Asian (PHOAT) Coolant vs Prestone POAT

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I've recently been researching coolant technology and decided I wanted to try and find an affordable way to get the type of coolants the manufacturers are specifying, rather than defaulting to the 1 gallon concentrated gold-colored Prestone I've been using that claim to work for "all makes and models". I know there is quite the conversation on the topic of 2-EHA coolants, but I'm not sure how the "all-makes" Prestone gold compares to the older 2-EHA coolants. The "all-makes" gold appears to just contain ethylene glycol and diethylene glycol (and proprietary inhibitors). Is Prestone simply not publishing the chemicals for corrosion inhibitors? I think the Japanese (Asian) coolants are likely all PHOAT now, but I became confused with Prestone's POAT (not PHOAT). What did they lose in the product to make it no longer hybrid? Did they remove something that was previously inorganic, such that the HOAT became phosphated OAT now? Most of my applications are Nissan Xterra/Frontier (2000-2004). Aluminum heads, radiators, and other components, and cast iron blocks. It looked like many of the other manufacturers (Zerex, Pentosin, etc) are also likely using the exact same product base, but just changing the colors to match OEM color? Is that correct? I was confused reading a label of Pentosin Pentofrost suggesting the color was even tied to a particular year range. I don't know the OEM color of the Nissan Xterra/Frontier in 2000-2004, but I'm guessing green. I think later model Nissan (all aluminum engines) might have moved to blue. ?? I'm looking for long life coolant, and I plan to flush all the old stuff out (I rebuilt some engines and everything is new). I just need to flush out the heater cores to finish the complete flush. Also, I noticed there aren't any real concentrated versions of these newer Asian long-life coolants, other than Pentosin Pentofrost, but that stuff is so expensive you can by diluted for less than half the cost from other makers. I need some help figuring my way around all these coolants. Ugh. smile
 
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My theory is that Prestone Cor-Guard does meet the definition of a replacement coolant per Toyota's recommendation:
Quote
Toyota documentation Only use "Toyota Super Long Life Coolant" or a similar high quality ethylene glycol based non-silicate, non-amine, non-nitrite, and non-borate coolant with long-life hybrid organic acid technology.
The main fear is 2-EHA and sodium/potassium neodeconate which is the organic acid/carboxylate component in Dex-Cool and most aftermarket "universal" coolants except for PGL/Peak 10x and Final Charge. They are known plasticizers and they attack certain plastics. Toyota's pink coolant uses sebacate as the organic acid and it seems the Japanese have settled on that. It seems like Zerex is using sodium benzoate as the OAT for their Asian series of coolants. Organic acids are known plasticizers as well. The notable example of this is the stock lower intake manifold gaskets on GM's 3.1/3.4L V6s and the Vortec CSFI 4.3/5.7L truck/van engines from the mid-1990s. Dex-Cool attacked the glass-filled nylon gaskets with a silicone sealing bead around the air/water paths. The aftermarket and eventually GM released a new stainless steel gasket with fluoroelastomer seals to resist Dex-Cool. AFAIK, no Japanese engine has coolant running through the intake manifold like the Americans do - they favor dry intakes. The only places I can see Prestone Cor-Guard or "universal" coolants with 2-EHA and decoanate wreaking havoc on are head gaskets and water pump/timing cover/water bypass gaskets and RTV/FIPG on Japanese engines. The Japanese were the first to use fluoroelastomers and RTV to seal their engines. People on the forums have used Prestone or "universal" coolant without issue on Japanese engines. I would feel comfortable with Prestone Cor-Guard on a newer Japanese car, but I'd stick to OEM/CCI's GC premix for the high voltage loop on a hybrid. I'd also avoid an pHOAT or pure OAT on a older Subaru with an EJ2xx series engine unless the head gaskets were replaced with the updated OEM or Fel-Pro's PermaTorque MLS parts.
 
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And I've used PGL with no ill effects on a 2004 Fronty my adopted mom had. As long as there's no soldered brass heater core, I think Prestone Cor-Guard will work just fine. You don't have the transmission cooler issue that affected the 2007-2014 Frontys/Xterras. I ran Dex-Cool in an old Nissan Quest the parents had with no issue, I decided to flush it out and run G-05/Mercedes coolant to keep common stock with the two Benzes in the family fleet at the time. Nissan was using the old Japanese non-silicated phosphate green and switched over to blue-green pHOAT in the mid-2000s. Same stuff as Honda and Subaru. But most dealers still used silicated green and Nissan just said high-quality ethylene glycol coolant in the owner's manual.
 
