The US Army's Search for a Universal Extended Life Coolant Specification

[X15]

I recently stumbled across some very interesting coolant research that directly pertains to some of the discussions that have been taking place here recently, I've attempted to summarize it:

Currently the US Army is using conventional green Inorganic Acid Technology (IAT) coolant with Supplemental Coolant Additive (SCA) and changing it annually instead of testing and recharging it. This is obviously quite expensive and wasteful, so they decided to look at moving to an Extended Life Coolant (ELC) that would be suitable for all the numerous different vehicles the Army fields.

They started by looking at all the engines used in ground vehicles and equipment, and what the manufacturers recommended ELC is:

https://apps.dtic.mil/sti/citations/AD1114771


Along side that they conducted a commercial market survey of available ELCs and their properties:

https://apps.dtic.mil/sti/citations/AD1112055


Five ELCs were selected for testing along side the existing conventional coolant; two that use straight Organic Acid Technology (OAT), two Hybrid OATs (HOAT), and one Nitrited OAT (NOAT).

All six were then subjected to laboratory bench and simulated service testing:

https://apps.dtic.mil/sti/citations/AD1170629


The commercial coolants were anonymized for confidentiality, but there's enough information present in the report to determine which is which:

Sample ID #	Product	Type	Color	Inorganic Additives
FL-18023-20	Cummins ES Compleat	HOAT	Blue	Borate, Phosphate, Silicate, Nitrate, Nitrite and Molybdate
FL-18024-20	Final Charge Global OAT Extended Life Coolant	OAT	Red	Nitrates, Molybdates
FL-18030-20	Conventional CID A-A-52624	IAT	Green	Nitrate, Nitrite, Borate, Silicate
FL-18031-20	John Deere Cool-Gard II	HOAT	Orange	Borate, Phosphate, Molybdate, Nitrate, and Silicate
FL-18071-20	Cat ELC	NOAT	Strawberry Red	Nitrites, Molybdates
FL-18072-20	Cummins ES Compleat	OAT	Red	Nitrates, Molybdates

The goal was not just to find a single coolant and select it for exclusive use, but to develop a specification that multiple products can be qualified as meeting. They want said specification to cover both light and heavy duty engines, so compatibility with cast aluminum parts commonly found in light duty engines is critical. And to make things harder qualified coolants must also be compatible with each other so they can be freely mixed in the field.

Therefor compatibility testing was under taken by mixing samples of each possible combination of the six candidates at ratios of 30/70, 50/50, and 70/30.

These blends were then subjected to ASTM D4340 testing for compatibility with cast aluminum alloys under heat-rejecting conditions; A cast aluminum test specimen with an alloy typical of that used in cylinder heads is exposed to coolant with salt (NaCl) added to it at a temperature of 135 °C (275 °F) and pressure of 193 kPa (28 psi) for one week. After which it's cleaned and measured to determine how much, if any, weight it lost, and what its condition is. The coolant is examined for its appearance and pH, and checked for the presence of any solids/precipitates.

The coolants they looked at generally claimed to be able to be safely mixed with other products, however of the 30 blends they tested 17 of them produced "large, white, jelly-fish like precipitates" and had heat-transfer corrosion rates above the allowable 1 mg per cm2 per week!



These precipitates were analyzed with a number of different methods including Scanning Electron Microscopy (SEM):



Energy Dispersive Spectroscopy (EDS) found the presence of aluminum in the precipitates, which did not come from the coolants.

The two OATs and the NOAT were the exception, they did not form any precipitates when mixed with each other. The rest of the testing on the precipitates was inconclusive.

There are a few other interesting tidbits in the report:

• OATs are noted to have very slightly higher thermal conductivity, potentially leading to very *slightly* increased cooling system efficiency, which could give a tiny increase in fuel economy.
• The engine OEMs they spoke to collectively agreed that 2-EHA is harmful should not be allowed.
• The OEMs additionally agreed that OAT coolant was the best fit for the Army's needs, NOAT was rejected for not being safe for use with aluminum.

