Automatic Transmission fluid change interval s on 2021 JT

[ShadowsPapa]

I've not looked into how these transmissions are cooled - in-radiator cooling or a distinct, independent cooler like the early Grand Cherokees had down low in the radiator area........ but a service person should know that.
Anyway, the only way to get "antifreeze" or "Coolant" (glycol............) in is if these do have an in-radiator cooling for the transmission AND if that tube inside the radiator is damaged.
I'm going by OLDER systems, so could be wrong, but in the old days - it literally was not possible unless the tube that was in the radiator rotted and allowed coolant in. But since the ATF was under some pressure itself before the cooling system got hot, you'd have ATF in the radiator first.
The older systems (again, these may be different) literally had a coil in the radiator that the ATF was pumped through - and when things like the fittings got loose or bad or the joints gave out, you lost coolant but not ATF.
So I guess that's a long way of saying "how the hell could you get coolant into a transmission?"
OR - do we have a base test on fresh ATF from MOPAR to see if there's naturally glycol in the ATF?

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[ThatStinging_Jeep]

Most manufacturers say lifetime fill so that they can lower the cost of ownership, and use that against their competitors. There are other reasons as well, but as was stated above stick to ZF's recommendation, or change it more often if you tow regularly.
Personally, I like to change fluids before what's recommended and usually on intervals I can easily remember. Oil every 5k, diffs, manual trans and transfer cases every 30k and auto trans every 50k. Fluid is cheap compared to a new gearbox.

And to that i say Amen,i love keeping my engine happy so i religiously changed it at 4k ish miles,yeah it was most likely a waste of money but wayy better than replacing a new motor and so on with other components as well
still dont know if i should do that on my new ecodiesel since.....it is a diesel but good lord is the oil pretty black/dark at only 3k miles
on the first oil change im most like likely gonna go with the insane diesel oil filter bypass kit,i was gonna just drop money on a set of wheels but my motor is damn more important that some nice wheels........but man are they tempting

 

[ShadowsPapa]

And to that i say Amen,i love keeping my engine happy so i religiously changed it at 4k ish miles,yeah it was most likely a waste of money but wayy better than replacing a new motor and so on with other components as well
still dont know if i should do that on my new ecodiesel since.....it is a diesel but good lord is the oil pretty black/dark at only 3k miles
on the first oil change im most like likely gonna go with the insane diesel oil filter bypass kit,i was gonna just drop money on a set of wheels but my motor is damn more important that some nice wheels........but man are they tempting

In my experience with diesels in decades passed, it doesn't take many miles for the oil to be BLACK. (I've owned several diesel tractors and as a mechanic did my share of oil changes on diesel cars and trucks years ago - it was always easy to tell which oil came from a diesel)
IMO the oil change intervals in the book are for best case scenarios. Only you know the conditions such as temperatures, loads, speeds driven, etc. If you choose to change it at 4K - it's your truck, you can't hurt a thing by more frequent changes. Maybe your engine will be like one I worked on years ago where the guy changed oil really frequently and did other routine maintenance religiously, and when it finally needed valve seals and things pulled apart more due to age than wear, the inside of that engine looked almost new, and there was no ridge at the top of the bores.
100,000 miles and all it needed was a gasket set - no "hard" or machine work was done on it.
Don't sweat the black, though - that's diesel, in my experience. Other colors - I might worry. Heck, send a sample in to be tested. Will not only make you feel good and prove you right - but it might be useful for a future sale as you can show how good the oil still was when you changed it.

 

[MrZappo]

There used to be a good video on YouTube showing how to do the fluid swap on one of these 8 speed transmissions. The guy appears to be an instructor at a vocational school. He's in an electric wheelchair, but he knows his stuff. He's working on a Chrysler sedan, but the process of changing the trans. fluid is the same as the Jeep. See if you can find that video. I lost the link. It'll give you an idea of how to tackle this job.

Thank god. I figured that being in a wheelchair would also mean that he knew nothing about transmissions ...

Whew ... What a relief ...

 

[ShadowsPapa]

Thank god. I figured that being in a wheelchair would also mean that he knew nothing about transmissions ...