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All Prestone coolant seems to have 2-EHA in it mad Instead, use Peak Global Lifetime or their new 10x coolant Or get either Zerex Asian at Walmart (red or blue)
 
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I use Pentofrost A2 (dark green) in my Nissan, as the chemistry is identical to that of the OEM fluid. Last time I bought it, I paid $25 shipped on Ebay. Sure, it's more expensive than a universal coolant, but $25 for 100,000 miles of service (my car only takes 1 gallon concentrate) is a good value in my opinion. Given a thorough flush, you can probably use just about any PHOAT if you want to maintain a compatible chemistry as the OEM. Zerex or Valvoline Asian (same thing, different brand, comes in blue and red) are two that are readily available. The Walmarts near me carry it, as do most chain parts stores. If you're adventurous, you can use whatever chemistry you think is best for your vehicle use. There's nothing about the Nissan VG engine that would favor one coolant chemistry over another AFAIK. I've never had a single issue with coolant containing 2-EHA, many OEMs use it. I think bad reputation it has of eating gaskets is overblown, which has origins dating back to GM's intake manifold fiasco.
 
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Originally Posted by nthach
My theory is that Prestone Cor-Guard does meet the definition of a replacement coolant per Toyota's recommendation:
Quote
Toyota documentation Only use "Toyota Super Long Life Coolant" or a similar high quality ethylene glycol based non-silicate, non-amine, non-nitrite, and non-borate coolant with long-life hybrid organic acid technology.
The main fear is 2-EHA and sodium/potassium neodeconate which is the organic acid/carboxylate component in Dex-Cool and most aftermarket "universal" coolants except for PGL/Peak 10x and Final Charge. They are known plasticizers and they attack certain plastics. Toyota's pink coolant uses sebacate as the organic acid and it seems the Japanese have settled on that. It seems like Zerex is using sodium benzoate as the OAT for their Asian series of coolants. Organic acids are known plasticizers as well. The notable example of this is the stock lower intake manifold gaskets on GM's 3.1/3.4L V6s and the Vortec CSFI 4.3/5.7L truck/van engines from the mid-1990s. Dex-Cool attacked the glass-filled nylon gaskets with a silicone sealing bead around the air/water paths. The aftermarket and eventually GM released a new stainless steel gasket with fluoroelastomer seals to resist Dex-Cool. AFAIK, no Japanese engine has coolant running through the intake manifold like the Americans do - they favor dry intakes. The only places I can see Prestone Cor-Guard or "universal" coolants with 2-EHA and decoanate wreaking havoc on are head gaskets and water pump/timing cover/water bypass gaskets and RTV/FIPG on Japanese engines. The Japanese were the first to use fluoroelastomers and RTV to seal their engines. People on the forums have used Prestone or "universal" coolant without issue on Japanese engines. I would feel comfortable with Prestone Cor-Guard on a newer Japanese car, but I'd stick to OEM/CCI's GC premix for the high voltage loop on a hybrid. I'd also avoid an pHOAT or pure OAT on a older Subaru with an EJ2xx series engine unless the head gaskets were replaced with the updated OEM or Fel-Pro's PermaTorque MLS parts.
Are some carboxylates more aggressive plasticizers than others? Are some carboxylates more effective corrosion inhibitors than others?
 
