Late Game Transmission Fluid Change Rumors or Fact?

[nonickatall]

Two forms of deposits can form in a transmission. The first is abrasion of the pressure plates, which are made of steel.

This is very fine metallic abrasion that normally collects on the magnet in the pan.

The second is the friction lining of the friction disks. They have a similar structure to clutch plates in a manual transmission.

This is very fine abrasion that normally remains in suspension and is removed when the oil is changed.

It does happen that there is abrasion from the friction discs or mud in some corners. especially if you don't change the oil for a long time.

But these are usually very small amounts compared to an engine, for example.

In the attached picture for example you see a vent body of a Chrysler lebaron transmission. If you look very closely you see the small amount of deposit as dark shadows.

But thats it. From a flush, there can not be loosen deposit which damage your unit.

And again: The purpose of a flush is not to get dirt or mud out of the gearbox, but to get the oil out of all channels, oil pump, pistons, torque converter, oil cooler and so on.

 

[strutaeng]

The way I see it is this: the friction material is normally BONDED to backing plate and that's how it allows rotational force transmission with the aid of the clamping pressure. The "bonded" is what people forget here.

Once the material is knocked loose and is suspended in the fluid, it may as well just be a ball bearing. At least that's what picture in my mind are the mechanics of this. I don't see this "grit" being able to transmit any of rotational force anymore. There isn't even that much friction material in a single clutch once it's suspended like 12 quarts of fluid or whatever. Unless you have several clutch assemblies failing, then you have much larger issues.

Bearings, bushings, and races and other precisely machined surfaces are pretty much destroyed if enough clutch material circulates through them, as is the case of the TCC failure of the GM 6L family of transmissions.

I would simply say it's a coincidence that a transmission fails shortly after a fluid change, and those people believe in the old-wives tale to be true, which in their eyes, the fluid change is perceived as the event that caused the tranny to fail.

 

[S33k3r]

Two forms of deposits can form in a transmission. The first is abrasion of the pressure plates, which are made of steel.

This is very fine metallic abrasion that normally collects on the magnet in the pan.

The second is the friction lining of the friction disks. They have a similar structure to clutch plates in a manual transmission.

This is very fine abrasion that normally remains in suspension and is removed when the oil is changed.

It does happen that there is abrasion from the friction discs or mud in some corners. especially if you don't change the oil for a long time.

But these are usually very small amounts compared to an engine, for example.

In the attached picture for example you see a vent body of a Chrysler lebaron transmission. If you look very closely you see the small amount of deposit as dark shadows.

But thats it. From a flush, there can not be loosen deposit which damage your unit.

And again: The purpose of a flush is not to get dirt or mud out of the gearbox, but to get the oil out of all channels, oil pump, pistons, torque converter, oil cooler and so on.

Thank you for the explanation. Essentially, a flush is good for your transmission, unless it is already on the way out: i.e. If you have larger than expected particles in there already.

 

[89Suburban]

I use an extractor every 6 months to suck the pan dry and refill with new fluid.

 

[blackelky]

At this point I'd drain out what you can and save for a new or used trans

 

[denalilex]

I'm sure everyone has heard not to flush the fluid on a high mileage automatic transmission if you don't know the service history. Is this true?

Truck has 275k, bought it around 175k, 5.3 / 4L60E Z code. It's given me 100k absolutely trouble free miles other than the compressor just left the building, but rectifying that.

I have no idea the service history of the truck but it is absolutely 100% stock and more or less not ****** with. Transmission will stumble from time to time, funny shifts mainly, every once in a blue moon it will start in second. I would like to be extend the life of this transmission as long as possible, would new fluid and filter be advantageous, or should I flush? Neither?
Would love to hear some thoughts on this.

my trans just went @ 304k. i kind of expected it when i changed the fluid like a year + ago… imo, if you are concerned about the trans to the point of being weary of a fluid change - the problems are imminent & will eventually come. transmissions aren’t forever - like i said, mine went 304, it really sucks but at the end of the day, they’re only built for 150-200, i got beyond my moneys worth. just be prepared for it, i think a lot of this concept is mental because personally looking back - i decided on a fluid change because i figured it would help the transmission. there were already issues. this might not be your situation nor might anyone else agree with me & that’s ok.

mine went another year. i can not say that my fluid change caused its failure nor sped it up. i felt like it did improve. but i was at 210k already.


good luck.

 

[nonickatall]

my trans just went @ 304k. i kind of expected it when i changed the fluid like a year + ago… imo, if you are concerned about the trans to the point of being weary of a fluid change - the problems are imminent & will eventually come. transmissions aren’t forever - like i said, mine went 304, it really sucks but at the end of the day, they’re only built for 150-200, i got beyond my moneys worth. just be prepared for it, i think a lot of this concept is mental because personally looking back - i decided on a fluid change because i figured it would help the transmission. there were already issues. this might not be your situation nor might anyone else agree with me & that’s ok.

mine went another year. i can not say that my fluid change caused its failure nor sped it up. i felt like it did improve. but i was at 210k already.


good luck.

You are right, additional i would say:

If you take 100 similar transmissions.
50 never make an oilchange and 50 make regulary all 35.000 Miles an Oil change.

Then i guess 5 of the 50 without oilchange will survive 250.000 Miles.

And propably 25 or more of the 50 with oilchange will reach the 250k.

But there are additional factors which limit the life of a transmission, like permanent kick down, especially when cold.

Short distance drive profile. If you use the car in a big town to go too and from work, its more stress for the transmission, then when you drive only long distance on the highway with rare shift processes.

Or when you pull heavy trailers up the hill.

So the lifetime of your transmission can be extended by your driving behaviour/profile and frequent oil change.