Whew ... What a relief ...

Good catch........... Person first, disability last.
I worked IT at VocRehab for a dozen years - and being married to a woman with a life-long "disability" you become blind to such things.

Funny thing - adults stare, most kids ignore it.

 

[ThatStinging_Jeep]

In my experience with diesels in decades passed, it doesn't take many miles for the oil to be BLACK. (I've owned several diesel tractors and as a mechanic did my share of oil changes on diesel cars and trucks years ago - it was always easy to tell which oil came from a diesel)
IMO the oil change intervals in the book are for best case scenarios. Only you know the conditions such as temperatures, loads, speeds driven, etc. If you choose to change it at 4K - it's your truck, you can't hurt a thing by more frequent changes. Maybe your engine will be like one I worked on years ago where the guy changed oil really frequently and did other routine maintenance religiously, and when it finally needed valve seals and things pulled apart more due to age than wear, the inside of that engine looked almost new, and there was no ridge at the top of the bores.
100,000 miles and all it needed was a gasket set - no "hard" or machine work was done on it.
Don't sweat the black, though - that's diesel, in my experience. Other colors - I might worry. Heck, send a sample in to be tested. Will not only make you feel good and prove you right - but it might be useful for a future sale as you can show how good the oil still was when you changed it.

Hey thanks for the info man,yeah I Know I'm just used to seeing brown oil coming out of my gasser engines all the time,doesn't help that the egr is in place in these diesels but oh well...dark oil it is

 

[Hootbro]

Just replaced my transmission fluid two week ago at 30K miles.

Pretty easy. Let it sit overnight and got about 2 quarts out just removing the fill/level plug. Mity-Vac about 4 more quarts out of the pan. Dropped the pan, replaced the filter and reinstalled torque to spec.

Pumped in about 4 quarts of fluid, installed fill/level plug. Started engine and ran it through the gears a couple of times keep it above 2K RPM and the nano second trans temp reached the minimum check temp at 88F, removed check/fill plug and pumped fluid until it spilled out which happen to roughly be 2 quarts and called it good.

A few notes:

1. Pan gasket is reusable. Just inspect and do not ham fist it on and off. Pan and gasket will drop and should not need any pry tool

2. Unlike some Youtube video instructions, you do not need a high end scan tool for trans temp monitoring. The dash gauge for trans temp is good enough. Unless corrected, best I can tell is that there is no dedicated trans temp sensor and what the vehicle reports for trans temp is actually deciphered from coolant and oil temp readings.

3. Filter is bolted to the pan and both can be dropped down onto the exhaust crossover pipe and moved forward to get out and back end. No need to drop exhaust cross over pipe.

Took no pics but for 30K miles, the crude in the pan bottom was not really that bad with just slight wear material film on the two inside pan magnets.

3.5K miles since the change and no issues. I know ZF recommends a 50K-80K mile change on most of their transmissions and think that is a good habit to follow regardless of what any "Fill For Life" direction the owners manual may say.

 

[ShadowsPapa]

I know ZF recommends a 50K-80K mile change on most of their transmissions and think that is a good habit to follow

Yuuuuup. The maker of the transmission know more about it than any other entity.
For most ordinary folks driving it as a simple vehicle, occasional truck duty, life may be fine (assuming say 100,000 miles??) but towing and bad weather change things.
I can see doing 60K on mine based on driving habits, usage, towing is minimal, etc.
It's still a machine with moving and wearing parts, friction surfaces and precision shuttle valves inside.

 

[Nitroexpress]

Reviving this thread as I don't understand a few items regarding ZF transmission service. I don't want a flush, and I don't want a dealer involved. So my questions are:

1) I have read two options for filter replacement. One says the filter is bolted to the pan, so you just replace the filter, the other states that you MUST buy a kit that contains the integrated pan/filter. It shows both ways to purchase on the MOPAR parts site: https://store.mopar.com/transmission-filters
- Pan and filter part number 68362041AB
- Filter part number 68417054AB

2)It also appears to me that some pans may be plastic and some metal? Mine is metal. Is this a case that if you have a plastic pan you replace the whole assembly(pan and filter) and a metal pan you only replace the filter?

