, or the correct coolant that *doesn’t* advertise itself as “universal” is the best choice.

(e.g. If your car runs Dex-Cool, aftermarket Dex-Cool is probably fine, and if you have a Euro car, the correct coolant from Pentosin is good. But “all colors” coolant should probably stay on the shelf unless it’s a heap you are getting rid of soon.)

One word of warning: More and more antifreezes are being sold pre-diluted; so make sure to check the jug before getting out your jug of distilled water.

Reminds me of the first time I took my Highlander in for an oil change. Local grease monkeys freaked out when they checked my coolant and saw my coolant was purple. (Which was a new formulation that Toyota and Lexus started using in the mid to late aughts).

I’m sure they’re 5 cents cheaper to the manufacturer than a metal one and save a whole 2 oz off the weight of the engine./s

using green silicate based antifreeze in a modern vehicle is just dumb. Silicates eventually “fall out” of solution which is why green crap needs to be changed so frequently. Anyone who’s ever “rodded” out a plugged radiator knows what happens when silicates collect on surfaces. also, they become abrasive and eventually cause water pump failure.

ever wonder why water pumps rarely fail anymore when they used to be a 3-50k mile replacement item? you no longer have all that abrasive junk in there wearing out the seals and bearings.

(man, I just don’t get the mindset of someone who thinks he “knows better” just because he thought of something or read it on the internet.)

You would be surprised, but many of the modern coolants have silicates to prolong the life. There are also some manufacturers that install silicate packs to slowly dissolve into the coolant. That’s probably the main reason for using the factory coolant.

no, I wouldn’t be surprised, because I already knew that some are hybrids. the amount of silicates in them is much lower than the old fashioned green stuff.

Use what the manual says to use and you should be good. The material selection of the metallic and rubber/plastic parts of the system goes hand-in-hand with the specification of what coolant to use. (Specifying parts of coolant systems is part of my day job.)

“(man, I just don’t get the mindset of someone who thinks he “knows better” just because he thought of something or read it on the internet.)”

If it’s on the internet, it must be true! If Sajeev says he doesn’t know, he’s not lying! If Tire Rack says the 650-14 tires on my 1962 Rambler are equivalent to today’s 195/70R14 tires,well, they must know tires! Otherwise, why are you here?

Why, there was a baseball player who had stomach pains and looked it up online, and it said he needed an appendectomy. Sure enough, the doctor he went to said the same thing!

Don’t be knocking the internet. The sum total of all human knowledge is available, plus some other stuff. It’s not all porn and cat pictures, you know. (not that there’s anything wrong with that).

The sum total of the knowledge required to select the coolant for your vehicle is available in the owners manual.

“Why, there was a baseball player who had stomach pains and looked it up online, and it said he needed an appendectomy. Sure enough, the doctor he went to said the same thing!”

yes, but you have to be learned/experienced enough to be able to filter out all of the junk out there. I mean, I know every American idiot thinks “I’m smart, so whatever I believe and whatever sounds good to me must be right” but that ain’t the case.

These days you really have to reach for the vehicle’s user’s manual to find out what the OEM recommends because there are differences between HOAT, OAT and NOAT coolants that deal with the dissimilar metals used throughout the cooling system, and you CANNOT mix them. If you mix them they can form white powdery deposits inside your cooling system.

I recently did a coolant R&R on my grand daughter’s 2012 JGC which required HOAT, so I used ZEREX G05 Concentrate, and plenty of distilled water (4 gallons) to flush and rinse the cooling system after 8 years (should have been done after 5 yrs or 100K miles, but she didn’t give it a second thought.)

Invest in an Antifreeze meter (from WalMart) if you want to get the mixture right, anywhere from 50/50 to 70/30, depending on where you live, because at least 4 quarts of clean water remain in the block after flushing and rinsing.

Just use the proper coolant for each application, mixed with only distilled or de-ionized water. It’s not difficult or expensive.

I ran a shop for a couple of years. I have a fair amount of experience with this subject. My advice is to buy exactly what the manufacturer says to. Check the part numbers. Certain manufacturers have a plethora of coolants in similar colors with similar acronyms that are completely incompatible with one another. You can ruin some mediocre pickup truck engines by using a few quarts of the coolant used in the previous year’s model, because it will turn into gook when mixed with what’s been left behind in the system.

