Is generic green coolant okay, or will it cause damage to my TJ?

[Bowhunter]

From the research I’ve done, Jeep recommends HOAT coolant. But after a lot of reading on forums I was unable to get an answer if the generic green coolant is ok or if it will cause damage?

I ask because I need to add some coolant to my overflow reservoir. When I recently bought my Jeep, the coolant was bright green and looked to be new (radiator and hoses also look to be replaced), 4 weeks later the coolant is still bright green and looks new.

Is there any concern with the coolant type damaging the motor as long as I buy a coolant testing gauge to make sure I have freeze protection?

 

[billiebob]

coolant is coolant
you can buy expensive brand names or coolant on sale
it all does the same thing

 

[pagrey]

Polypropylene glycol which is sometimes green wont work or shouldn't be used. Ethylene glycol which is green most of the time is perfect. Zerex G-05 which is gold and HOAT is great to use especially because it can be mixed with ethylene glycol and nothing bad happens.

My opinion is that anything green in there is probably fine, it isn't going to damage anything or cause problems. If you start to have overheating issues then flush it.

 

[Steel City 06]

Be very careful what type you put in. Certain coolants, when mixed, will solidify into a gel. You can imagine how difficult it would be to clean out a bunch of congealed coolant from your heater core, radiator, and engine.

I would stick with the OEM stuff or Zerex G-05 or anything else that meets the Chrysler specifications.

In a pinch, the generic auto parts store coolant will be fine as long as it is listed as being HOAT compatible. It won’t have the same corrosion resistance as the factory specification stuff, but it probably won’t gel up.

Make sure you only dilute with distilled water (except for emergencies). The impurities in tap water can greatly accelerate corrosion.

 

[TJRick]

From the research I’ve done, Jeep recommends HOAT coolant. But after a lot of reading on forums I was unable to get an answer if the generic green coolant is ok or if it will cause damage?

I ask because I need to add some coolant to my overflow reservoir. When I recently bought my Jeep, the coolant was bright green and looked to be new (radiator and hoses also look to be replaced), 4 weeks later the coolant is still bright green and looks new.

Is there any concern with the coolant type damaging the motor as long as I buy a coolant testing gauge to make sure I have freeze protection?

View attachment 160827

As long as you stick to the same type, I think you will be fine.

Early model TJs (like mine) shipped from the factory with the green coolant in it. I don't think the cooling systems changed from 1997 - 2006.

I have been using the regular old Prestone yellow/green coolant in my Jeep since it was new. My Jeep is now 22 years old and has 150K miles on it. I flush it out and replace it about every 5 - 6 years and I haven't had any problems. I have always mixed it with *distilled* water, and I am still on my original thermostat and water pump!

 

[Bowhunter]

Be very careful what type you put in. Certain coolants, when mixed, will solidify into a gel. You can imagine how difficult it would be to clean out a bunch of congealed coolant from your heater core, radiator, and engine.

I would stick with the OEM stuff or Zerex G-05 or anything else that meets the Chrysler specifications.

In a pinch, the generic auto parts store coolant will be fine as long as it is listed as being HOAT compatible. It won’t have the same corrosion resistance as the factory specification stuff, but it probably won’t gel up.

Make sure you only dilute with distilled water (except for emergencies). The impurities in tap water can greatly accelerate corrosion.

If I added Ethylene glycol coolant to the reservoir, is there a chance I run into gel issue? Sounds like I need to flush out the system so I know what coolant I have.

I looked for the engine block drain plug and can’t seem to find that on my 4.0

 

[pagrey]

I don't think so, the gel issue is with pink stuff. I've never heard of a gel or precipitation issue mixing green.

 

[Zorba]

I'm a big believer in using the factory coolant, and the factory coolant ONLY. Especially on anything with aluminum in the system, which includes the TJ's thermostat housing if nothing else (water pump?). I've seen too much corrosion from running generic Prestone et al. It doesn't cost that much more for the factory stuff, and you don't change it that often. YMMV, and all that.

 

[Bowhunter]

I'm a big believer in using the factory coolant, and the factory coolant ONLY. Especially on anything with aluminum in the system, which includes the TJ's thermostat housing if nothing else (water pump?). I've seen too much corrosion from running generic Prestone et al. It doesn't cost that much more for the factory stuff, and you don't change it that often. YMMV, and all that.

