What's Harder On Modern Coolant... Time Or Miles?

My 2015 Jeep Grand Cherokee only has 16,000 miles on it. It's still running the original coolant. It's going to be a LONG time before that vehicle ever sees 100K miles. (Which is supposedly how long the coolant lasts).

So... When should I start thinking about changing the coolant? How long does coolant last before it starts going "bad"? Is this newer stuff that great compared to the older yellow / green Prestone?

That's what my 1991 F-150 runs, and I've changed that coolant every 2 years. It's still running the original 31 year old heater core. And the radiator is close to 25 years old. So I must be doing something right.

My gut feeling is to change it out. But it's going to be a bit of a PITA to do it. It's not easy getting to the drain plug. And just looking at You Tube videos on the subject, there is talk about, "bleeding the air from the system"... (5.7 HEMI V-8)... Something I've never done on any vehicle after a coolant change. The air always seems to work it's way out of the system after a few heat / cool down sessions.

Where is a good place to buy this newer coolant besides the dealer? They rape you on everything. Or should I let it go for a while? It's been in there for 7 years.
I changed coolants in two family vehicles. One was 13 and the other 17 years in service. Both looked new. Visible cooling system were spotless. I asked myself- why am I doing this? My experience only. YMMV as they say
 
This guy performs a coolant flush on a 2014 HEMI Grand Cherokee. While he's a bit long winded, and is using the wrong coolant, you can see starting at the 16:00 minute mark, how many times he fills and flushes until it comes out clear.

No way a simple drain and fill is going to get the coolant anywhere it needs to be, in order to be considered clean. It took a total of 8 drains and flushes to achieve clean coolant. (Far right cup).

I have to go through a similar procedure on my older F-150 to get the same result. So this isn't something unique to Chrysler products, or newer vehicles. It's the nature of the beast.


This video feeds ones OCD. The implication is that the existing coolant is somehow so harmful that your engine is at risk of eminent failure.
 
What type of mileage were they looking at?
The 13 was about 100k miles, the 17 about 40k miles. Coolants were completely clear, no color changes or sediment of any kind that I could observe. Japanese (Honda) and German(Porsche)coolants
 
This video feeds ones OCD. The implication is that the existing coolant is somehow so harmful that your engine is at risk of eminent failure.
No, he's not "implying" any such thing. He's simply showing that it took 8 drain & fills to produce a clear flush. You can stop at whatever point your fancy is tickled.
 
Buy a coolant funnel with all the radiator/ pressure tank adapters. All the parts stores carry them. Yellow plastic funnel kit is around $40. Full the funnel until the system won't take any more coolant, then pinch various hoses burping more air out. Can raise front or rear of vehicle to air in air removal as well.

After hose pinching with hands shows no more bubbles in funnel, start engine. And turn heater on. Add more coolant to keep level in funnel to where you can see it. Feel heater hoses which should warm up within 2 min of engine running. If not, turn off engine and burp all hoses again.

Idle, rev engine until thermostat opens all while keeping coolant in the funnel as bubbles come out.

All my years as a mechanic this procedure has served me very well.

Only vehicles I've ever had to flush coolant y out of were GM Dexcool mud, and Ford products that had 10+ year old green IAT coolant that no one ever changed. We always used the steam cleaner and removed heater hoses to flush heater core and thermostat to flush block/ radiator. Hot water works best. Then compressed air to blow as much of the water out as possible before refilling with 50/50 of specified coolant and distilled.
 
Buy a coolant funnel with all the radiator/ pressure tank adapters. All the parts stores carry them. Yellow plastic funnel kit is around $40. Full the funnel until the system won't take any more coolant, then pinch various hoses burping more air out. Can raise front or rear of vehicle to air in air removal as well.

After hose pinching with hands shows no more bubbles in funnel, start engine. And turn heater on. Add more coolant to keep level in funnel to where you can see it. Feel heater hoses which should warm up within 2 min of engine running. If not, turn off engine and burp all hoses again.

Idle, rev engine until thermostat opens all while keeping coolant in the funnel as bubbles come out.

All my years as a mechanic this procedure has served me very well.
That method does not work in some vehicles and is rarely the most time-efficient. Vacuum filling is the only way to fill modern systems quickly and without overheating issues. Unfortunately this is one of those situations where there is a right/wrong answer.
 
That method does not work in some vehicles and is rarely the most time-efficient. Vacuum filling is the only way to fill modern systems quickly and without overheating issues. Unfortunately this is one of those situations where there is a right/wrong answer.
The OEMs all vacuum fill on the assembly line. This is true.

However, I'm not going to argue that using the above procedure is or is not going to work. It is just what I've done with well over 100 vehicle cooling systems after major/minor engine work. And has never let me down or had an air lock issue, which we all know is catastrophic.

