POAT vs IAT coolant: Engine-specific application and differences

[Slow Car Sport Mode]

So, This thread is intended to be about engine specific applications of POAT coolant perhaps replacing the conventional IAT coolant... like, specifically, Either if a car came with it already, or if the cooling system was being completely refilled after being empty and flushed.

In my specific and exact case I'm asking in regards to a Subaru EJ 251 engine. I only have one specific part left to buy, I've received good advice about break-in oil, I could either ask again or research how to use said oil, And I have 2 different types of coolant I can select from from my stash to provide the mechanic to refill the car. I have 3 gallons pre-mix POAT; I still have a decent amount of IAT. Obviously coolant is something you refill once and forget about until every couple of years. It doesn't disappear by itself unless something is wrong.

So, in my instance, I literally need to select from giving him this...

Or this. (Constant relabeling but. It is the same)

Which one? And why?

Oh, and.. let us please (edited out the praying hands) keep this topic discussing about the question asked. Some posters - staff included! - seem to feel the need to respond.. but not actually anything about the question asked.. and directed "towards the poster." Let's have none of that. Hopefully, this can be avoided, and if seen.. dealt with, by management. Thank you! That should keep it on topic.

 

[kschachn]

Isn't this essentially the same question?

What are the true dangers in using non OEM coolants?

I don’t believe the DEXcool thing was ever that significant in reality. The hyped up drama surrounding it was big 4 sure. Anyway 2-eha is still wildly used. Being poured into everything with wheels and universal coolants for years now by millions of folks having no idea that 2-eha exists. No...

bobistheoilguy.com

 

[Slow Car Sport Mode]

Isn't this essentially the same question?

What are the true dangers in using non OEM coolants?

I don’t believe the DEXcool thing was ever that significant in reality. The hyped up drama surrounding it was big 4 sure. Anyway 2-eha is still wildly used. Being poured into everything with wheels and universal coolants for years now by millions of folks having no idea that 2-eha exists. No...

bobistheoilguy.com

No, it is not.

Now what do you have to add about the topic?

 

[kschachn]

No, it is not.

Now what do you have to add about the topic?

I'll wait for the thread to evolve.

 

[4WD]

I'll wait for the thread to evolve.

Or not

 

[dnewton3]

Isn't this essentially the same question?

What are the true dangers in using non OEM coolants?

I don’t believe the DEXcool thing was ever that significant in reality. The hyped up drama surrounding it was big 4 sure. Anyway 2-eha is still wildly used. Being poured into everything with wheels and universal coolants for years now by millions of folks having no idea that 2-eha exists. No...

bobistheoilguy.com

The "same" question? No.
Incredibly similar question? Yes.

No, it is not.

Now what do you have to add about the topic?

SCSM - don't be coy. You'll catch more flies with honey than vinegar.



On topic: are you intending to just have the mechanic do a drain/fill? Or a complete system fluid replacement? It's not clear to me which you intend to do.
- If a drain/fill, then use whatever the OE fluid is compatible with
- If a whole system is a total fluid exchange, then I'd go with the All Vehicle stuff

 

[KrisZ]

Since it’s Prestone products, these are all OAT coolants the last time I looked into their coolants.

All their “formulas” be it Asian, European, domestic show 2-ethylhexanoic acid (2-EHA), which is OAT.

 

[OVERKILL]

The "same" question? No.
Incredibly similar question? Yes.



SCSM - don't be coy. You'll catch more flies with honey than vinegar.



On topic: are you intending to just have the mechanic do a drain/fill? Or a complete system fluid replacement? It's not clear to me which you intend to do.
- If a drain/fill, then use whatever the OE fluid is compatible with
- If a whole system is a total fluid exchange, then I'd go with the All Vehicle stuff

He blew his engine up (#3), is buying a new shortblock instead of scrapping the vehicle and he has a massive stash of coolant that he acquired at some point, so he's trying to figure out if he can/should use this, or not, in this application.

 

[Slow Car Sport Mode]

The "same" question? No.
Incredibly similar question? Yes.



SCSM - don't be coy. You'll catch more flies with honey than vinegar.



On topic: are you intending to just have the mechanic do a drain/fill? Or a complete system fluid replacement? It's not clear to me which you intend to do.
- If a drain/fill, then use whatever the OE fluid is compatible with
- If a whole system is a total fluid exchange, then I'd go with the All Vehicle stuff

So, my situation is that I'm turning a short block into a complete engine. Or perhaps more accurately DIFY is. The 4 mechanics at the shop are performing the work there.

