[HWYSTR455]

Originally, antifreeze was green so people knew it was caustic. That's it. It's only when they went to the newer formulas that different colors came out, and it basically was only for the 'transitional period' of the new formulas.


.

[78w72]

All colors are not the same, there are definitely worries mixing some coolant types/colors according to experts & reputable auto fluid companies. Just doing a google search will show all kinds of current warnings not from the early 2000s... 9 out of 10 say its best to not mix coolants, or at least know for sure what type is in the vehicle you are considering mixing another type with. Some very new types claim they are compatible with all makes & models but still a good idea to know what you have before mixing.

Your call on what you believe but I prefer to stick with what reputable companies & many mechanics say, manufacturers dont usually say to only use their brand, but they do suggest using the right type... my newer 4runner uses a red color coolant that has low or no certain additives that other types may have... i can use any brand but has to be the red type like valvoline zerex for asain cars, i would never mix or use the old traditional green stuff I use in my classic pontiacs.

https://www.valvolineglobal.com/en-e...n%20your%20car.

https://www.google.com/search?q=DOES...client=gws-wiz

[Formulabruce]

I will just drop this here..

[HWYSTR455]

Ok, so there's IAT, OAT, NOAT, and HOAT coolants. The 'old' 'green' coolant is IAT, and was phased out by 2001.

IAT is 'inorganic' coolant.

OAT is 'organic acid' coolant.

NOAT is 'nitrited organic' acid.

HOAT is 'hybrid organic' acid. It's a mix of IAT & OAT.

Hybrid came out in 2002, and is the mainstay used today.

Interestingly enough, I looked, and there is some what is called IAT 'original formula' stuff out there, but the info I was looking at was still from 2006. The ones that 'say' 'original formula' I doubt are true IAT coolants, pretty sure EPA killed it, but there's no marking on the containers that tell you.

This is the 2006 article reviewed in 2014, still not current info:

https://www.hemmings.com/stories/201...-of-antifreeze

GMB talks about colors, IAT & OAT, but there's no date on the info:

https://gmb.net/blog/inorganic-vs-organic-coolants/

No date on the Valvoline article posted before, pretty sure it's also outdated info. "according to experts, it is best not to mix different coolant colors - just for safety."

As for mixing, yes, back in the day it was a no-no to mix IAT & OAT, with no real reason given.

Even NAPA doesn't give any specific or scientific reason why not to mix:

https://knowhow.napaonline.com/what-...-need-to-know/

Prestone says that mixing IAT & OAT can turn to gel, that's about as specific as it gets, but it's still vague:

https://www.holtsauto.com/prestone/n...ixing-coolant/

They don't even touch on the other types in the article.

There's also what's called POAT, but from the sounds of it, it's actually a HOAT.

https://www.autoserviceworld.com/job...rrect-coolant/

I'm still thinking you can't get 'true' IAT anymore, it's all a hybrid I bet. But one thing is for sure, you can't tell by the color.

Satisfied?


.

[MIke L]

So, I guess the bottom line is if you don’t know what is in your engine, the most prudent thing to do is NOT just drain and fill as some do.

Just do a complete flush and start over because what is left in the block may not be compatible to what you’re gonna add.

That is my dilemma




Mike

[78w72]

Was just saying its best to not just willy nilly mix all colors nor are all colors the same as was mentioned. Im sure you can mix them but its not recommended, its not going to cause an explosion or instantly ruin the cooling system, but there are reasons they make different kinds/colors and for the most part there is no benefit to mixing them, its not just manufacturers want you to buy their brand.

Highly unlikely valvoline has outdated 20 year old info on their FAQ section. Every other link searching google is current info & most say to not mix it.

The toyota red type has no silicates, some other types do, I see no reason to experiment mixing other types.

The "old" green stuff phased out in 2001 is not what most people consider the traditional green stuff thats been in use for 22-23 years now.

