42RLE fluid replacement after 100,000 miles: what are the risks?

[Jorge Bolivar]

My coworker and I have been discussing the risk of replace (not flush) the 42rle fluid on his LJ that has more than 100, 000 miles on it and chances are that the same never has serviced. I know the subject is quite conflictive due the different experiences, myths, mentality and/or knowledge, but like to hear what yo'all input it is.

 

[Stockli]

I think new fluid is fine. I have heard flushing can loosen up debris and clog up passages but I have not experienced this. I think that is more the case in trans that have been abused and are acting up and as a last ditch fix they flush the trans.

No surprise it dies shortly after, it was already on the way out.

My opinion, new fluid won’t hurt anything but I’m not sure I would risk a flush.

 

[Rob5589]

The rec on my Honda is trans fluid every 100K and my Silverado is 80K if I recall correctly. I have been hearing the old "never change auto trans fluid..." deal since before I could drive but have never personally experienced an issue nor know anyone that has.

 

[Jerry Bransford]

There are ZERO risks in changing the ATF after 100k miles, or at any mileage for that matter. ZERO! It's always a good idea, providing you use the proper ATF+4 as all of our Jeep automatic transmissions require.

The old wive's tales of transmissions being damaged from having their ATF changed after a lot of miles are just that, old wive's tales. If a transmission fails soon after having its ATF changed after too many miles of not having been changed, it was about to fail from old/bad/dirty/burnt ATF anyway.

 

[Chris]

No risks at all IMHO. Whoever started the myth that changing your transmission fluid after X amount of years or miles is out of their mind. As long as you use the proper transmission fluid, you're doing no harm to your transmission at all, only good.

This is another one of those internet myths that has so basis in reality if you ask me.

 

[tquig01]

There are ZERO risks in changing the ATF after 100k miles, or at any mileage for that matter. ZERO! It's always a good idea, providing you use the proper ATF+4 as all of our Jeep automatic transmissions require.

The old wive's tales of transmissions being damaged from having their ATF changed after a lot of miles are just that, old wive's tales. If a transmission fails soon after having its ATF changed after too many miles of not having been changed, it was about to fail from old/bad/dirty/burnt ATF anyway.

100% agree. Just looking at how an auto tranny works should make this very clear, even without being able to repair one. Auto transmissions typically die because of a failure of one of three main components

- torque converter: internal lock-up clutch glazes and slips or wears down to the point of slipping- both caused by heat due to bad fluid
- internal bands / discs: same as torque converter clutch above
- value body: debris restricts internal vales / sticky ball bearings restricts fluid flow, leading to excess heat, which causes the two failures above

Performing regular fluid changes and filter changes prevents this. Nothing will un-glaze the clutch surfaces - once damage is done, its done. Changing the fluid will restore the cleaning properties of the ATF though, which may help fix shifting and temperature issues caused by buildup in the valve body. In the end, keeping the temperature down, which causes the failures to begin with, is why it is so important to change the fluid.

As Jerry and Chris said, complete myth.

 

[Jorge Bolivar]

Update for the benefit of the Google searchers.

We no just replace his 42RLE fluid, we do both LJ's. The fluid on mine was lot more redish color than on his, his LJ soak around 5.5 quarts while mine soak around 6.3 quarts. I have to say Wow! my Jeep runs lot more smooth now, His probably it is but he still scare of his tranny will be gave up on Him.
Now, I do install a transmission cooler in-line with the radiator on mine and notice the new temperature sender is just registering 160*. I do assume that I have some kind of loss between the Sender, wire type used and the gauge that may have the reading on the lower side by -/+ 10*.

Are 170* a good operating temperature for this Transmissions?

 

[Chris]

170 degrees sounds fine. However, a transmission cooler will never hurt. I am running the Derale 20561 transmission cooler on my 42RLE, and while I haven't monitored the temperatures, they are supposed to be 30-40 degrees lower than they would be without the cooler.

 

[glwood]

Update for the benefit of the Google searchers.

We no just replace his 42RLE fluid, we do both LJ's. The fluid on mine was lot more redish color than on his, his LJ soak around 5.5 quarts while mine soak around 6.3 quarts. I have to say Wow! my Jeep runs lot more smooth now, His probably it is but he still scare of his tranny will be gave up on Him.
Now, I do install a transmission cooler in-line with the radiator on mine and notice the new temperature sender is just registering 160*. I do assume that I have some kind of loss between the Sender, wire type used and the gauge that may have the reading on the lower side by -/+ 10*.

Are 170* a good operating temperature for this Transmissions?

Did you do it yourselves, or have it done at a shop?

 

[Jorge Bolivar]

170 degrees sounds fine. However, a transmission cooler will never hurt. I am running the Derale 20561 transmission cooler on my 42RLE, and while I haven't monitored the temperatures, they are supposed to be 30-40 degrees lower than they would be without the cooler.

OK, Thanks for the info @Chris
I decide to go with the Flex-A-Lite 4116TJ due the wheeling style around here in Ohio, many water passes and unexpected dunk tanks to jeopardize an expensive Derale unit. It's simple going to get pack with Mud or cooling fan motor blown due the water immersion.
I haven't tested on trails yet, let's see what happens this weekend.

 

[Jorge Bolivar]

Did you do it yourselves, or have it done at a shop?

Hi @glwood
We does it our self on my Jeep Garage at Home.
I'm proud of been performing 97% of all the work on my Jeeps especially the LJ.

 

[Chris]

OK, Thanks for the info @Chris
I decide to go with the Flex-A-Lite 4116TJ due the wheeling style around here in Ohio, many water passes and unexpected dunk tanks to jeopardize an expensive Derale unit. It's simple going to get pack with Mud or cooling fan motor blown due the water immersion.
I haven't tested on trails yet, let's see what happens this weekend.

I haven't had any issues with my Derale fan, but I wouldn't want to take it through water crossings or serious mud, I agree with you on that! It's a pretty expensive unit, that's for sure. It's great at idle in the city though!

 

[Shane Mckinley]

I’m having my leak fixed on my 42RLE now. DW so bad it put a hole in a line and dropped every bit of fluid I had Sun

I’ll likely go with a aux cooler soon myself.


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2005 RHD TJ Sport
2010 BMW 528xi

 

[Jorge Bolivar]

I’m having my leak fixed on my 42RLE now. DW so bad it put a hole in a line and dropped every bit of fluid I had Sun

I’ll likely go with a aux cooler soon myself.


Sent from my iPhone using Tapatalk
2005 RHD TJ Sport
2010 BMW 528xi

Glad you got that fix.
What was the DW root of cause?
It is many aux cooler options but the Derale Chris and Jerry Brandsford recomends and the Flex-A-Lite I do went with are Designed for our TJ’s and includes all you need to complete it’s install with very positive reviews.

 

[Shane Mckinley]

Glad you got that fix.
What was the DW root of cause?
It is many aux cooler options but the Derale Chris and Jerry Brandsford recomends and the Flex-A-Lite I do went with are Designed for our TJ’s and includes all you need to complete it’s install with very positive reviews.

Not 100% sure yet. So far steering linkage and upper/lower ball joints have been replaced. Checking track Bar next


Sent from my iPhone using Tapatalk
2005 RHD TJ Sport
2010 BMW 528xi