Part of the process of putting a new engine back in is they at least blow air through the heater core. I assume that in this case that is the only part that will actually get flushed, Because I'm literally getting a remanufactured "enhanced" short block That is supposed to address all the known issues of an EJ251 mated to reconditioned heads Is sold through a Subaru dealership. So whatever one you feel that falls into about either a drain and fill or a total flush I'm not sure.

Aside from the concerns about 2EHA chemical, I am concerned about whether the POAT or the IAT would perform better in the engine. This is also where I intend this thread to be a general question about changing coolancts in different engines, if you will.

It somewhat sounds like you're saying to just go with the all mix and models and not worry about the POAT And again that answer is for my specific application although this thread is about if you can essentially change coolants in different engines.

He blew his engine up (#3), is buying a new shortblock instead of scrapping the vehicle (hence reference to staff commenting on wisdom, or lack thereof, of the decision making process) and he has a massive stash of coolant that he bought at some point during a procurement binge, so he's trying to figure out if he can/should use this, or not, in this application.

OK so @OVERKILL Just responded to the thread addressing a poster and not really addressing the thread so I hope he can be dealt with accordingly.

OK so @OVERKILL Felt the need to interject irrelevant information and specifically about the pulster so I hope he can be dealt with accordingly.

Since it’s Prestone products, these are all OAT coolants the last time I looked into their coolants.

All their “formulas” be it Asian, European, domestic show 2-ethylhexanoic acid (2-EHA), which is OAT.

@KrisZ you're saying their main AMAM is also OAT? You actually make a really good point I could look on the back of it and see. I'll double check when I get home.

 

[KrisZ]

None of the coolants you listed are POAT or IAT, they are all OAT. So your concern is non existent.

As far as changing formulas, yes you can do it if you flush the whole system with distilled water. Within reason of course. Something really old would probably not take too well to Dexcool for example due to old, incompatible gaskets.

I’ve successfully changed from Asian POAT that uses phosphates to Zerex G-05 POAT that uses silicates for example.

 

[SC Maintenance]

Since it’s Prestone products, these are all OAT coolants the last time I looked into their coolants.

All their “formulas” be it Asian, European, domestic show 2-ethylhexanoic acid (2-EHA), which is OAT.

^^^ What they said. Same why - its got 2-EHA. Its an old school OAT. Much better stuff out there.

 

[Slow Car Sport Mode]

None of the coolants you listed are POAT or IAT, they are all OAT. So your concern is non existent.

As far as changing formulas, yes you can do it if you flush the whole system with distilled water. Within reason of course. Something really old would probably not take too well to Dexcool for example due to old, incompatible gaskets.

I’ve successfully changed from Asian POAT that uses phosphates to Zerex G-05 POAT that uses silicates for example.

Just want to say that the one coolant the Asian one.. it's specifically says it is POAT on the back That's one of the things that started this whole thread.

Then there is of course we wanted to select the best possible coolant for this build so that this brand new engine lasts a long time. Basically the best possible cooling system performance.

I'll snap a pic of the back of it when I get home because I'm telling you I really thought these coolants are different chemistries.

Let us know tomorrow.

@kschachn ?? I definitely don't understand this post and I'm almost home to update that packaging picture.

OK the first 4 are the green cap one

The next 3 are the black cap one

This is why.. for filling the system up 100% new and assuming a flushed radiator and heater core (the only two components that will remain).. for my application, which one would you select?

I only have 3 of the green cap one. One of my main concerns is if the mechanic could use those, and my system would be OK.

Or are they EXACTLY the same as the black cap ones. In which case.. again, use?

@SwampSurvivor DIFY means Do It For You.

@KrisZ Well if it's all the same stuff then I'll just send the 3 bottles over and be confident my cooling system got refilled with the right stuff then. Want to make sure the coolant is correct. Seems like it's fine.

Thank you!

And I don't think talking about "#3" is relevant background info at all, @OVERKILL . Only that I have a pre-existing stash of coolant.

 

[kschachn]

Let us know tomorrow.

 

[KrisZ]

Again, they are all the same formula. The bottle never mentions it is POAT or other, just says it’s compatible.

 

[cptbarkey]

Stick with one or the other, it doesnt matter as long as its the same.

If I were in your shoes I would be much more OCD about the folks working on your engine:
1) Are they experienced with Subaru engines.
2) the head gaskets are MLS and not some cheap ebay or amazon knockoffs.
3) they are using Aisin or better quality items for the timing/water pump system.

Finally: if i were the mechanics I would be highly annoyed being dictated fluids from the customer, but thats just me. Tread carefully.

 

[dnewton3]

SCSM -
Thanks for the update regarding shortblock.

This is the way I see the topic specific to your question(s) ... Hopefully I've got the whole picture now ...