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Originally Posted by Brian553
Originally Posted by nthach
My theory is that Prestone Cor-Guard does meet the definition of a replacement coolant per Toyota's recommendation:
Quote
Toyota documentation Only use "Toyota Super Long Life Coolant" or a similar high quality ethylene glycol based non-silicate, non-amine, non-nitrite, and non-borate coolant with long-life hybrid organic acid technology.
The main fear is 2-EHA and sodium/potassium neodeconate which is the organic acid/carboxylate component in Dex-Cool and most aftermarket "universal" coolants except for PGL/Peak 10x and Final Charge. They are known plasticizers and they attack certain plastics. Toyota's pink coolant uses sebacate as the organic acid and it seems the Japanese have settled on that. It seems like Zerex is using sodium benzoate as the OAT for their Asian series of coolants. Organic acids are known plasticizers as well. The notable example of this is the stock lower intake manifold gaskets on GM's 3.1/3.4L V6s and the Vortec CSFI 4.3/5.7L truck/van engines from the mid-1990s. Dex-Cool attacked the glass-filled nylon gaskets with a silicone sealing bead around the air/water paths. The aftermarket and eventually GM released a new stainless steel gasket with fluoroelastomer seals to resist Dex-Cool. AFAIK, no Japanese engine has coolant running through the intake manifold like the Americans do - they favor dry intakes. The only places I can see Prestone Cor-Guard or "universal" coolants with 2-EHA and decoanate wreaking havoc on are head gaskets and water pump/timing cover/water bypass gaskets and RTV/FIPG on Japanese engines. The Japanese were the first to use fluoroelastomers and RTV to seal their engines. People on the forums have used Prestone or "universal" coolant without issue on Japanese engines. I would feel comfortable with Prestone Cor-Guard on a newer Japanese car, but I'd stick to OEM/CCI's GC premix for the high voltage loop on a hybrid. I'd also avoid an pHOAT or pure OAT on a older Subaru with an EJ2xx series engine unless the head gaskets were replaced with the updated OEM or Fel-Pro's PermaTorque MLS parts.
Are some carboxylates more aggressive plasticizers than others? Are some carboxylates more effective corrosion inhibitors than others?
Some like 2-Eha are much more aggressive than for example the Sebacic acid and Benzoic acid most European OAT/HOAT coolants use. 2-Eha is well known for its aggressive tendencies, meanwhile other OAT inhibitors like Sebacic acid and Benzoic acid ( Benzoate ) have been used by some European manufacturers for a very long time and are not particularly aggressive. There lots of different organic carboxylic acids to mention, some are more effective than others on different metals.
 
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Originally Posted by Spddm0n
I've recently been researching coolant technology and decided I wanted to try and find an affordable way to get the type of coolants the manufacturers are specifying, rather than defaulting to the 1 gallon concentrated gold-colored Prestone I've been using that claim to work for "all makes and models". I know there is quite the conversation on the topic of 2-EHA coolants, but I'm not sure how the "all-makes" Prestone gold compares to the older 2-EHA coolants. The "all-makes" gold appears to just contain ethylene glycol and diethylene glycol (and proprietary inhibitors). Is Prestone simply not publishing the chemicals for corrosion inhibitors? I think the Japanese (Asian) coolants are likely all PHOAT now, but I became confused with Prestone's POAT (not PHOAT). What did they lose in the product to make it no longer hybrid? Did they remove something that was previously inorganic, such that the HOAT became phosphated OAT now? Most of my applications are Nissan Xterra/Frontier (2000-2004). Aluminum heads, radiators, and other components, and cast iron blocks. It looked like many of the other manufacturers (Zerex, Pentosin, etc) are also likely using the exact same product base, but just changing the colors to match OEM color? Is that correct? I was confused reading a label of Pentosin Pentofrost suggesting the color was even tied to a particular year range. I don't know the OEM color of the Nissan Xterra/Frontier in 2000-2004, but I'm guessing green. I think later model Nissan (all aluminum engines) might have moved to blue. ?? I'm looking for long life coolant, and I plan to flush all the old stuff out (I rebuilt some engines and everything is new). I just need to flush out the heater cores to finish the complete flush. Also, I noticed there aren't any real concentrated versions of these newer Asian long-life coolants, other than Pentosin Pentofrost, but that stuff is so expensive you can by diluted for less than half the cost from other makers. I need some help figuring my way around all these coolants. Ugh. smile
P-OAT is just another type of HOAT, it's still a HOAT as it combines an inorganic inhibitor with an or more than one organic one. In Europe P-OAT coolants are very rare, but for example what is sometimes called Lobrid, or Si-OAT coolant are common. Lobrid means Low silicate hybrid Si-OAT means Silicate - OAT
 
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The reason why Asian PHoats are not common in Euro applications is because of the hard water considerations on the Continent. That according to a couple of Motor Magazine articles on AF types oft linked this subforum over the years. Thus uncommon to nil to find Phosphate (P) in their AF recommendations, Silicates used instead. Also the "true" Asian Phoat AFs do NOT use 2eha as inhibitor found in DexCool and the universal Dexclones including those mentioned previously. And the two Prestone AFs currently labeled for Honda (blue)and for Toyota (red) also use 2eha. Apparently Zerex G48 recommended for some Euro applications also uses 2eha as inhibitor. Otoh, according to it's SDS Zerex G-05 low silicate HOAT does not use 2eha in it's formula. Sodium Benzoate used instead. That is same inhibitor used in Peak Global Lifetime OAT no 2eha formula. To topic, if vehicle is Asian, then an Asian PHoat would be what is spec'd. Afaik currently the most readily available aftermarket Asian Phoat at low price, Valvoline/Zerex Asian AF sold at WM in either blue or red tint. The move by Nissan to blue tint (premix) nothing to do with engine block or head composition. Rather like Subaru and Toyota, just a move to longer service interval PHoat AFs. All the newer AFs backward compatible. PHOAT vs POAT, though former more common, used interchangeably. Both mean, Phosphated OAT AF.
 