Everyone is free to do what they like, most prefer to follow what the manufacturer recommends for most auto fluids, but there are modern universal fluids that meet specs for many different makes, even some newer coolants that make that claim.
I do use other fluids like valvoline maxlife ATF in my toyota that calls for toyota WS fluid, but many years after the WS came out companies have formulated universal ATF's to meet & exceed the specs of WS and other vehicles, maxlife, amsoil, redline etc, i use maxlife in my th350/400 transmissions too, it meets the same requirement as dex3 but is a modern synthetic formulation priced low & easy to find.

[Formulajones]

Originally Posted by MIke L

So, I guess the bottom line is if you don’t know what is in your engine, the most prudent thing to do is NOT just drain and fill as some do.

Just do a complete flush and start over because what is left in the block may not be compatible to what you’re gonna add.

That is my dilemma




Mike

Mike, I've had my classic vehicles for decades and have been through all of them so they've all had the standard green stuff. So for me it's just been a simple drain and refill.

In a case like yours where you aren't sure what might be in it, I'd probably flush it all out. But I personally won't use a harsh chemical flush. If I have one I have to completely drain, I'll pull the block plugs, remove the thermostat, run the engine and stick the garden hose in the radiator until I see clear water running out of the block. Shut it down, drain everything and refill with 50/50 green stuff and call it good. From there service is easy every few years.

[HWYSTR455]

I think a drain, fill w water, drain and fill would be fine if you're not sure.

If you're on a fresh build, that's your line in the sand and just go newer stuff.


EDIT: Pretty sure the 'flush' stuff neutralizes the additives and acids.


.

[MIke L]

Thanks Fellas for your reply’s!

I know it’s been over 8 yrs since since it was drained and refilled.
It has a light green tint and I tested it using one of those hand held tester’s and the pointer just barely moves up.
I live in SW Florida so freeze protection isn’t a concern.

Thanks Again


Mike

[HWYSTR455]

Freezing may not be a concern, but coolant becomes acidic, and eats stuff. Water pumps, Intake gaskets, divider plates, divider plate sleeves & gaskets, even head gaskets can become compromised.





.

[MIke L]

Yep
You’re exactly right
Comin out in the morning

Thanks again guys




Mike

[Schurkey]

Originally Posted by HWYSTR455

I think a drain, fill w water, drain and fill would be fine if you're not sure.

As long as the "drain" includes pulling the block drain plugs, otherwise you'll have a gallon of water trapped in the block.

[Ram Air IV Jack]

Originally Posted by Schurkey

As long as the "drain" includes pulling the block drain plugs, otherwise you'll have a gallon of water trapped in the block.

I used to think that too until I read my 69-service manual which says to raise the rearend up about 12 inches and you will drain most of the block. I've tried this and it worked great with no mess!

[mgarblik]

I had a feeling that when the discussion turned to the different coolants, things would swerve out of control pretty fast. Imagine having to teach this stuff and provide accurate information to students that is reliable for a number of years? Nearly impossible. I feel HWYSTR455 probably provides the best overall recommendation although other posts have good info as well. To me, the OE's who drive the aftermarket products, completely screwed up the coolant deal. I blame GM specifically because they were the first outlier, having to come up with their own coolant, Dexcool, to cover up their head gasket issues which were killing the O2 sensors and not enabling their feeble engines to pass the long term emissions tests. That's what really started the entire mess with changing coolant formulas and a there was the added benefit of longer service intervals. The OE's gave the excuse it was for corrosion benefits, but that was really just BS. Aluminum engine parts were functioning fine in engines for 80 years before Dexcool.
Color of coolant has no meaning at all now. It's the chemistry that matters. The color is personal preference. When I closed my fleet shop 1 year ago, I kept 9 different coolant formulas in stock. Problem was, when a vehicle came in, what the heck is in there since color is no indication? We recommended a complete flush if we didn't know what was in the vehicle. Second choice was to top off with the universal stuff. If you know what's in the system, we recommend going to the OE dealer and getting the correct coolant from the parts department. Surprisingly, OE coolant only cost a couple bucks more per gallon than unknown, possibly incorrect stuff. It's a real mess.

[78w72]

The only issue I had was with the statement that said " all colors are the same stuff these days", they definitely are not the same supported by the list of 4 or 5 different types. All I was saying is that its probably not a good idea to mix different types/colors unless they specifically say they are compatible with each other. All the info I found on that subject is recent and from mostly reputable sources.

