Automatic Transmission fluid change interval s on 2021 JT

[HankB]

Pretty much this.

There is such a thing as over maintaining something to the detriment of the item you are maintaining. Fleet managers of large vehicle fleets call it something like "Theory of Replacement" which basically states if you over maintain something, you incur needless costs upfront. If you fail to maintain it not enough, you incur larger costs sooner than expected. It is a balancing act.

Very true, there is such a thing as over maintaining. It all comes down to long term cost benefit analysis. But that said, that concept is applied to fleets with hundreds of vehicles running up hundreds of thousands of miles and thousands of hours of operation. Having used this in practice with very large fleets, my take is that it’s a concept that does not scale downwards all that effectively.

Keep in mind changing the fluid in modern transmissions is not just pulling the plug and letting a dozen quarts drip into the catch pan. Many transmissions require actual mechanical work: to make measurements and adjustments, and clean out the nooks and crannies, etc. These all form opportunities for gaskets to be installed wrong, or badly, fasteners to not be torqued, or improperly repaired, and so on. It’s easy to create a situation where the cost of the cure is greater than the disease.

As for the discussion at hand, Papa is 10,000% right; Heat is the killer. You have a temperature gauge for your transmission, pay attention to it. Especially when you are putting stress on the vehicle, e.g. towing, or off road. This also highlights part of the problem with this kind of discussion; the jt is a product where there is a very wide spectrum of what constitutes “acceptable use”. And we have a question of when to replace something that is influenced by the level of use. The short version, everybody is different and the replacement need will be different. Will I need to replace the trans fluid on my JT that is used exclusively on roadways, occasionally in snow, Where the heaviest load will be 1000 lbs of pellets, three times a year? Hell no, even if I keep it for ten years. Is that going to be the same for someone who regularly tows a 5000 LB boat? Also He’ll no, that guy is probably going to be a good candidate, especially if it’s someplace hot during boating season.

Oil sample analysis has been brought up. This is a great tool as a single point of time analysis. It is even better as a long term tool where the first and subsequent tests are used to form a baseline, so start early with the testing and keep a file of the results.

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[Maximus Gladius]

I’ve read this whole thread, following your saga. Did I miss where your transmission was replaced? By FCA? Or did you buy one from the GM Dealer? Any update to the legal action?
Thanks

Hey Duran, I did not accept the deal from the local GM dealer as I was in thick with AMSOIL, FCA and I had a lawyer write up a legal demand letter to both the first dealership that handled my ”glycol contamination/transmission whine/oil analysis” poorly and the other letter went to FCA.

Amsoil did nothing but give me their “warranty secure” paperwork. Their legal dept never got involved except at the very end with a couple emails back and forth with me and then they dropped off the face of the earth.

Legal demand letter ($1500cad) gave the dealership and FCA 3 or 4 months to repair. Letter was ignored. Lawyer said it’ll take 2 years before I see the inside of a court room.

I decided I wasn’t going to pay for this truck for the next two years and can’t use it. I wrote an email to the President/CEO/Chairman of Stellantis and his executive staff, needing help. I cc’d the everyone involved and about 3 days later FCA phoned me and said they were looking into it. The investigation lasted 3 weeks. At the end, FCA engineers contacted ZF and was told by them “AMSOIL is not an approved equivalent oil, warranty denied.” FCA said transmission was working until I flushed it and put in AMSOIL”. Amsoil said “it was the glycol contamination that destroyed the transmission, it wasn’t their oil.”
I told AMSOIL lawyer, your oil may not have destroyed my transmission but the use of it destroyed my warranty.” I never heard from them again.

I then contacted the service manager at a second dealership before I spoke further into my situation, he already knew about it and told me the DSM(district service manager) doesn’t want anyone to get involved. But, he listened to me and he wanted to check some things out, so the truck went in.

He suspected the “heater unit”’on the side of the transmission MAY have been the defective part to contaminate the transmission with coolant so they took it off and tested it for leaks. It was sound, nothing wrong. He said “the only way coolant got in there was to have been put in there.”

He put it in writing and I went to my insurance company and filed a vandalism claim. It was approved. In fact they also approved the replacement of the coolant consuming engine FCA would not replace. Thanks NORM, FCA engineer that had no problem to my consuming 10-12 ounces coolant per oil change.

So with my insurance approving the repairs, they dropped $24k cad and I got a new engine and 2nd transmission.

 

[Stinggrey 21 Rubi]

I installed an APE trans pan today. What a PITA, anyway I was surprised how much feric material had gathered on the magnets in the stock pan after only 20 thousand miles. I am glad I replaced the fluid although the fluid itself did not look bad.

 

[Gren71]

I still haven’t gotten to do mine…93,000 miles….ugh

 

[Maximus Gladius]

I still haven’t gotten to do mine…93,000 miles….ugh

Good for life man! The transmission is good for the life of the oil and the oil is good for the life of the transmission! I’d say there’s nothing to worry about!