3) Why is servicing this type transmission portrayed as some kind of 'black art'? I see descriptions for the service being labeled "complicated" and "a Pain compared to the old days". As far as I can tell, a "sealed" transmission means there is no dipstick and you fill and check fluid level through a plug, which is no big deal?? The only thing I can see that may be "complicated" is that you must get the fluid level correct at a specific temperature range of 88-122 degrees, which seems as simple as shifting through the gears while watching the built in transmission temperature gauge. With a drain plug on the pan, this service seems less messy than 'the old days'.

Thanks for any insight, I plan to do this service soon.

 

[Maximus Gladius]

Reviving this thread as I don't understand a few items regarding ZF transmission service. I don't want a flush, and I don't want a dealer involved. So my questions are:

1) I have read two options for filter replacement. One says the filter is bolted to the pan, so you just replace the filter, the other states that you MUST buy a kit that contains the integrated pan/filter. It shows both ways to purchase on the MOPAR parts site: https://store.mopar.com/transmission-filters
- Pan and filter part number 68362041AB
- Filter part number 68417054AB

2)It also appears to me that some pans may be plastic and some metal? Mine is metal. Is this a case that if you have a plastic pan you replace the whole assembly(pan and filter) and a metal pan you only replace the filter?

3) Why is servicing this type transmission portrayed as some kind of 'black art'? I see descriptions for the service being labeled "complicated" and "a Pain compared to the old days". As far as I can tell, a "sealed" transmission means there is no dipstick and you fill and check fluid level through a plug, which is no big deal?? The only thing I can see that may be "complicated" is that you must get the fluid level correct at a specific temperature range of 88-122 degrees, which seems as simple as shifting through the gears while watching the built in transmission temperature gauge. With a drain plug on the pan, this service seems less messy than 'the old days'.

Thanks for any insight, I plan to do this service soon.

It’s the gasket and fasteners that are a one time use. Yes, the filter is fastened on the pan with nuts but unless you can get a gasket by itself, there’s no use in buying it all split up.

The oil change is super easy but you must reflash or relearn the transmission when the oil is changed and would take some gizzmo to do that.

What is your MILAGE? Would very much appreciate it if you would send off a sample of your oil to a lab so I can at least compare what “good” metal numbers look like to that of mine that imploded at 32k kms due to glycol contamination.

EDIT UPDATE: Jan 2023
1. The info I gave above about needing to replace pan and gasket and fasteners is based on being told this from the dealership parts department back in early 2021. We all find out today (Jan 2023), this is not the case - gasket/pan and fasteners are reusable. Still need to pick up a filter that is held down with a couple nuts to the pan.

2. Another member here has written ZF with regard to having to “reflash” transmission after fluid change and (paraphrasing here) ‘is not recommended as this has caused more problems before’. (I read the email)

I had asked the outfit that I turned to to “flush” my transmission, (because it had glycol contamination in it and dealership didn’t want to do anything about it except take all my money for multiple pan drops) if a reflash was necessary? He said ‘it’s up to the discretion of the tech and the reflash would require it to be towed over to a dealership to have done. It’s done if certain issues were found like slipping and clunks and stuff. It’s not done on a normal operating transmission’.

 

[ShadowsPapa]

3) Why is servicing this type transmission portrayed as some kind of 'black art'? I see descriptions for the service being labeled "complicated" and "a Pain compared to the old days". As far as I can tell, a "sealed" transmission means there is no dipstick and you fill and check fluid level through a plug, which is no big deal?? The only thing I can see that may be "complicated" is that you must get the fluid level correct at a specific temperature range of 88-122 degrees, which seems as simple as shifting through the gears while watching the built in transmission temperature gauge. With a drain plug on the pan, this service seems less messy than 'the old days'.