The two OAT coolants were selected to progress to real world testing as they were determined to be the most universal, it will be interesting to see how they do!

 

[97K15004WD]

Interesting studies. Thank you for posting these!

 

[97K15004WD]

Looks like OAT is the best so far, such that they were downselected for further study.

"The only mixtures that produced no precipitates were the two OAT candidates when blended
together, and the two OAT candidates when each were mixed with the one NOAT candidate. This
could mean that OATs and NOATs are able to be mixed with less risk, however, reasons below
will elaborate on why a NOAT is not recommended for Military applications."

"Based on both OEM testimony, as well as the lack of precipitates formed in the ASTM D4340
Compatibility Study from WD 002, it was decided to move forward with the two OAT based
coolants in WD 006: CL21-6187 (FL-18024-20) and CL21-6187 (FL-18072-20)."

 

[SC Maintenance]

Interesting data - great post.

The two OAT coolants were selected to progress to real world testing as they were determined to be the most universal, it will be interesting to see how they do!

My understanding is that all the universal coolants like Prestone are OAT's because they mix with everything and work to some degree with everything - so no real surprise out of this actually.

 

[doitmyself]

Great article. Thank you. Things I found interesting:
- The military is still using IAT coolants with SCA.
- My John Deere Coolgard II is yellow, not orange like in the test.
- The article says engine mfg. recommend against 2EHA. Seems to me that BITOGers have been more forgiving about it.

 

[SC Maintenance]

- The article says engine mfg. recommend against 2EHA. Seems to me that BITOGers have been more forgiving about it.

I learned about why to not use 2EHA on this board ?

 

[doitmyself]

I learned about why to not use 2EHA on this board ?

Maybe I am wrong, but I get the impression that BITOGERS know that 2EHA can be bad, with the decades old GM gaskets failures cited years ago as maybe attributed to 2EHA and air intrusion. But, it seems that people here discount the current possible effects of 2EHA by saying that modern engines have components (gaskets, etc.) that are 2EHA safe, so it is a non-problem.

Doesn't the popular Prestone All Makes-All Models coolant contain 2EHA (confirm, please) and many BITOGers consider it a non-problem?

EDIT: Yep, looks like Prestone does contain 2EHA

https://prestone.com/wp-content/uploads/2020/11/SDS508-Universal-RTU.pdf

https://prestone.com/wp-content/uploads/2021/09/SDS862.pdf

 

[hrv]

You know the joke in the military always was .....watch out for military grade or specs.....

 

[SC Maintenance]

Maybe I am wrong, but I get the impression that BITOGERS know that 2EHA can be bad, with the decades old GM gaskets failures cited years ago as maybe attributed to 2EHA and air intrusion. But, it seems that people here discount the current possible effects of 2EHA by saying that modern engines have components (gaskets, etc.) that are 2EHA safe, so it is a non-problem.

Doesn't the popular Prestone All Makes-All Models coolant contain 2EHA (confirm, please) and many BITOGers consider it a non-problem?

EDIT: Yep, looks like Prestone does contain 2EHA

https://prestone.com/wp-content/uploads/2020/11/SDS508-Universal-RTU.pdf

https://prestone.com/wp-content/uploads/2021/09/SDS862.pdf

I have seen many posts on this board that point out certain coolants contain 2EHA. Whether someone wants to use them is up to them.

2EHA will soften certain plastics and Silicon. Which ones and whether your engine might have some is up to you. In theory they should not. I have spent a career fixing stuff in the field that in theory is impossible to happen.

 

[RooflessVW]

You know the joke in the military always was .....watch out for military grade or specs.....

Which I never understood, because there is not a single ounce of mechanical sympathy in the military.

In that context, I'd say even the "junk" holds up pretty well.

