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Discussion Starter #1
Hi,

I noticed today that my coolant level is a bit too low on my 2015 GC 5.7.

The manual says to only use OAT coolant, with Chrysler standard.

I have a bottle of Audi Coolant, pink (same color so, but I know color means nothing), with TL 774F standard.

I did a little search and I found out that TL 774F seems to be OAT.

Can I use it for topping my coolant level?
 

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If it was HOAT or IAT, I'd say no way.... A quick google search says the TL 774F is European G12, which indeed is OAT.... ...but not the Chrysler OAT (they're keeping it secret so they can overcharge for it at the Dealership)... ...so I don't really know if it will mix well or not... ...likely it will.... ....see if there is anything about G12 mixed with Dexcool having any problems... ...people are saying, but I don't see any proof, that Ford's and FCA's OAT is just GM Dexcool....
 

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How low is it? You can get away by adding a bit of distilled water.
 

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Actually HOAT and OAT is very tolerant of the minerals in tap water. That was part of developing the long life anti-freezes. People weren't changing anti-freeze when they should, and if they did or if they topped off, they used tap water and not distilled water.

So they set out to develop and anti-freeze that lasted longer and works better with tap water in regions that have a lot of minerals in their tap water (i.e. hard water). It doesn't protect as well as the original IAT, but it protects better if you're a dumb vehicle owner that won't change his anti-freeze when its needed and will use tap water instead of distilled water.

Having said that, it's still better to use distilled water than tap water, even with HOAT and OAT.
 

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Discussion Starter #5
Thanks for your ansewer,

My coolant level was 1 cm (0,4 inch) higher than the low mark.

So I added about 0,3 literl (10 oz) of distilled water and now i'm just 2cm (0,8 inch) lower than the max mark, so I guess my level is good, I don't want to add to much as it's only water.

I hope I wont have corrosion or freezing problems because I added this water, but I think it's ok because the coolant capacity is 14,6 liters, so the 0,4 liters I added represents about 2,2% of the content, so if it was good for -37°C before, now it should still be good for about -36°C.

BTW i was surprised of the cap of the coolant bottle in the car trunk. In my previous cars, it was a very tightened cap and in this car, it's just a "clipped" cap, same as for the windshield washer fluid... So I guess if coolant was lacking, it's because it evapored because of the crappy cap... I even wonder how this cap isn't popping out with the coolant pressure...

BTW, i'm a newbie but, if coolant evaporates, is it only water which evaporates, or the OAT is evaporating too? Because if only water evaporates, adding only water won't matter.
 

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On my 2011 V8, the proper coolant level when cold is the coolant on or just above min, and it will rise to or just above max when the coolant is hot. I filled it to max while cold, and when hot the level went high enough that it vented out the overflow port. I was a convinced I had a leak because I added coolant several days in a row and it always dropped the next day, to I saw it dripping out of the overflow port on the ground. I was overfilled it everyday and it was venting.

The cooling system has a pressure cap that maintains a higher pressure on the cooling system, to prevent the coolant from boiling over, years ago it was 16PSI, today most are 18PSI. The coolant also expands and contracts when hot or cold and there has to be room for that....

That is where the overflow tank comes in, when the coolant heats up and expands, it forces it way past the pressure cap and goes through the tube to be captured in the overflow tank. The pressure cap has a 2nd reverse valve in it. So when the coolant cools off and contracts it forms a vacuum in the system, which will suck coolant out of the overflow tank through that 2nd reverse valve. That is why I said you need to take the pressure cap off the radiator (ONLY WHEN THE ENGINE IS COLD) and check the fluid level in the radiator. If you have a leak in the system, it might suck air back in from the leak instead of coolant back in from the overflow tank. So the level in the overflow bottle doesn't tell what the true level in cooling system, but only if the system is operating perfectly.....

Some vehicles have a slightly different cooling system that gets rid of the overflow tank and instead has an reservoir that is part of the pressurized cooling system. These tanks must be stronger to withstand the pressure and have the pressure cap on them instead of the radiator. So as the coolant expands and contracts with heating and cooling it just flows up or back from the reservoir.

So if you had other vehicles that had a stronger tank with a cap that was difficult to remove, it was probably that latter system I described, you were removing the pressure relief type valve that was also the cap. Your WK is the other system, the pressure relief valve cap is on the radiator, the cap on the overflow tank is just to keep dirt and dust out....

You should be only losing a few ounces a year to evaporation. I don't know if its just the water that evaporates out of the mixture or if some of the anti-freeze or corrosion prevention package that evaporates also...
 

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Discussion Starter #7
Thanks for your reassuring and very complete answer :)

Like you, my coolant level when cold was at min and rises at max when hot. I thought the max level on the bottle was the level to have when cold, so I added a bit of distilled water. I'll see if when hot it gets vented out of the overflow port too... And if not, for sure I won't add more.