IMO, this is not an issue of the coolant being compatible with the rebuilt engine; either one would be perfectly fine. The only concern would be the two coolants being compatible with each other, however that's not an issue because you're doing a full system fill (new engine). This is, at its core, essentially a factory-fill approach.

In short, I'd say pick the one that's gonna have enough volume (in your stash) to do the job, and don't worry about it. You shouldn't have to worry about coolant for another 10 years minimum.

 

[Slow Car Sport Mode]

Two part reply. First is for my application.

Part 1:
I think I've found the coolant to use for my application.

SOA868V9210 - Factory fill long life coolant - Genuine Subaru Part

Genuine Subaru Part # SOA868V9210 - Factory fill long life coolant

parts.subaru.com

Here is an article about coolant "and what makes Subaru coolant different" from a Subaru board. https://automotivetechinfo.com/wp-content/uploads/2005/11/What-Subaru-Antifreeze-Should-I-Use.pdf

So, apparently Subaru coolant part number SOA868V9210 has following "ingredients:"

@Trav also I have been told by the Subaru board that the Subaru Blue coolant "Now contains 2EHA."

And now to Part Two of the reply: NOT for my application.

Part Two:

My concern now is about if 2EHA is harmful or not. I was talking with a member off the board and the question (which I believe I asked earlier...not sure) came up.. "I'd go OE on coolant." Very next thought, on both our parts: "Unless OE coolant also contains 2EHA."

I asked the question on a brand-specific board and it would appear this particular coolant (I am curious if it is the green now) does NOT have the 2EHA; the smaller, newer, blue "Super coolant" may have 2EHA.

SO the whole Part Two of my reply, and a new question for this thread since "All the Prestone I have is the same" (and I've long suspected that, just never known for certain. Tricky labeling, in my opinion).... is.. "How bad is 2EHA?"

Perhaps another thread for IAT vs. OAT/POAT/HOAT coolant, unless even if the Subaru coolant I just posted is an OAT. The G-05 that is (now) in the Taurus is an OAT. So let's please turn this into an information-heavy clarification session, and no it's not just 100% about my upcoming application https://sunwestautoinc.com/product/subaru-ej25-short-block-2-5l-sohc-1999-2005/ (of everything but the heater core has been replaced for the new Short Block meets Heads and other things to make Long Block in Subaru, thus why not use THE MOST OPTIMAL coolant) but more a general question about the types of coolants, as per title.
^ The coolant being asked here what is best to put in is going in that.

And now the 2EHA concern.

"How bad is 2EHA?"
*Also: Subaru coolant mentions an "Organic corrosion inhibitor."

Item is HaZmat

Unlike aftermarket coolants containing borates and silicates that harm aluminum and cause blockages, this coolant is specifically formulated for use with aluminum alloy Subaru engines and water-cooling systems.
• Protects against corrosion with organic corrosion inhibitor
• Eliminates the silicate gelling that causes radiator plugging/overheating
• Meets/exceeds all Subaru OEM specifications
• Required for use in all warranty repairs

Protects against corrosion with organic corrosion inhibitor

 

[SC Maintenance]

If you find a answer on 2EHA let me know. I have looked long and its sort of a circular argument.

2EHA is supposedly a pretty good anti corrosion additive, and its also pretty inexpensive hence its popularity. It can soften some silicone and some plastics.

In theory your car wouldn't have these types of plastic or silicone. My question is how would you know, especially on something older.

My perspective is why take the risk, when there are good coolants out there without it?

I also know that Nissan "long life Green" and Nissan "long life Blue" - both HOAT's don't have any 2EHA. So in my Nissan's I don't use anything with 2EHA. In fact I stick with OEM for those - its not a lot more money.

 

[KrisZ]

Let me clarify for the OP if I can.
First:

The G-05 that is (now) in the Taurus is an OAT.

No it is not. It is HOAT.


Forget about IAT coolants, the have no been used since 90s and they are not worth getting.

OAT stand for Organic Acid Technology.
HOAT stands for Hybrid Organic Acid Technology.
PHOAT stands for Phosphate Hybrid Organic Technology.

All these coolants need something to control cavitation.
OAT use 2EHA for it.
HOAT use silicates
PHOT use Phosphates.

As far as I know, all Asian makes use PHOAT coolants, so you have nothing to worry about 2EHA. Same goes for HOAT.
HOAT and PHOAT coolants do not use 2EHA, period.

 

[SC Maintenance]

How do you tell if its a HOAT or a PHOAT. This is the Nissan Green. It doesn't mention phosphate anywhere, but it doesn't say its not either. Blue is the same