 

[doitmyself]

I agree with you SC Maintenance, have similar lifetime experiences, and I also avoid 2EHA like the plague. Heck, some years ago one of our workplace tractor diesel engines was ruined from cavitation because the oaf put regular car antifreeze in it, not knowing that wet sleeve engines required different coolant.

Again, my point was that many here seem to discount the possible effects of 2EHA and it was interesting to me that the research paper pointed out their OEM equipment mfg. recommend against it.

You and I are on the same page.

 

[PWMDMD]

Right...As if the US Army doesn't have an "agenda". You can't trust anything these days. Probably funded by penny pinching federal government accountants.

 

[JHZR2]

These blends were then subjected to ASTM D4340 testing for compatibility with cast aluminum alloys under heat-rejecting conditions; A cast aluminum test specimen with an alloy typical of that used in cylinder heads is exposed to coolant with salt (NaCl) added to it at a temperature of 135 °C (275 °F) and pressure of 193 kPa (28 psi) for one week. After which it's cleaned and measured to determine how much, if any, weight it lost, and what its condition is. The coolant is examined for its appearance and pH, and checked for the presence of any solids/precipitates.

The coolants they looked at generally claimed to be able to be safely mixed with other products, however of the 30 blends they tested 17 of them produced "large, white, jelly-fish like precipitates" and had heat-transfer corrosion rates above the allowable 1 mg per cm2 per week!

I’m not sure what is unexpected here. And frankly, the in service engineers at GVSC should be aware of the chemical phenomena already.

Mix oat with a silicated chemistry? We’ve known for 25 years now what happens. This is no different than the Dex sludge phenomena when folks would top up with mixed chemistry.

And old school IAT with SCA isn’t exactly the “best of” stabilized silicated coolants. The practice of draining and dumping is indeed wasteful. And the chemistry may not even align with the coolants the OEMs are running with these days.

I find the other accelerated test also a bit odd. I get the elevated temperatures and pressures, but the addition of all that salt? Not that relevant other than some USMC scenarios. I get it if that’s the ASTM prescription though…

But I’m not sent anything unexpected here. A non2-EHA OAT has now been long proven to work well in various situations.

 

[97K15004WD]

I find the other accelerated test also a bit odd. I get the elevated temperatures and pressures, but the addition of all that salt? Not that relevant other than some USMC scenarios. I get it if that’s the ASTM prescription though…

Sometimes all you have is saltwater to use. Desalinated is used for the troops to drink and the engines are not the priority.

Just like "BDAR" and "Battle Overide". Some situations dictate the prioritization of personnel over equipment.

 

[X15]

Interesting data - great post.



My understanding is that all the universal coolants like Prestone are OAT's because they mix with everything and work to some degree with everything - so no real surprise out of this actually.

Thanks.

In this case they are considered "universal" because they can be used in both light and heavy duty engines, and can be mixed with other non-hybrid OATs.

The report found that mixing them with IAT or Hybrid OATs caused accelerated corrosion and the formation of cooling system passage clogging precipitates.

 

[X15]

Great article. Thank you. Things I found interesting:
- The military is still using IAT coolants with SCA.
- My John Deere Coolgard II is yellow, not orange like in the test.
- The article says engine mfg. recommend against 2EHA. Seems to me that BITOGers have been more forgiving about it.

The John Deere Cool-Gard II looked pretty orange to me when I was working out what coolant was what sample id #.



I meant to go back and double check the color... I see it's listed as "gold" or "golden" in Safety Data Sheets.

 

[X15]

I’m not sure what is unexpected here. And frankly, the in service engineers at GVSC should be aware of the chemical phenomena already.

Mix oat with a silicated chemistry? We’ve known for 25 years now what happens. This is no different than the Dex sludge phenomena when folks would top up with mixed chemistry.

But I’m not sent anything unexpected here. A non2-EHA OAT has now been long proven to work well in various situations.