Didn't know there were different systems for the radiator and bottle cap. Right, my previous cars (BMW, Audi, VW) had the other system with a pressurized coolant bottle and a very solid plastic cap that had to be turned about 20 times before being removed. That's why I was wondering about the small cap on my WK2.

I just hope the 10oz I of water I added didn't diluted too much the coolant and make it freeze the winter, but I don't think because there is a lot of coolant so 10 oz probably won't matter. 50/50 it's ok up to -37°C, here we have, for the worse winters, about -20°C so now it's probably still ok for -30°C
 

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Actually FCA had the same reservoir cooling system as the BWM, Audi and VW on their LX vehicles for a few years. Probably the same time all these companies were owned by the same group..... The U.S. Chrysler LX platform had a problem with the reservoir bottle cracking and needing replaced...

So FCA on their American vehicles have seem to go back to the overflow bottle, no stress on the bottle since its outside the pressurized system, the system vents into the overflow bottle or sucks it back via the vacuum that forms when the coolant contracts....

The reservoir system keeps air in the reservoir that connect by a tube to the system and the reservoir is at the highest point so the air stays in the reservoir, the air gets compressed to allow expansion and contraction of the coolant.

You always want the pressure relief cap at the highest point of the pressurized system, so any air in the system gets vented before the coolant, so the reservoir system has to have that plastic bottle higher than the rest of the cooling system with the pressure cap on it. The overflow bottle system, the pressure cap has to be at the highest point on the cooing system, usually the radiator, but some cars the highest point is not the radiator and pressure cap is somewhere on the engine. But the overflow bottle can be anywhere, just connected by a tube to the pressure cap. So you also have more flexibility with the overflow bottle system, some cars have their overflow bottles in the fender.....
 

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So Peak Anti-Freeze is implying they have an aftermarket equivalent for FCA's OAT antifreeze....
219854

OET NORTH AMERICAN VEHICLE COOLANT EXTENDED LIFE ORANGE

OET NORTH AMERICAN VEHICLE COOLANT EXTENDED LIFE ORANGE is Formulated For:
Chrysler: 2013 and newer
Ford: 2011 and newer
GM: 1995 and newer

While Peak is not as bad as Prestone or others, that their marketing is outright deceptive IMO, I've seen Peak also market anti-freeze without making clear what it is, so I don't know if I trust them that much... ...Only Zerex (subsidiary of Valvoline) have I've seen be consistently honest with their marketing and labeling, I would trust them and I do not see them marketing an antifreeze as a replacement for FCA's OAT as of yet.....

But if Peak is being honest, then yes, FCA's OAT is just GM's Dexcool.......
 

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Zerex G30
I had looked on Zerex's website, but it more than a few months ago and couldn't find it....

It lists for applicability:
  • Chrysler(R) 2013-Present
  • Dodge(R) 2014-Present
  • Jeep(R) 2014-Present
  • Ford(R) Trucks and SUV's 2013-Present
  • Ford(R) Passenger Cars 2012-Present
  • General Motors(R) 1997-Present
Which like the Peak product, corresponds with that its GM Dexcool, just purple...
But I find Zerex much more trust worthy than the other aftermarket Company's, and its Purple to boot....
Thanks for the find!
 

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No O-Reilly's near me... ....haven't looked in a few months, but back then it did seem hard to find outside of O'Reily's....
219878
 

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For all the things that I've read about that can happen when different types of coolants are mixed together, I think I would just go to the dealer and buy a gallon of genuine Mopar OAT coolant, especially if it's still under warranty.
 

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For all the things that I've read about that can happen when different types of coolants are mixed together, I think I would just go to the dealer and buy a gallon of genuine Mopar OAT coolant, especially if it's still under warranty.
That would be the safest course of action, I'm frustrated that FCA won't tell us what exactly their OAT antifreeze is or what's in it, but at the same time, do you trust an aftermarket that imply's their Dexcool product is the same as Fords and Chrysler/FCA's OAT antifreezes, when this same aftermarket has been selling their Dexcool in a jug that doesn't tell you what it is, and labels it to imply its an universal antifreeze, but the fine print tells you that you need drain and thoroughly flush the system if you want to use it for more than top-off????

I'm still not convinced Ford and FCA's OAT antifreeze is simply GM's Dexcool, but its certainly possible... ...the fact no one has come out and directly said that is also telling.... ....you might note, they say you can use their OAT with all these vehicles, not that its the same as the Manufacturer's OAT....

And if I had a new vehicle that used the Manufacturer's OAT, I would be tempted to just drain and thoroughly flush it, till there was no trace of the original antifreeze, and switch to Zerex G-05.... ....I am convinced that OAT has a lot of drawbacks, the only thing in the positive column for it is that it lasts even longer than HOAT..... ...the effort to drain and flush HOAT 50k miles earlier, pales in comparison to the cost and effort to fix the problems that might arise from OAT.....
 
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