For all the trailering you’ve done and it’s still going strong, ….impressive

 

[Gren71]

Good for life man! The transmission is good for the life of the oil and the oil is good for the life of the transmission! I’d say there’s nothing to worry about!

For all the trailering you’ve done and it’s still going strong, ….impressive

Lol ty

My oil analysis came back good when i sent it around 85,000ish. But definitely something i need to stop stalling on and just get to it. I’ve recently felt like im seeing 8th less and im wonder (coming from a place of total ignorance on thr subject) if the trans is wearing down or wearing out. Specifically 8th since i do a lot of highway in 8th.

 

[ShadowsPapa]

Lol ty

My oil analysis came back good when i sent it around 85,000ish. But definitely something i need to stop stalling on and just get to it. I’ve recently felt like im seeing 8th less and im wonder (coming from a place of total ignorance on thr subject) if the trans is wearing down or wearing out. Specifically 8th since i do a lot of highway in 8th.

And most of the time you'd be fine. I've seen transmissions go way way longer with no service. But - don't recommend it.
Most could likely take one of these that far without trouble and if the analysis comes back clean, you are likely fine. But - the chemistry does tend to break down with heat and pressure.
My take - your transmission is likely fine, but I'd change it.

 

[kevman65]

The problem with transmission service on the JT or JL, it's not a simple cut and dried procedure.
There are multiple steps needed, transmission temperature has to be in a certain range for each step, and there's no guarantee all contaminants and old ATF gets removed from system.
With all of that thrown together, it's an expensive process if done correctly.

 

[ShadowsPapa]

and there's no guarantee all contaminants and old ATF gets removed from system.

That's been true since the 1950s. Even those with converter drains don't let all the fluid out. Accumulators, servos, clutch packs, valve body, a lot of fluid remains.
But it doesn't really matter as even replacing only 2/3 of the fluid at a time is a big help.
Most contamination will settle. If the fluid is warn, you are stirring things up and flushing most out anyway.
Since these are "sealed" there's not much in the line of contamination to remain in these.

 

[RidinDirty]

Reviving thread. So are we assuming the lifetime of this transmission to be 150K? I understand it will need a rebuild at that time in any case? It'll probably the same time I do a 392 swap. LOL.

 

[Gren71]

Reviving thread. So are we assuming the lifetime of this transmission to be 150K? I understand it will need a rebuild at that time in any case? It'll probably the same time I do a 392 swap. LOL.

Well F my life I hope this thing doesn’t beed a rebuild at 150k

 

[Hootbro]

Reviving thread. So are we assuming the lifetime of this transmission to be 150K? I understand it will need a rebuild at that time in any case? It'll probably the same time I do a 392 swap. LOL.

I think the 150K number is just a stick a pin in it value number if never serviced. But there is plenty examples in the BMW world of ZF 8 Speed transmission going over 200K with no service and to 300K+ with regular service interval.

 

[ShadowsPapa]

Reviving thread. So are we assuming the lifetime of this transmission to be 150K? I understand it will need a rebuild at that time in any case?

I know of TF727s and 998s that go well over that without trouble if serviced and cared for at even intervals of 70K miles and that's old-school transmissions and fluid of the 70s-90s.

I think the 150K number is just a stick a pin in it value number if never serviced. But there is plenty examples in the BMW world of ZF 8 Speed transmission going over 200K with no service and to 300K+ with regular service interval.

It's all about how they are used and driven to a large extent. Heat kills, over-loading kills, and it used to be stated in owner manuals and other documents "if you get stuck don't rock the car using the transmission".
One transmission I rebuilt for a traveler years ago was a C4 in a Mustang. She was towing a U-Haul trailer and the trailer was packed, the car was also packed, with all of her worldly goods. She was moving across the country west to a teaching job in Colorado.
She fried the transmission. I did the rebuild and the boss and I both told her she was going to fry that little C4 again towing all that load and worse, from here it's all up hill (quite literally, watch your elevation change from here to there)
She got into CO and fried it again.

There's no real rule or way to say how a given transmission will last because it's based so much on how it's used and driven. But these, with service at say 60-80K miles, the superior engineering and machining, the modern fluids and so on - should easily last well over 150,000 miles. Why not? Automatics of the past could.

 

[MattKay]

What is a good (green) range for transmission temps and what is the yellow and red range for temps?

I check my temps all the time. They change a lot when I’m towing something tho. Still not clear what temps swings are fine and what are problematic.

 

[RidinDirty]

In any case, I'm having a dealer transmission fluid service with my next oil change as I just passed 60K (no issues). I'm in AZ and the heat here/environment is extreme so a little preventative maintenance is better than $3500 or more for a new ZF.

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