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Originally Posted by FordCapriDriver
Originally Posted by Brian553
Originally Posted by nthach
My theory is that Prestone Cor-Guard does meet the definition of a replacement coolant per Toyota's recommendation:
Quote
Toyota documentation Only use "Toyota Super Long Life Coolant" or a similar high quality ethylene glycol based non-silicate, non-amine, non-nitrite, and non-borate coolant with long-life hybrid organic acid technology.
The main fear is 2-EHA and sodium/potassium neodeconate which is the organic acid/carboxylate component in Dex-Cool and most aftermarket "universal" coolants except for PGL/Peak 10x and Final Charge. They are known plasticizers and they attack certain plastics. Toyota's pink coolant uses sebacate as the organic acid and it seems the Japanese have settled on that. It seems like Zerex is using sodium benzoate as the OAT for their Asian series of coolants. Organic acids are known plasticizers as well. The notable example of this is the stock lower intake manifold gaskets on GM's 3.1/3.4L V6s and the Vortec CSFI 4.3/5.7L truck/van engines from the mid-1990s. Dex-Cool attacked the glass-filled nylon gaskets with a silicone sealing bead around the air/water paths. The aftermarket and eventually GM released a new stainless steel gasket with fluoroelastomer seals to resist Dex-Cool. AFAIK, no Japanese engine has coolant running through the intake manifold like the Americans do - they favor dry intakes. The only places I can see Prestone Cor-Guard or "universal" coolants with 2-EHA and decoanate wreaking havoc on are head gaskets and water pump/timing cover/water bypass gaskets and RTV/FIPG on Japanese engines. The Japanese were the first to use fluoroelastomers and RTV to seal their engines. People on the forums have used Prestone or "universal" coolant without issue on Japanese engines. I would feel comfortable with Prestone Cor-Guard on a newer Japanese car, but I'd stick to OEM/CCI's GC premix for the high voltage loop on a hybrid. I'd also avoid an pHOAT or pure OAT on a older Subaru with an EJ2xx series engine unless the head gaskets were replaced with the updated OEM or Fel-Pro's PermaTorque MLS parts.
Are some carboxylates more aggressive plasticizers than others? Are some carboxylates more effective corrosion inhibitors than others?
Some like 2-Eha are much more aggressive than for example the Sebacic acid and Benzoic acid most European OAT/HOAT coolants use. 2-Eha is well known for its aggressive tendencies, meanwhile other OAT inhibitors like Sebacic acid and Benzoic acid ( Benzoate ) have been used by some European manufacturers for a very long time and are not particularly aggressive. There lots of different organic carboxylic acids to mention, some are more effective than others on different metals.
Where does 2-EHA stand as a corrosion inhibitor amongst other carboxylate acids?
 
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The main reason 2-Eha is used at all is cost. It's cheaper than other OAT inhibitors, 2-Eha is pretty effective at protecting cast iron and cast aluminium, but has catastrophic results on high lead solders. Sebacic acid which is the other most common OAT inhibitor found in most OAT coolants provides very similar protection, but it's more expensive as it's made from Castor Beans, but it's much less aggressive towards solder ( if anything there is some data that it works quite well when used in combination with Silicates ) and it's not that much of a plasticiser. So coolant manufacturers will blend some of the two usually to cut down costs, others choose not to use it because of its aggressive tendencies.
 

