5th gen hemi 6.4 owners need coolant oat or hoat

[v33sonata]

I’m working on my 2021 Ram 3500 6.4 HEMI, and during a tune-up I accidentally broke the plastic radiator neck with my knee. That’s what led me to pull a coolant sample, and now I’m trying to confirm whether the coolant in this truck is actually the correct Mopar purple OAT and used or something else.

The truck had the heater core replaced about 8,000 miles ago at a Canadian Dodge dealership, and I’m not familiar with whether Canadian dealers ever use a different color OAT. That’s what I’m trying to figure out before I go through the work of flushing the entire system (which I’d really like to avoid if it’s unnecessary).

Here’s what’s confusing me:

In a jar under bright light the coolant looks or orangeish.

On a paper towel it comes out pink or coral colored.

The brand-new Mopar 10-Year OAT I bought is obviously purple. I put a spot of this on a **** pad along with the one that was in the truck. You can see a side-by-side comparison in color.

Also, it should be noted which I've also included a picture of the purple coolant in the little tray is brand new from the dealership but also looks orange when it's in the 1 gallon jug which I also took a picture of.


In a glass jar I mixed the truck coolant with fresh Mopar OAT, and also mixed some yellow universal HOAT with the same Mopar OAT as a control sample. The results were similar enough that I can’t confidently say whether the coolant in the truck is pure OAT or if it was cross-contaminated at some point.

I still don't have the new radiator in as I'm waiting on hoses. Before I flush everything, I’m hoping for input from 5th-gen Ram techs or anyone who has dealt directly with OAT vs HOAT behavior in these engines.

 

[v33sonata]

And my coolant reservoir is stained pink

 

[Curmudgeon]

Hope this helps but I won't be able to answer all your question(s).

My 4th gen 2014 5.7L (can we count the differences) has a coolant reservoir that is stained pink/orange, my factory fill was replaced at the dealer about a year ago, using Mopar coolant, and it is the same orange you show at your break. I have been told the coolant is supposed to be purple out of the bottle and turns orange very quickly once in your system and used. See pic below, taken months ago for a different reason.

I don't know what to tell you about the coolant you have that is orange in the bottle. No experience with that. Basically your post went unanswered for about an hour, so this is a bit of a bump, again, see pic. Good luck.

 

[Wild one]

It uses OAT,and it doesn't matter if it's a Canuck or US truck.Ma Mopar doesn't have differant coloured coolant for differant countries,lol.That's about the right colour for OAT coolant after it's been in use for a bit.
Just for the record the only real differances between a Canuck and US truck are the daytime running lights will be enabled on a Canuck truck,and the speedometer will be in kilometers per hour instead of miles per hour.
Other then that the trucks are pretty well identical

 

[v33sonata]

Hope this helps but I won't be able to answer all your question(s).

My 4th gen 2014 5.7L (can we count the differences) has a coolant reservoir that is stained pink/orange, my factory fill was replaced at the dealer about a year ago, using Mopar coolant, and it is the same orange you show at your break. I have been told the coolant is supposed to be purple out of the bottle and turns orange very quickly once in your system and used. See pic below, taken months ago for a different reason.

I don't know what to tell you about the coolant you have that is orange in the bottle. No experience with that. Basically your post went unanswered for about an hour, so this is a bit of a bump, again, see pic. Good luck.

View attachment 575607

Thanks for your input. The one in the jug is the purple one when it's in the clear container but in the jug it shows as orange. Just like the one in the truck. Shows pink and a clear container but orange in the truck lol. Confusing

 

[v33sonata]

It uses OAT,and it doesn't matter if it's a Canuck or US truck.Ma Mopar doesn't have differant coloured coolant for differant countries,lol.That's about the right colour for OAT coolant after it's been in use for a bit.
Just for the record the only real differances between a Canuck and US truck are the daytime running lights will enabled on a Canuck truck,and the speedometer will be in kilometers per hour instead of miles per hour.
Other then that the trucks are pretty well identical

So you think I'm okay to mix the new purple one with the pink color that's in the truck now? I do know the auto lights don't turn on correctly. I was hoping that's what you were talking about lol.

 

[Wild one]

So you think I'm okay to mix the new purple one with the pink color that's in the truck now? I do know the auto lights don't turn on correctly. I was hoping that's what you were talking about lol.

