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Cumminsblake
11-18-2019, 03:39 AM
I have a 2012 rubicon, itís just starting to cool down around here in Houston.

The other week I got the check engine light for the thermostat stuck open, the Jeep wouldnít warm up to dead center.

Replaced the thermostat today no big deal. I went to autozone for coolant. I read up on the Hoat coolant for a 2012. Unfortunately I must have read an old thread stating that the Hoat coolant bottles have a blue cap so I bought the Prestonís long life with the blue cap.

I drained out some coolant during my thermostat replacement and it was pink / red.

The new coolant I put in was lime green.

I start up the Jeep and get it to temperature the new thermostat works. Iím sitting in the Jeep with the heater on and noticed that the driver side isnít blowing as hot as the passenger side.

I start googling on the forums and some folks attribute that issue to the wrong coolant.

Can someone give me their .02 here?
I realize I need HOAT coolant. I put in Prestone (green) extended life.

Should I flush the whole Jeep and ensure I put in the HOAT coolant? Does anyone think that will remedy the issue of the driver side and passenger side blowing different temps?

Bustedback
11-18-2019, 03:58 AM
You should probably flush the wrong coolant out and replace it with the HOAT coolant. The wrong stuff can be acidic and cause some serious problems.


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jeeeep
11-18-2019, 04:54 AM
I have a 2012 rubicon, itís just starting to cool down around here in Houston.

The new coolant I put in was lime green.

I start up the Jeep and get it to temperature the new thermostat works. Iím sitting in the Jeep with the heater on and noticed that the driver side isnít blowing as hot as the passenger side.

I start googling on the forums and some folks attribute that issue to the wrong coolant.

Can someone give me their .02 here?
I realize I need HOAT coolant. I put in Prestone (green) extended life.

Should I flush the whole Jeep and ensure I put in the HOAT coolant? Does anyone think that will remedy the issue of the driver side and passenger side blowing different temps?

1. check the prestone site for compatibility, I have prestone in 2010 that I used to top off after a thermostat change and have had no issues but Prestone listed it as compatible with my system.
If not compatible, flush out the entire system and use the correct anti-freeze.

2. a flush should remedy the temperature difference but be sure to reverse flush the heater coil separately so any crap that's flowing thru it doesn't get clogged again.
If it were me and the Prestone I used is compatible, I would just flush the heater core. There are several youtube videos on how to flush the heater core, it's quick and easy enough to do.

DeJkUnlimited
11-18-2019, 05:07 AM
My 2013 had the same issue. Ultimately I had to have the heater core replaced. I back flushed it several times, would get satisfactory heat for an hour or two only to get clogged again and the same symptoms would return. Apparently at one point with the earlier 3.6L engines in the JK they had an issue with casting sand from either the heads or the block circulating through the cooling system which has a tendency to clog the heater core which most commonly affects the driver side heat. Often times you can see sediment in the bottom of your coolant overflow reservoir. Whatever winds up being your cause, it’s critical to use the proper OEM coolant or compatible coolant. If you put the wrong stuff in it can be catastrophic to your engine and entire cooling system. If you call the dealer parts dept and give them your VIN they can tell you which coolant your Jeep uses. It’s either OAT or HOAT and they cannot be inter-mixed.