Coolant flush
06-17-2020, 06:09 PM
#1
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Coolant flush
Recently bought a 2016 Willy's Wheeler and I'm in the process of servicing the fluids. Has 44k miles so I'd just like to do all the fluids now and write down the mileage to start fresh with everything. I've done everything except gear oil and coolant. I had some questions about a coolant flush on the JK because I've read conflicting information. I know Jeep recommends using Mopar OAT antifreeze on 2013+ JK models. My question is can I swap to a different 50/50 antifreeze if I flush the system with distilled water? I've read that you can and can't do this so if anyone's done a coolant service or flush I'd appreciate some feedback.
Another quick question about a flush. If I do go the route of flushing the system with distilled water, draining the system only gets half the fluid out. So, I saw someone say that on the last flush, you add concentrated coolant to the system and you would have a 50/50 mix since half the system has just water in it. Is this accurate for flush purposes only and adding 50/50 to top off the reservoir?
Another quick question about a flush. If I do go the route of flushing the system with distilled water, draining the system only gets half the fluid out. So, I saw someone say that on the last flush, you add concentrated coolant to the system and you would have a 50/50 mix since half the system has just water in it. Is this accurate for flush purposes only and adding 50/50 to top off the reservoir?
06-17-2020, 07:20 PM
#2
JK Junkie
If you flushed out all the coolant, I don't think there is anything incompatible in the cooling system with HOAT or the other types. But no one is going to guarantee that, especially since it might take over a decade to find out something was incompatible. Also, it's a pain to get it completely flushed out -- Many iterations of filling with DI water and draining. Why do you want to switch antifreeze types, and what do you want to switch to?
Regarding the flush & fill: Look up the coolant system capacity with the 3.6L, and see how much comes out when draining it. That will tell you about how much remains, and you can figure it out. I've done what you suggest once on my 3.8L and there was just enough room for adding pure anti-freeze for roughly a 50/50 mix. Similar to you, this was an initial flush that I wanted to spend some extra time and money on.
Auto parts stores will have some inexpensive hydrometer-type antifreeze concentration gauges. They work based on the specific gravity changing as ethylene glycol percentage is increased. Handy to have...
Regarding the flush & fill: Look up the coolant system capacity with the 3.6L, and see how much comes out when draining it. That will tell you about how much remains, and you can figure it out. I've done what you suggest once on my 3.8L and there was just enough room for adding pure anti-freeze for roughly a 50/50 mix. Similar to you, this was an initial flush that I wanted to spend some extra time and money on.
Auto parts stores will have some inexpensive hydrometer-type antifreeze concentration gauges. They work based on the specific gravity changing as ethylene glycol percentage is increased. Handy to have...
Last edited by Mr.T; 06-17-2020 at 07:39 PM.
06-18-2020, 04:58 AM
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The only reason I would want to switch coolant is to have something that I could buy from my local auto parts store since they don't have Mopar on hand. I'd prefer to not wait on shipping or go to a dealer in the event that I need antifreeze. Also, other brands are less expensive and do the same job. Thanks for the suggestion with looking up how much comes out when you drain it and the antifreeze concentration gauge. I didn't know such a gauge existed so I am definitely going to look into that.
06-18-2020, 05:08 AM
#4
JK Jedi
The Mopar coolant really doesn't cost that much more than high-quality stuff at the parts stores, but I do understand the issue if you don't have a dealer close by. I usually keep 2 gallons on hand anyhow, but part of that is just my normal fluid stash for serious wheeling trips like Moab where you can be out in the middle of a three trail day and not have anything around. The real issue with trying to do a complete flush is being 100% confident you have everything out of the heater core as well, so if you do that it will just be a longer process of cycles so you can make sure you've run distilled through the HC as well. If you're 100% certain you've flushed everything out, there's no issue then using whatever you want.......at least that's my understanding from a lot of reading. I just stuck with Mopar OAT myself.
btw, our petcocks suck and are worthless. Plan on pulling the lower hose to drain.
btw, our petcocks suck and are worthless. Plan on pulling the lower hose to drain.
06-18-2020, 05:14 AM
#5
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Another thing to consider here with these coolants is that the factory coolant is rated for 7yr/150k miles on the new stuff (13+?) and 5yr/100k on the old stuff (07-12ish).
06-18-2020, 08:05 AM
#6
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Having a couple extra gallons on hand is probably what I'm going to go with instead of swapping coolants. That's also very disappointing to hear about the petcock, makes the job way easier.
06-18-2020, 09:15 AM
#7
Super Moderator
The petcock only takes 1/4 turn but it's plastic and so is the housing. It goes south quickly. I haven't pulled it on my new radiator, but I do keep an extra one in my toolbox in case this one gets deformed.