It was part of my tool cleanup and put away time allowing the engine to warm up with the funnel attached at the rad. My 2020 RAM promaster 2500 with the 3.6 has a degass bottle which is in itself the funnel and serves the same purpose.

I'm not aware the 5.7 Hemi in a Jeep is any different. Other than a possibility of a bleeder somewhere in the system.

You can't go wrong with vacuum filling. But what shade tree mechanic has one of those?
 
As mentioned, your vehicle came from the factory with 10-year coolant. No need to worry about this til 2025.
 
The OEMs all vacuum fill on the assembly line. This is true.

However, I'm not going to argue that using the above procedure is or is not going to work. It is just what I've done with well over 100 vehicle cooling systems after major/minor engine work. And has never let me down or had an air lock issue, which we all know is catastrophic.

It was part of my tool cleanup and put away time allowing the engine to warm up with the funnel attached at the rad. My 2020 RAM promaster 2500 with the 3.6 has a degass bottle which is in itself the funnel and serves the same purpose.

I'm not aware the 5.7 Hemi in a Jeep is any different. Other than a possibility of a bleeder somewhere in the system.

You can't go wrong with vacuum filling. But what shade tree mechanic has one of those?
For around $100, most shade tree Mechanic’s can own one. I’m finding that the funnel doesn’t work on some vehicles without opening the bleeder valves or multiple heat cycles (vans with rear heat).

It’s just a lot easier and less stress to vacuum fill. For less money than paying for a single coolant service, anyone can own the tool and it will pay for itself overtime.
 
....... And has never let me down or had an air lock issue, which we all know is catastrophic.

How is having air, "catastrophic"?? I flushed my vehicles dozens of times over the years. You always get air into the system. It can't be avoided. After you refill, and run the engine up to temperature, then allow it to cool, the system self bleeds.

When the overflow reservoir remains constant, and you no longer have to add coolant after a few warm up / cool down cycles, you have effectively removed any trapped air that might have accumulated within the system. It's not a big deal.
 
How is having air, "catastrophic"?? I flushed my vehicles dozens of times over the years. You always get air into the system. It can't be avoided. After you refill, and run the engine up to temperature, then allow it to cool, the system self bleeds.

When the overflow reservoir remains constant, and you no longer have to add coolant after a few warm up / cool down cycles, you have effectively removed any trapped air that might have accumulated within the system. It's not a big deal.
Theoretically, if a pocket of air gets trapped in a coolant passage, it can cause that portion of the block/head to heat up significantly more than the surroundings. In extreme cases this can cause cracked blocks or failed head gaskets. Sort of an issue on some VQ products.

Also, trapped air does not always come out after a few heat cycles. Some cooling systems are just not friendly to self-purging.
 
I flushed my cutlass ciera by doing daily drain and fills with water for a week along with my normal driving around. After the week it was coming out looking pretty good. Then I dumped 100% AF in.

Way less fiddling than splicing into heater lines, removing thermostats, whatever. I like the idea of heat-cycling each water load to help it find all the nooks and crannies in the water system.

My tap water's great but I understand if AZ water has minerals you wouldn't like. The cheap guy in me thinks the first couple flushes might be ok with tap water before switching to distilled though.
 
I flushed my cutlass ciera by doing daily drain and fills with water for a week along with my normal driving around. After the week it was coming out looking pretty good. Then I dumped 100% AF in.

Way less fiddling than splicing into heater lines, removing thermostats, whatever. I like the idea of heat-cycling each water load to help it find all the nooks and crannies in the water system.

My tap water's great but I understand if AZ water has minerals you wouldn't like. The cheap guy in me thinks the first couple flushes might be ok with tap water before switching to distilled though.

I'm thinking of doing something along these lines as well. I'm going to just suck out the overflow reservoir, along with the radiator as far down as I can. Then refill it with 50/50 mix.

Then do the same in 500 or 1,000 miles. And just keep doing it. Eventually most all of it will get removed. I do the same with brake fluid and power steering fluid. As always, dilution is the solution to pollution.

It's certainly easier then doing repeated drains and fills. Especially when you have to start removing stuff just to get to the radiator drain.
 
Vacuum filling will take care of the air pockets:


2015 Jeep 5.7 should take MS-12106. Drain and refill with dealer coolant will suffice. Not sure what’s the obsession with flushing on this forum.
My guess is "the obsession with flushing" comes from a time when traditional coolants and older, under serviced cooling systems led to mucky looking radiators etc...and people (including myself) felt flushing was needed. With modern LL coolants and improved radiators etc...a D&R every 3 or so years should more than suffice, IMO...
PS: I also used to be a 3K oil change guy....I'm 'evolving' since joining BITOG.
 
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