They are generally required to test, verify, and state the obvious, regardless of common wisdom or prior knowledge.

In this case though the initial survey of the commercial coolant market specifically asked about compatibility issues:

"8. Has any compatibility testing been done on the product(s) with other ELC products? What sort of testing? Are there any ELC products that are incompatible with your product(s)?"

The response was summarized as:

"In terms of compatibility, the general trend was that there are no known compatibility issues when mixing ELC with other ELC or conventional coolant, however, most companies recommended that their product not be diluted by more than 20% - 25% of another type of coolant. This will decrease the performance of the coolant."

So expected or not, the test results certainly did not line up with the responses they received.

I find the other accelerated test also a bit odd. I get the elevated temperatures and pressures, but the addition of all that salt? Not that relevant other than some USMC scenarios. I get it if that’s the ASTM prescription though…

I agree that it's quite a bit of salt!

Presumably the results have been found to representative of longer term testing without any added contaminants, I can't imagine the test would still be in use if it was completely misleading. ASTM do note that "Additional, more comprehensive evaluations with simulated service, dynamometer, and vehicle tests should be used to establish the long-term effectiveness of the coolant."

 

[JHZR2]

The John Deere Cool-Gard II looked pretty orange to me when I was working out what coolant was what sample id #.

View attachment 156053

I meant to go back and double check the color... I see it's listed as "gold" or "golden" in Safety Data Sheets.

It’s definitely a pleasant gold. Just changed my 350sd over and it’s the same color as the funnel essentially.

 

[nthach]

Maybe I am wrong, but I get the impression that BITOGERS know that 2EHA can be bad, with the decades old GM gaskets failures cited years ago as maybe attributed to 2EHA and air intrusion. But, it seems that people here discount the current possible effects of 2EHA by saying that modern engines have components (gaskets, etc.) that are 2EHA safe, so it is a non-problem.

Doesn't the popular Prestone All Makes-All Models coolant contain 2EHA (confirm, please) and many BITOGers consider it a non-problem?

EDIT: Yep, looks like Prestone does contain 2EHA

https://prestone.com/wp-content/uploads/2020/11/SDS508-Universal-RTU.pdf

https://prestone.com/wp-content/uploads/2021/09/SDS862.pdf

Prestone does make a non-2-EH version of Cor-Guard as their Command series. And supposedly it’s Cummins certified. Can’t find it locally, it’s a unicorn coolant. It’s this stuff: https://prestone.com/product/presto...itrite-free-extended-life-antifreeze-coolant/

Peak’s Final Charge Pro-Series pHOAT is also 2-EH free, but no Cummins certification.

It seems like Cummins has the same reservations on 2-EHA as the Japanese, Cummins also uses RTV as a sealant. But it also seems RTV is as common in diesels as in Japanese cars - doesn’t Navistar want a special Wacker Chemie RTV on the T444E/Ford PSD 7.3L and Ford calls for their TA-357 on the 6.0-6.7L PSD?

 

[nthach]

I have seen many posts on this board that point out certain coolants contain 2EHA. Whether someone wants to use them is up to them.

2EHA will soften certain plastics and Silicon. Which ones and whether your engine might have some is up to you. In theory they should not. I have spent a career fixing stuff in the field that in theory is impossible to happen.

AFAIK, it’s nylon and silicone that are the most susceptible to 2-EHA damaging them(see: GM LIM gaskets) but radiators use PA66/GF33 tanks. BMWs do have their coolant reservoirs fail, the G-48 coolant used for the last 30 years in those is a 2-EHA SiHOAT.

Now, Permatex claims their latest RTVs(Optimum and Right Stuff) is “resistant to post-Dex-Cool modern coolants” but that be meaningless. The solution to contain 2-EHA is FKM fluoropolymer per 3M and Fel-Pro seems to agree as it’s their preferred elastomer for the problem child GM engines with Dex-Cool.