JTK

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Originally Posted by Spddm0n
I don't know the OEM color of the Nissan Xterra/Frontier in 2000-2004, but I'm guessing green. I think later model Nissan (all aluminum engines) might have moved to blue. ??
Yeah, it's been some years since Nissan started putting blue coolant in their vehicles. I know my 2015 Versa has it. I picked up a gallon jug of Valvoline Zerex Asian Blue "with zerex technology" 50/50 ready to use juice from Walmart the other day to top up my Versa and Pathfinder's reservoir bottles. It was $12.48 for the gallon jug. crzy
 
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Originally Posted by FordCapriDriver
The main reason 2-Eha is used at all is cost. It's cheaper than other OAT inhibitors, 2-Eha is pretty effective at protecting cast iron and cast aluminium, but has catastrophic results on high lead solders. Sebacic acid which is the other most common OAT inhibitor found in most OAT coolants provides very similar protection, but it's more expensive as it's made from Castor Beans, but it's much less aggressive towards solder ( if anything there is some data that it works quite well when used in combination with Silicates ) and it's not that much of a plasticiser. So coolant manufacturers will blend some of the two usually to cut down costs, others choose not to use it because of its aggressive tendencies.
And you also have sodium benzoate, which was the choice for Mercedes and Ford until recently. Soldered heat exchangers are being replaced by crimped tube or controlled atmosphere brazing(https://blog.lucasmilhaupt.com/en-u...here-brazing-in-automotive-manufacturing) ones. Ford is using CAB heater cores on the Transit and heavy trucks are using them now. Part of rationale of why Prestone is now a pHOAT was the introduction of CAB heat exchangers. Dex-Cool and its clones is missing nitrate/nitrite. From what I understand, the mix of nitrite/nitrate and the benzotriazole/azole component of a coolant that's there to protect copper and other yellow metals is synergistic to protect leaded solder.
 
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Originally Posted by nthach
Dex-Cool and its clones is missing nitrate/nitrite. From what I understand, the mix of nitrite/nitrate and the benzotriazole/azole component of a coolant that's there to protect copper and other yellow metals is synergistic to protect leaded solder.
Any way to determine whether or not a car has a traditional soldered, CAB or crimped tube heater core?
 
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+1 Just bought 2 jugs to do the radiator hoses and thermostat on the G. It's $50+ at an Infiniti parts counter a gallon for OEM or $12.50 for Zerex Asian Blue at the Wall of China. No wonder Nissans are so expensive to own for the uninitiated.
 
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Originally Posted by AC1DD
Originally Posted by nthach
Dex-Cool and its clones is missing nitrate/nitrite. From what I understand, the mix of nitrite/nitrate and the benzotriazole/azole component of a coolant that's there to protect copper and other yellow metals is synergistic to protect leaded solder.
Any way to determine whether or not a car has a traditional soldered, CAB or crimped tube heater core?
Not really. Only way is to pull the heater core or look at the service piece. CAB is now being used by the OEMs.
 
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Originally Posted by nthach
Originally Posted by AC1DD
Originally Posted by nthach
Dex-Cool and its clones is missing nitrate/nitrite. From what I understand, the mix of nitrite/nitrate and the benzotriazole/azole component of a coolant that's there to protect copper and other yellow metals is synergistic to protect leaded solder.
Any way to determine whether or not a car has a traditional soldered, CAB or crimped tube heater core?
Not really. Only way is to pull the heater core or look at the service piece. CAB is now being used by the OEMs.
Is there typical types among time periods and countries? I have a 96 VW Golf and also a 94 Honda accord, so would the older style soldered heater cores be typical in these to cars? So if they are soldered you would want nitrates andbenzotriazole/azole to protect the leaded solder and stay away from 2eha? Which types of coolants have both those additives in it minus the 2-EHA?
 
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Originally Posted by nthach
Soldered heat exchangers are being replaced by crimped tube or controlled atmosphere brazing(https://blog.lucasmilhaupt.com/en-u...here-brazing-in-automotive-manufacturing) ones. Ford is using CAB heater cores on the Transit and heavy trucks are using them now. Part of rationale of why Prestone is now a pHOAT was the introduction of CAB heat exchangers. Dex-Cool and its clones is missing nitrate/nitrite. From what I understand, the mix of nitrite/nitrate and the benzotriazole/azole component of a coolant that's there to protect copper and other yellow metals is synergistic to protect leaded solder.
I wonder if this is why the heater core failed on our 1998 Volvo which we purchased used a few years ago. It had "enjoyed" a radiator replacement prior to our purchase which was done by a non-european specialist shop and the coolant looked to be the dexclone all make stuff. Getting to that heater core to replace it was a real nightmare involving nearly complete disassembly of the interior. The unit which came out was a classic brass-copper-solder deal. The replacement was an aluminum and plastic type similar to most modern vehicle radiators. The unit was failing at the solder joints. Of course that might have just been due to age, but blaming dexcool is always fun smile. Two years and 50k miles later the replacement unit is still working fine. I'm running Euro Valvoline/Zerex in it now.
 
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