Ive never used dexcool in classic cars nor tried to mix different types/colors, always the traditional green stuff, whether that be the original IAT back in the 70s/80s/90's or the current green most people refer to when mentioning traditional green stuff.

When I look at coolants, most all state what years & vehicles they are for, such as valvoline zyrex for asain cars that is the correct red stuff that toyota calls for, i use that in my 4runner since it was quite a bit cheaper priced at walmart than the toyota brand from a dealership.

[MatthewKlein]

Originally Posted by mgarblik

I had a feeling that when the discussion turned to the different coolants, things would swerve out of control pretty fast.

I blame GM specifically because they were the first outlier, having to come up with their own coolant, Dexcool, to cover up their head gasket issues which were killing the O2 sensors and not enabling their feeble engines to pass the long term emissions tests.

That's what really started the entire mess with changing coolant formulas and a there was the added benefit of longer service intervals. The OE's gave the excuse it was for corrosion benefits, but that was really just BS. Aluminum engine parts were functioning fine in engines for 80 years before Dexcool.


Color of coolant has no meaning at all now. It's the chemistry that matters. The color is personal preference. When I closed my fleet shop 1 year ago, I kept 9 different coolant formulas in stock. Problem was, when a vehicle came in, what the heck is in there since color is no indication? We recommended a complete flush if we didn't know what was in the vehicle. Second choice was to top off with the universal stuff. If you know what's in the system, we recommend going to the OE dealer and getting the correct coolant from the parts department. Surprisingly, OE coolant only cost a couple bucks more per gallon than unknown, possibly incorrect stuff. It's a real mess.

Hadn't heard Dexcool was supposed to help with head gaskets, that's news to me.

When engines began using more aluminum parts we definitely started seeing erosion of the aluminum. Sometimes it would be bad enough to plug the heater core or cause a gasket leak. That seems to have largely gone away now that they have the coolant better formulated.

We also stock multiple different types of coolant for foreign cars. I can't mess it up if I used the factory recommended coolant.

[HWYSTR455]

I've been looking for the SAE codes and if coolant actually has a code(s). I see a lot of SAE docs regarding standards, but no code listing, only types.

I see no type listing for IAT type coolants, only HOAT, especially for the green stuff.

Here's another doc that has coolant info, but again, no listings for IAT coolants, only hybrid and others based on service end of life.

https://penriteoil.com.au/assets/pdf...5/Coolants.pdf

Here's a category of coolants on the SAE website, but wow, it's a rabbit hole, and would take some digging/research/homework to go through it all. Again, no specific code listings.

https://www.sae.org/standards/content/j814_202305/

There are standards for gaskets & seals compatible with type of coolants, again, no straight IAT listings.

I only have some motorcycle coolant which is certified/recommended by KTM, and it has a statement on the label saying 'meets of exceeds ASTM D3306, D6210, and D4985'. Maybe when I get a chance tomorrow I will dig on those numbers, but 'ASTM' looks like an SAE number to me.

I still think there is no straight IAT formulas available for automotive/motorcycle use, but have not confirmed that. I can't imagine manufacturers going 'backwards' when engineering coolant formulas, especially since the EPA at one time did come out and specifically state the use of IAT had an end of life in use.

When searching the SAE website for 'ASTM D3306', many docs/hits come up, 2660 to be exact. This will take an effort.

https://www.sae.org/search/?qt=ASTM+D3306

If there are any autistics here, please, feel free, and share your findings.


.

[Mister Pontiac]

Just to stir the pot... who else runs only pure distilled water?

Heh.

[Singleton]

Originally Posted by Mister Pontiac

Just to stir the pot... who else runs only pure distilled water?

Heh.

Right here, I change it out every six months. No worries about freezing temps here

[67GTONUT]

Originally Posted by Mister Pontiac

Just to stir the pot... who else runs only pure distilled water?

Heh.

Pretty close to it...... and I live in the NE.
I run a very light concentration of Zerex G-05, get freezing point low enough to be comfortable. Car is in garage that never drops below 40 degrees