I agree with the how little extra it costs, but I’d need to do a full drain/flush because mixing orange and green is no good. I was able to find the block drain plug so I should be able to flush everything

 

[cliffish]

If it is a new to you TJ, flush and change all the fluids, coolant, both Diffs, oil and trans/transfer case fluids.

 

[MountaineerTom]

I looked for the engine block drain plug and can’t seem to find that on my 4.0

On my ‘06 4.0, it’s on the drivers side below the intake and exhaust manifold. It’s a square drive plug. I don’t recall off the top of my head, 8mm maybe. Buts it’s not a 3/8” drive.

 

[PatMc]

coolant is coolant
you can buy expensive brand names or coolant on sale
it all does the same thing

No, it's not. The adults are talking...please sit down.

To the OP...different chemistries exist for different materials, different service intervals, different anti-cavitation properties based on waterpump and coolant passage designs...etc... which is why there are almost as many types of coolant as there are engine oils. All serve a purpose.

That being said, the Jeep 4.0 is a cast iron chunk not unlike the first overhead valve straight six that AMC made back when there was only one type of coolant, so I wouldn't hesitate to use it....keeping in mind that it needs to changed every couple years or 24K miles...whatever comes first. The modern coolant that is spec'd for the engine will be good for 100K miles or 8+ years without having to fuss with it...

Yes, the "correct" coolant costs another $40, but in comparison to the basic universal garbage...you don't have to spend 3 hours changing it 3 times over the next 8 years, you don't have to spend $100 on universal garbage coolant 3 extra times over the next 8 years, and you don't have to dispose of coolant an extra 3 times over the next 8 years.

Sometimes you save money buying the most expensive product.

 

[Bowhunter]

No, it's not. The adults are talking...please sit down.

To the OP...different chemistries exist for different materials, different service intervals, different anti-cavitation properties based on waterpump and coolant passage designs...etc... which is why there are almost as many types of coolant as there are engine oils. All serve a purpose.

That being said, the Jeep 4.0 is a cast iron chunk not unlike the first overhead valve straight six that AMC made back when there was only one type of coolant, so I wouldn't hesitate to use it....keeping in mind that it needs to changed every couple years or 24K miles...whatever comes first. The modern coolant that is spec'd for the engine will be good for 100K miles or 8+ years without having to fuss with it...

Yes, the "correct" coolant costs another $40, but in comparison to the basic universal garbage...you don't have to spend 3 hours changing it 3 times over the next 8 years, you don't have to spend $100 on universal garbage coolant 3 extra times over the next 8 years, and you don't have to dispose of coolant an extra 3 times over the next 8 years.

Sometimes you save money buying the most expensive product.

I agree with buying the better product up front but judging by how clean the coolant looks, it was recently replaced. One thing I’m getting hung up on is the potential of mixing the green with HOAT and creating a if I don’t flush all of the green out of my block, heater core and radiator.

This Preston all vehicle says to be compatible with all types of coolant. Because I just need to fill reservoir, considering going this route..

Doesn’t prevent the inevitable that I would need to flush the system within the next few years assuming the coolant in my Jeep is the generic green stuff

 

[WHBNM]

I would flush and fill with Zerex G05 when you need some "garage time."

 

[PatMc]

I agree with buying the better product up front but judging by how clean the coolant looks, it was recently replaced. One thing I’m getting hung up on is the potential of mixing the green with HOAT and creating a if I don’t flush all of the green out of my block, heater core and radiator.

This Preston all vehicle says to be compatible with all types of coolant. Because I just need to fill reservoir, considering going this route..

Doesn’t prevent the inevitable that I would need to flush the system within the next few years assuming the coolant in my Jeep is the generic green stuff

View attachment 160991

I will ask you this...given the following... (quoted from the document you posted)

IAT stands for "inorganic acid technology", OAT stands for "Organic Acid Technology"....

It can be one or the other, not both. There isn't a single product that can meet both specs. How can this miracle coolant exist?.... (hint...it can't)

The OE coolant chemistry meets the spec called out.