Doing the right thing at maintenance time is easy. What about when your vehicle is a few years old and something causes it to need topping up on a Sunday to get home from the lake? Unless the outside temperature is below freezing, I would suggest topping the system with distilled water and waiting for the dealer to open to replace the coolant. If using distilled water is likely to cause the system to freeze and damage something, good luck.

Before the 2006-2010 meltdown there was an informative website, intended for professionals about vehicle cooling systems. One interesting thing was that they had a running bet; Anyone that could send them an aluminum radiator that had failed due to “electrolysis” would get a free new radiator and some $. You had to send them the failed radiator, a sample of the drained coolant, and a sample of the water used to dilute the antifreeze to 50/50%. Nobody won the bet. All the radiators sent if failed from old fashioned corrosion. At the time vehicles with leaking aluminum radiators was still a new thing for some service shops even though they had been OEM in many cars since the 1970s. After lab analysis, it was found that the water used to flush and fill the system had lots of corrosion promoting minerals in it. And, as I mentioned earlier there was water left in the block and heater system after the flush out. So the antifreeze-water mix was less than 20-30%. With the water used the anti-corrosion additives in the antifreeze were depleted quickly and corrosion set in. The places likely to leak are the radiator and heater core. The heater core was likely protected from the original antifreeze. Most are formulated to change the aluminum surface to resist corrosion. So the “new”, less than a year, radiator started leaking. So it must be “electrolysis”. Nope. Failed just like putting SAE 50 oil in a current 1.5 L turbo direct injection engine.

The Beetle’s currently sidelined with the turbo leaking profuse amounts of oil, and my new shop is full with the Jaggernaut, my Sunbeam Alpine project, and an auction ’89 Chevy Stepside.

It looks like I’ll be buying some DexCool, some G-05, and some G-40 (or I’ll just sell that turd VW). The downside is that other than green coolant and DexCool, the other coolants aren’t so common. I’ll keep hoping for a one-size fits all, but in the mean time I’ll try and clear out room in the bottom of my chemicals cabinet for a few different coolants.

This discussion reminds me of the things I read several years ago when replacing the timing belt and water pump in my 95 Accord EX. I recall reading that to use anything other than manufacturer recommended fluids was a death sentence for the car (to paraphrase). I also remember thinking the internet was full of crap and it was a cynical plot to get people to buy expensive dealer only items.

Ultimately, though, I used the recommended fluid and had the vehicle serviced at the dealer because I was young and couldn’t afford to take the gamble. I’d rather have somebody trained to fix the car do their thing than bricky car.

I always forget about the specialized chemistries and needs of certain bits, but I’m not one to question those who engineered the car. They have years of training and experience, while I just have basic knowledge and can bumble to a solution.

” I recall reading that to use anything other than manufacturer recommended fluids was a death sentence for the car (to paraphrase)”

On MotorTrend TV programs (Chan 246 on Dish) there have been several episodes I recall where the wrong fluid was used or mixed with the original spec.

One time there was a car that had two different kinds of brake fluid mixed that gave the brakes a spongy feel and grabby stops. Once drained, flushed and filled with the latest and the greatest brake fluid, all was well again.

Another time a DIY-fer mixed two different kinds of Power Steering fluid giving the feel of a delayed response when turning the steering wheel. Once drained, flushed and refilled with Dexron III, the owner could do slaloms again.

With anti-freeze/coolant the different metals now used in late model cars have different oxidation and osmosis rates, so you gotta be real careful.

I’ve become a fan of Pentosin oil products, DOT5 Brake fluid and Zerex HOAT coolant. They probably don’t work well if mixed with other original fluids but when doing a complete R&R with flush, these three fluids I have found to be the least harmful.

I’m driving a 2014 Subaru Impreza. Did some coolant research and discovered that in 2008 Subaru switched to Super Coolant, which is a sort of blue color (most guys know eight colors, like the basic Crayola box).

I snuck into the service area at the local Subaru house and talked to the mechanics. They basically said to not use anything green, then gave me a gallon of the latest and greatest.

Oh for the old days of points and condensers, of wheel bearings that have to be packed on the regular (I kid).

Aluminum Pipe 60mm

It’s important to _ASK_the counter person at your FLAPS for the undiluted coolant, it never seems to be on display and as mentioned it’s an easy way for them to essentially double their profit .

In Sunny Southern California the only place I can find distilled water under at least $1.35 is wallymart (plus you get to look and laugh at all the wallymartians) .

Another good and timely article, do your cooling system service now so you won’t be doing it in the snow when you discover your old jalopy (not everyone here has newer vehicles) has more crud in there than you realized .

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