Switching Over From IAT to OAT Coolant in 2001 Dodge Ram?

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I've been down the rabbit hole a bit looking at coolant stuff, and haven't found a clean answer. I am currently building an engine for my 2001 Dodge Ram that of course originally came with IAT green coolant. For the extended service interval, I would prefer to switch it over to the new Mopar OAT purple 10 year coolant. Since the engine is being completely rebuilt, that means all the gaskets and seals will be completely new (mostly aftermarket fel-pro), as well as the water pump and hoses. I put a new Denso radiator in about 2 years ago. Am I good to go in terms of using the newer OAT stuff in this instance? I've read stories about the OAT coolants potentially causing gasket/seal failures in older cars designed for IAT coolant, but it's unclear to me whether that was 2-EHA related or not exactly. I know that compound has been removed from most modern OAT coolant formulas.
 

Msmith68w

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Just to clarify, I'm not looking to mix with the IAT coolant at all. I plan to drain and flush the radiator/heater core, and obviously the block is completely drained and flushed during the rebuild process so it will have no residual coolant.
 
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You would be fine filling it with the purple Mopar coolant if you want. If it was mine I'd just fill it with long life Prestone or Peak. I'm converting everything I have over to prestone 10yr/300k as they need coolant changes. $12 a gallon for full strength at walmart.
 

Msmith68w

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Didn't Chrysler start using G05 HOAT coolant in 2001? You could use that. It's superior to conventional green and is a 5 year coolant.
I don't know what year they did that exactly. Eventually they switched to a Purple OAT 10 year in the 2010s somewhere.

My 01 ram has always had green IAT coolant in it.
 
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Personally I would run the HOAT (G-05) in it instead of the OAT. The HOAT will begin protecting the metals it comes into contact with almost immediately, whereas it takes the OAT around 5K miles to kick into gear and start protecting unprotected metal surfaces.
 

Msmith68w

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G-05 HOAT is what is recommended by Chrysler for this old truck at this point, so I may end up going that route. I was just thinking that 1. The purple is a distinctive color so it will not be mistaken for other coolants. 2. I could get the 10 year service life on the new purple coolant. and 3. I could standardize all my cars (new and old mopars) to the same purple coolant instead of having several different kinds.

I do see that HOAT is supposedly better at corrosion resistance for iron and aluminum (the 5.9 is iron block/heads and wet aluminum intake), but Mopar is running the purpose stuff in the new hemis which are iron block and aluminum head so....surely it's fine.
 
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If you have other vehicles already using the OAT, go with OAT to make things easier. The G-05 is more expensive and harder to find in emergencies anyway.

One of my Hemi’s spec’d HOAT and the other OAT, despite being virtually identical in every way except year of manufacture. I’ve switched both over to OAT (Dexclone) for simplicity’s sake though…that and the economy of it makes more sense for me.
 
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Just to clarify, I'm not looking to mix with the IAT coolant at all. I plan to drain and flush the radiator/heater core, and obviously the block is completely drained and flushed during the rebuild process so it will have no residual coolant.
The mentioned coolants will, work for any engine /coolant system.
 

Msmith68w

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If you have other vehicles already using the OAT, go with OAT to make things easier. The G-05 is more expensive and harder to find in emergencies anyway.

One of my Hemi’s spec’d HOAT and the other OAT, despite being virtually identical in every way except year of manufacture. I’ve switched both over to OAT (Dexclone) for simplicity’s sake though…that and the economy of it makes more sense for me.
Alright.

I've read about Chrysler putting some sort of slow release silica packets in the reservoir tanks on the vehicles with the purple OAT coolant. Is that something I would want to do with this old truck when putting it together you think?

And I agree, the purple is easy to find and fairly affordable. G-05 on the other hand is more expensive and more difficult to find.
 
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Alright.

I've read about Chrysler putting some sort of slow release silica packets in the reservoir tanks on the vehicles with the purple OAT coolant. Is that something I would want to do with this old truck when putting it together you think?

And I agree, the purple is easy to find and fairly affordable. G-05 on the other hand is more expensive and more difficult to find.

I’m not aware of any silica supplements for the OAT cooling systems. Given its extraordinary service life, I would just pour and go.
 

Msmith68w

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I'm seeing some reports of heater core clogs and other such gelling issues with that Mopar OAT coolant. I'm aware that it was common that techs in like 2013-2014 were topping off HOAT filled vehicles with OAT and that caused issues, but these new accounts appear to be claiming clogging issues with straight OAT factory fills. Have you seen any of this?

It's making me reconsider a little bit. That and the OAT's lower corrosion resistance compared to HOAT.
 
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I haven’t seen anyone complaining of issues with the Mopar OAT, but my Mopar interactions have been mostly limited to the LX car forums.

Even still, hard to imagine the coolant itself causing clogs in the system while still within its service life. Once it’s outside its service life, sure, or if it were mixed with really hard water during fill, but the factory fill OAT is mixed with distilled water and shouldn’t be causing any problems.
 

Msmith68w

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Alright cool. I always do distilled water as well.

I really like the idea of standardization and the 10 year service interval. I'm really good about a lot of maintenance stuff, but I tend to neglect the coolant changes a bit.
 
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