What's better for my Cummins, OAT or HOAT?

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My 2007 Dodge Ram 2500 w/ the 6.7L Cummins diesel has 86k miles on the original coolant. I should have changed it earlier, but you know how it is. In the near future I intend to r&r the thermostat and flush the cooling system with distilled water, and then replace enough of the water with coolant to make a good 50/50 mixture. I would like to use one of the Fleetguard coolants, either ES Compleat (blue) or ES Compleat OAT (red). I understand the blue variant is an HOAT coolant, which would be similar to the factory fill. However, would a true OAT coolant be superior to HOAT?
 
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I would stick with what the OEM used from day one. I read a lot of horror stories of mixing OAT and HOAT, even small residual amounts can wreck havoc on your cooling system. Case in point on the Jeep boards if an OAT system is accidentally topped up with HOAT or vice versa they're having problems. These two coolants do not mix, and a chemical reaction will cause it to gel.
 

Joel_MD

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Originally Posted By: demarpaint
I would stick with what the OEM used from day one. I read a lot of horror stories of mixing OAT and HOAT, even small residual amounts can wreck havoc on your cooling system. Case in point on the Jeep boards if an OAT system is accidentally topped up with HOAT or vice versa they're having problems. These two coolants do not mix, and a chemical reaction will cause it to gel.
q You seem to be answering a question that I did not ask. I realize it is bad to mix IAT/OAT/HOAT types of coolant. However, I am going to flush mine completely so that is a moot point. HOAT was the factory fill on the 2007, but for model year 2013+ Chrysler began using OAT coolant in the Cummins Rams. Maybe there is a good reason to switch to the OAT variant.
 
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Is your engine a parent bore, wet sleeve, or both? If its a wet sleeve I would use final charge which is cummins factory fill on medium/heavy duty engines iirc. If it is a parent bore or sleeved parent bore like my Isuzu below than any compatible automotive coolant you like if you want to get away from factory fill. I just stuck with standard dexcool on my 7500 below when I changed a water pump a few months ago. Was going to use final charge but didnt have time to find it and factory speced dexcool works fine.
 
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I have a 13+ Cummins and just went to the dealer recently to buy some coolant to have on hand. The dealer charged me $44 for a gallon of the new OAT purple coolant. I didn't know Fleetguard had an OAT coolant. I wonder how it compares to the Mopar OAT.
 
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Originally Posted By: Joel_MD
Originally Posted By: demarpaint
I would stick with what the OEM used from day one. I read a lot of horror stories of mixing OAT and HOAT, even small residual amounts can wreck havoc on your cooling system. Case in point on the Jeep boards if an OAT system is accidentally topped up with HOAT or vice versa they're having problems. These two coolants do not mix, and a chemical reaction will cause it to gel.
q You seem to be answering a question that I did not ask. I realize it is bad to mix IAT/OAT/HOAT types of coolant. However, I am going to flush mine completely so that is a moot point. HOAT was the factory fill on the 2007, but for model year 2013+ Chrysler began using OAT coolant in the Cummins Rams. Maybe there is a good reason to switch to the OAT variant.
I was sharing info, I didn't realize you knew of the nightmares of accidental mixing, maybe another member will benefit. My advise still stands though. There are people who thought they completely flushed out their cooling systems and had problems because they didn't get it all out. As far as the change I heard rumors for why, but I don't know for certain.
 
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Joel_MD

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Originally Posted By: 3311
Is your engine a parent bore, wet sleeve, or both? If its a wet sleeve I would use final charge which is cummins factory fill on medium/heavy duty engines iirc. If it is a parent bore or sleeved parent bore like my Isuzu below than any compatible automotive coolant you like if you want to get away from factory fill. I just stuck with standard dexcool on my 7500 below when I changed a water pump a few months ago. Was going to use final charge but didnt have time to find it and factory speced dexcool works fine.
All the Cummins engines have bored cylinders. That is one of the advantages of the Cummins over the Ford Powerstroke; none of those cavitation corrosion issues. What is "final charge?"
 