Because it IS complex. They don't really want driveway "mechanics" messing with it. The tolerances in these are crazy tight.
Have you see how you add fluid? There's no dipstick. You do it from under the vehicle
No big deal? Go watch the youtube videos of a guy doing the fluid check - it can take hours as if you miss that temperature mark, you do it again. It's a small window.
Yeah, you can do it, but you've not worked under a vehicle, watching for the correct temperature and working quickly to take a check under a truck with hot exhaust.
No, it's not as simple as switching through the gears and watching. In fact, with some of the ZF transmissions, there's things you don't want to do while doing the check and flipping through gears to get it warmed up is likely among them.
There's no dipstick for a reason, and special instructions for a reason. You see the words "pain" and "complicated" because it is.
A member has been through it.

(now he also has a trashed transmission but that may or may not be related)

Guess what - I'm a former auto tech, I used to rebuild transmissions as part of my job - I'm not messing with my JT transmission.

 

[Maximus Gladius]

Because it IS complex. They don't really want driveway "mechanics" messing with it. The tolerances in these are crazy tight.
Have you see how you add fluid? There's no dipstick. You do it from under the vehicle
No big deal? Go watch the youtube videos of a guy doing the fluid check - it can take hours as if you miss that temperature mark, you do it again. It's a small window.
Yeah, you can do it, but you've not worked under a vehicle, watching for the correct temperature and working quickly to take a check under a truck with hot exhaust.
No, it's not as simple as switching through the gears and watching. In fact, with some of the ZF transmissions, there's things you don't want to do while doing the check and flipping through gears to get it warmed up is likely among them.
There's no dipstick for a reason, and special instructions for a reason. You see the words "pain" and "complicated" because it is.
A member has been through it.

(now he also has a trashed transmission but that may or may not be related)

Guess what - I'm a former auto tech, I used to rebuild transmissions as part of my job - I'm not messing with my JT transmission.

Papa, you’re scaring the poor guy. It’s not hard and no, my checking my oil and pulling a sample and having a certified transmission shop do the flush did not implode my transmission. Come on now, you know my story intimately and focus needs to target the glycol contamination which will destroy every transmission it contaminates.

 

[Nitroexpress]

In my experience with diesels in decades passed, it doesn't take many miles for the oil to be BLACK. (I've owned several diesel tractors and as a mechanic did my share of oil changes on diesel cars and trucks years ago - it was always easy to tell which oil came from a diesel)
IMO the oil change intervals in the book are for best case scenarios. Only you know the conditions such as temperatures, loads, speeds driven, etc. If you choose to change it at 4K - it's your truck, you can't hurt a thing by more frequent changes. Maybe your engine will be like one I worked on years ago where the guy changed oil really frequently and did other routine maintenance religiously, and when it finally needed valve seals and things pulled apart more due to age than wear, the inside of that engine looked almost new, and there was no ridge at the top of the bores.
100,000 miles and all it needed was a gasket set - no "hard" or machine work was done on it.
Don't sweat the black, though - that's diesel, in my experience. Other colors - I might worry. Heck, send a sample in to be tested. Will not only make you feel good and prove you right - but it might be useful for a future sale as you can show how good the oil still was when you changed it.

Agree that diesel oil turning black is an indicator of nothing and it happens quick.
I would offer a counter point to:
"Only you know the conditions such as temperatures, loads, speeds driven, etc." - That's exactly what the oil life monitor does. The only way to get more accurate intervals is to combine the oil life monitor with a used oil analysis.

 

[ShadowsPapa]

"Only you know the conditions such as temperatures, loads, speeds driven, etc." - That's exactly what the oil life monitor does. The only way to get more accurate intervals is to combine the oil life monitor with a used oil analysis.

Yes.

And you could compare the analysis to what the monitor said and get some idea of how close it is.

 

[Maximus Gladius]

It can seem daunting to check the fluid level if it’s over thunk. Your “temperature window” can be an hour to go through with the vehicle level and at idle. Once it reaches temp, it takes 3 minutes to check the level. Your not worrying about gear and clutch tolerances because you’re not touching them. It’s oil level your checking or if doing a pan drop, it’s putting the oil back in and having a pressurized system to feed it until the oil dribbles back out the fill hole. It’s a transmission that runs on oil. Nothing has changed in decades. The scary part is letting yourself be scared

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