The 6.4's are famous for plugging the heater core,and it wouldn't hurt to flush it ,as it sounds like it's already had 1 heater core replacement,so you might be wise to flush the engine and heater core,then look into installing a coolant filter.
Go down into the 4th Gen HD section,and you'll find a few threads on their cooling system issues, one of the fixes is flushing the system and installing a coolant filter inline with the heater hoses

 

[Wild one]

So you think I'm okay to mix the new purple one with the pink color that's in the truck now? I do know the auto lights don't turn on correctly. I was hoping that's what you were talking about lol.

Casting Sand: 6.4 Hemi HD Coolant Filter

PFA. I’ve noticed a bunch of people dealing with casting sand in their coolant that clogs up their heater core. Seems to be a big enough issue with the penstar that there’s a class action lawsuit over it. I’ve got a continuous flow of casting sand in my 2014 2500 6.4 w/140k miles I’m hoping...

www.ramforum.com

 

[Dredger]

 

[v33sonata]

View attachment 575614
View attachment 575615

This I already know

 

[Burla]

The color changes with temperature, from pink to purple and orange. No HOAT anymore for over a decade. Run rmi25 if you want to see if you have casting sand.

 

[v33sonata]

The color changes with temperature, from pink to purple and orange. No HOAT anymore for over a decade. Run rmi25 if you want to see if you have casting sand.

I guess my concern was it's very similarly colored to the hoat I went to my dealership and got a gallon of it just to compare and it's also pink in color once ona pad. I was able to call the dealership and they gave me a part number in Canada which is a OAT coolant and that's what they said they used so hopefully they did. You seem pretty knowledgeable. How should I go about flushing the system. I currently don't have the new radiator in yet. Thoughts?

 

[Burla]

You don't want to hose it out unless you have a deionized water system for a detailers car wash. And you need to remove thermostat and flush heater core separate. So you run the hose to the deionzer and then flow to where you want it flushed. RMI25 helps clear up any mistakes or any minerals that get through and keeps the system from gelling. The first time I used this I had a bronco that had slime in system from dex/iat mixter by old owner. A bunch of slime came out and then the system was fine until I sold it. I have been using it since.

If you don't use a deionzer you would be better off just filling and using RMI25 and keep checking overflow tank, it traps any contamination in system in over flow and you wet vac it out.

​

 

[Burla]

BTW, your 10 year oat is ethylene glycol the same exact thing as lifetime coolants, the coolant itself doesn't go bad. Contamination happens for many different reasons, which is the reason for flushing coolant. You have a desire to flush out old and put in new, but in many cases guys to a disservice to their truck with this type of flush. It is different for older anti freezes or dex, but we are lucky we use nearly straight ethylene glycol, unless the stuff looks like mud, it is good shape you just need the right process.

coolant thread Some SDS aren't up but the info is solid.

,

 

[Wild one]

There's theory floating around that the EGR cooler on the 6.4's breaks the coolant down faster,then it does on a non-egr 5.7,and consequently the coolant should be changed more often on a 6.4.
Whether that's true or not,i'm not sure,but i know if i owned a heavy duty truck with the 6.4,i'd probably service the cooling system every couple years,as it's a royal b!atch to change the heater core or the EGR cooler

 

[Burla]

Peak Global Life has a cult following within dyi, you can see SDS here. pdf

The main advantage to stay with Mopar 10 year is the color, once you start adding other dye's, it wont look the same. Stay with Mopar 10 is what I would do. EGR coolers can mess things up due to how hot they get. I'm guessing RMI25 is more needed in vehicles with EGR coolers. If you run it and find anything interesting like gel slime in over flow, please report back.

 

[joesstripclub]

I just added a dose of RMI25 to my truck, about 34k miles, so will see if anything gets washed up. Also added some to my 350z for fun. I changed coolant at around 100k and I'm at 130k now. I can't say I ever checked the coolant reservoir though, and I noticed a bunch of junk in it when I added the RMI25 so I need to get that cleaned up and watch to see if more accumulates in there. Fresh coolant must have done some cleaning work and I didnt realize it.

 

[Burla]

I just added a dose of RMI25 to my truck, about 34k miles, so will see if anything gets washed up. Also added some to my 350z for fun. I changed coolant at around 100k and I'm at 130k now. I can't say I ever checked the coolant reservoir though, and I noticed a bunch of junk in it when I added the RMI25 so I need to get that cleaned up and watch to see if more accumulates in there. Fresh coolant must have done some cleaning work and I didnt realize it.

post results here

If you don't clean it out it means your system is clean where ever there is flow. Plus, whether you see contaminants or not RMI 25 has benefits as well, such as rust prevention above coolant and guards against stray current from electrical system.