Joel_MD

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Originally Posted By: Rendezvous
I have a 13+ Cummins and just went to the dealer recently to buy some coolant to have on hand. The dealer charged me $44 for a gallon of the new OAT purple coolant. I didn't know Fleetguard had an OAT coolant. I wonder how it compares to the Mopar OAT.
The Fleetguard OAT is expensive too; around $130 for a case of four gallons. I'm getting the feeling that OAT is the way to go if I'm doing a full flush of the system. Thanks for the advice.
 
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Originally Posted By: Joel_MD
Originally Posted By: 3311
Is your engine a parent bore, wet sleeve, or both? If its a wet sleeve I would use final charge which is cummins factory fill on medium/heavy duty engines iirc. If it is a parent bore or sleeved parent bore like my Isuzu below than any compatible automotive coolant you like if you want to get away from factory fill. I just stuck with standard dexcool on my 7500 below when I changed a water pump a few months ago. Was going to use final charge but didnt have time to find it and factory speced dexcool works fine.
All the Cummins engines have bored cylinders. That is one of the advantages of the Cummins over the Ford Powerstroke; none of those cavitation corrosion issues. What is "final charge?"
http://www.peakhd.com/product-lines/Final-Charge/ Good Stuff!! I believe IIRC, that it is the same as PowerCool?
 
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Originally Posted By: Joel_MD
Originally Posted By: 3311
Is your engine a parent bore, wet sleeve, or both? If its a wet sleeve I would use final charge which is cummins factory fill on medium/heavy duty engines iirc. If it is a parent bore or sleeved parent bore like my Isuzu below than any compatible automotive coolant you like if you want to get away from factory fill. I just stuck with standard dexcool on my 7500 below when I changed a water pump a few months ago. Was going to use final charge but didnt have time to find it and factory speced dexcool works fine.
All the Cummins engines have bored cylinders. That is one of the advantages of the Cummins over the Ford Powerstroke; none of those cavitation corrosion issues. What is "final charge?"
Both Cummins and the Powerstrokes are parent bore engines. The pre powerstroke 7.3 IDI was an over bored 6.9 so it had thinner cylinder walls and was prone to cavitation. I would go with an OAT coolant though in your truck. They last longer than hoat and being silicate free means the water pump seals and bearings last longer. Final Charge would be a good choice though in my opinion. It meets the cummins 14603 spec for seal compatibility and from what I see is much cheaper than fleetguard oat.
 
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From the article: Update: November 2012 Chrysler Switches to New Coolant for Model Year 2013 Though Chrysler has used G-05 HOAT low-silicate formula coolant for over a decade, it is changing formulas for model year 2013. The new coolant will be a straight OAT type coolant, dyed orange, but it is NOT Dex-Cool (which GM uses). The new Chrysler OAT coolant will NOT contain 2-EHA (2-ethylhexanoate) which can soften gaskets and seals that contain silicone. The service life of the new coolant will be 10 years or 150,000 miles, which ever comes first, and it will be the factory fill coolant for all cars and light trucks.
 

Joel_MD

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Originally Posted By: Y_K
Just a reference point, not an answer. Wrong board, of course. Still, may find it somewhat useful. Good luck. on a sidenote, as an MD you should take it for granted, when patients answer a wrong question.
Interesting article, but the "MD" in my username refers to the state in which I live, not my education.
 
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The biggest difference between HOATs, Japanese OATs containing phosphates and OAT's containing 2-EHA (dex cool) inhibitors is that silicates and phosphates are fast acting and the protective layer re-forms very quickly, while 2-EHA takes a long time (could be thousands of miles) to lay down the inhibitors. So, for engine experiencing severe cavitation problems, fast acting inhibitors are best, for everything else slow acting inhibitors will be fine.
 
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I'm still going to recommend Rotella Ultra ELC once again. One of the highest oxidation states in the business, $20-23 a gallon, fill and forget. Meets all Cummins specs.
 

Joel_MD

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Originally Posted By: DoubleWasp
I'm still going to recommend Rotella Ultra ELC once again. One of the highest oxidation states in the business, $20-23 a gallon, fill and forget. Meets all Cummins specs.
I looked at the Rotella ELC products on the Shell website. It looks like they're equivalent to the Peak Final Charge or Fleetguard ES Compleat coolants. Where do you find them for $20/gallon? Are you talking about the 50/50 mix? I see some online stores selling the concentrate for $31/gal plus shipping, or six gallons for $165.
 
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