This is considerably more critical with modern engines...not the cast iron junk that powers our jeeps, but it's still important to understand that the prestone coolant does little more than blend in with whatever you add it too such that the color matches, but can't possibly match the chemistry. It's marketing wank....that's all.

 

[MountaineerTom]

@Bowhunter , here's a couple pics I took in November when was working on my cooling system.

One of these two is what I used to get the plug out with. Square Head Drain Plug Sockets

 

[Bowhunter]

I will ask you this...given the following...

IAT stands for "inorganic acid technology", OAT stands for "Organic Acid Technology"....

It can be one or the other, not both. There isn't a single product that can meet both specs.

The OE coolant chemistry meets the spec called out.

This is considerably more critical with modern engines...not the cast iron junk that powers our jeeps, but it's still important to understand that the prestone coolant does little more than blend in with whatever you add it too, but can't possibly match the chemistry. It's marketing wank....that's all.

Thanks for the info.

Guess the only way I can put this to bed is to drain/flush the coolant system and add the HOAT coolant

flushing the radiator is no issue but the block and heater core seems to be more difficult.is this the correct process:

Heater Core
-Unhook one end of both heater core hoses(unhook one end of the in and out hoses), pore distilled water in one of the hoses until clear, then pore water in the opposite heater core hose until clear

Block
-With the bottom radiator hose unhooked, pour distilled water into the heater core hose that leads into the engine block? This is the step I’m not sure about
- Remove the coolant block drain plug, reinstall with thread sealant (loktite?)

 

[Bowhunter]

@Bowhunter , here's a couple pics I took in November when was working on my cooling system.

One of these two is what I used to get the plug out with. Square Head Drain Plug Sockets

View attachment 161000

View attachment 161001

Thank you! I located the drain plug.

Could you please explain how to flush the block out with the distilled gallon method? Do you flush and then remove the block drain plug? Or remove first and then flush and then reinstall?

 

[MountaineerTom]

I used some Prestone super flush before changing all my components. I drained the block and radiator, put the plugs back in, refilled with distilled water and the super flush. Drove around normally for a couple days. Drained radiator and block again, refilled with distilled water again, ran the engine up to operating temp. I repeated this a couple more times until nothing but clear distilled water drained out of the block. Them mixed up 50/50 distilled water and Zerex G-05.

Then I replaced all hoses, water pump, thermostat and housing and the radiator.

If you're not replacing components and just want to get all the old coolant out, Id just do the radiator/block drain/refill with distilled two or three times until clear water drains out, then refill with 50/50 mix of Zerex G-05.

I used this stuff on the block drain plug (and coolant temp sensor and water pump pipe) during the final assembly. Works well and doesn't harden. Haven't had any leaks. I kept it off the first couple threads of the plug, sensor and pipe so it didn't get into the coolant.

 

[Mr. Bills]

From the research I’ve done, Jeep recommends HOAT coolant. But after a lot of reading on forums I was unable to get an answer if the generic green coolant is ok or if it will cause damage?

Is there any concern with the coolant type damaging the motor as long as I buy a coolant testing gauge to make sure I have freeze protection?

The HOAT coolant recommended by Jeep is an ethylene glycol coolant.

Conventional green coolant is also an ethylene glycol coolant.

HOAT type coolant helps reduce deposits and corrosion over the long term and is typically marketed as a long life coolant, frequently with a 5 year flush interval.

The two coolants are compatible, but any long life properties of the HOAT coolant are reduced to the service life of conventional green coolant, which is approximately three years under typical driving conditions.

I wouldn't worry too much about running "conventional green" for awhile. It isn't necessary to throw it out simply because it isn't HOAT. The next time you flush your coolant as part of your regular maintenance schedule you can buy a HOAT coolant like Zerex GO5.

In the meantime you can top it off with conventional bright green coolant. If you have any concerns that the green stuff in your radiator now isn't ethylene glycol, then just top off with distilled water rather than use any coolant at all. There's nothing magic about a 50/50 ratio. In areas that get super cold that ratio may be necessary in the dead of winter but in warmer climates a 60/40 ratio is just fine. In some sports car circles, owners from Arizona and other very hot places advocate a 65/35 ratio of water to coolant during summer because the antifreeze properties are not necessary, there is still enough lubricity for the water pump and other cooling system parts in a 65/35 mix, and plain water actually cools better than coolant.