New ATF in a bad transmission.

[dave1251]

Why do mechanics often assume because a transmission has been recently filled with new ATF, this is what caused the transmission failure? Do mechanics assume that recently changed motor oil caused engine failure? Because of this ignorance I have heard mechanics tell customers that they recommend not changing ATF. Needless to say I will not recommend someone use those mechanics in question. I tired to ask the mechanics that do not recommend ATF service that the ATF should be changed more to avoid the transmission failure but many are just plain stubborn.

 

[rshaw125]

I think it's because a fluid change is done as a last resort. Then they assume cause and effect.

 

[SteveSRT8]

All of us have some old pre-conceived notions that need some revamping to come into the new millenium.

I have found so-called "mechanics" to be embarrassingly inaccurate more than once.

And if you run a shop and you replace transmissions why would you want them to last?

 

[Maritime Storm]

Changing the lfuid in a higher mileage unit isn't what usually kills them, chemical flushes are the usual culprits in a transmission that failed after a recent flush and fill.

 

[Towncivilian]

A mechanic at my local AAMCO owns a 2003 Pathfinder with 186k+ miles on it and is still running the factory fill of ATF. I suggested that he change it but he said it's been too long and it'll fail if he changes the fluid. I don't remember his reasoning though. He said he'll just wait for the trans to die. I found it ironic that he is employed at a transmission shop yet does not maintain his own vehicle.

 

[bdcardinal]

They don't want the liability if the unit goes south. People that tend to neglect the fluids in their car and wait til the last possible minute thinking new fluid will be the panacea. Then when the trans dies the next week it is of course the shops fault.

 

[vinu_neuro]

It is true. Some transmissions are particularly sensitive. BMW's come to mind. There are enough of such failures on those boards. Unless you replace all the atf regularly there will be deposits, and those do get dislodged, either through the drain/refill or replenished detergents in the new fluid, and end up in a bad place. I did a quality engr internship at a hydraulics mfr sometime ago, and having looked at modes of failure it is incredibly to make the relevant components fail through contamination.

 

[Bgallagher]

Originally Posted By: Towncivilian
A mechanic at my local AAMCO owns a 2003 Pathfinder with 186k+ miles on it and is still running the factory fill of ATF. I suggested that he change it but he said it's been too long and it'll fail if he changes the fluid. I don't remember his reasoning though. He said he'll just wait for the trans to die. I found it ironic that he is employed at a transmission shop yet does not maintain his own vehicle.


It's the same reason why painters hate painting their house. I believe there is some truth to it. If you havent changed your ATF in over 180k then fresh fluid might dislodge some crud or do something to cause damage. If the fluid actually causes any issues then you were sitting on a ticking time bomb. I change my with a drop and fill every other year. My SUV takes roughly 4 quarts a drop. It's cheap insruance!

 

[Lead Shoes]

Originally Posted By: Towncivilian
A mechanic at my local AAMCO owns a 2003 Pathfinder with 186k+ miles on it and is still running the factory fill of ATF. I suggested that he change it but he said it's been too long and it'll fail if he changes the fluid. I don't remember his reasoning though. He said he'll just wait for the trans to die. I found it ironic that he is employed at a transmission shop yet does not maintain his own vehicle.


I may work at a restaurant, but I don't like to cook my own food off the clock, I probably wouldn't want to get wrist deep in my car after working a full shift wrenching on other peoples.

I changed the ATF on my old 3.4 Grand am when the transmission was starting to slip and shift sloppy, the pan drop and filter change was the best thing for it, I sold it to my friend and 30k later it is starting to show signs of it dying at 180k, I told him to try the fluid change to see if it helps, but hes just going to let it go. But considering I don't think the ATF was changed but once before I did, it lasted a lot longer than the week most mechanics say it will.

 

[JR]

i am a mechanic if it has over 100k i will not change fluid if a customer wants it i send them down the road to a friends shop for filter and fluid and my advice is dont do it but if you do good luck it can and 98% of the time will fail or have permament damage.

kc

 

[Donald]

Originally Posted By: JR
i am a mechanic if it has over 100k i will not change fluid if a customer wants it i send them down the road to a friends shop for filter and fluid and my advice is dont do it but if you do good luck it can and 98% of the time will fail or have permament damage.

kc


Neither of my vehicles have less than 100K.

 

[Smokescreen]

The very high mileage AT that is running original or very old ATF will fail at some point, its just a matter of time. The mechanics have no idea how far gone the transmission is when it rolls into their shop. When it does fail, the last one to touch it is usually blamed and is going to have to compensate, that cost of compensation will always be way more than they would've made on the ATF change. Its just down to bean counting and they are just managing their money.

Whether or not it failed because the new fluid cleaned out some gunk is secondary.

Regular maintenance really pays off. On my Suburban it shifts like new and I tow every other month it seems 3500-5500 lbs. Once a year it gets 1/2 capacity drain/refill

 

[MolaKule]

Quote:
A mechanic at my local AAMCO owns a 2003 Pathfinder with 186k+ miles on it and is still running the factory fill of ATF. I suggested that he change it but he said it's been too long and it'll fail if he changes the fluid. I don't remember his reasoning though. He said he'll just wait for the trans to die. I found it ironic that he is employed at a transmission shop yet does not maintain his own vehicle.
That's nuts. It is so easy to do drain and fills on this Nissan vehicle because of the tranny pan drain bolt. Drain and refills keeps the additives fresh, avoids valve and piston varnishing, and in general helps remove any clutch particles that might cause problems.

 

[MolaKule]

Quote:
Changing the fuid in a higher mileage unit isn't what usually kills them, chemical flushes are the usual culprits in a transmission that failed after a recent flush and fill.
Exactly. Changing fluid every 30k allows a slow cleaning. Using a flush or solvent dislodges partcles and varnish at once. If I were a mechanic at a shop and some dingbat wanted a fluid change for a tranny that has never had a fluid change, I would do it but write up a statement for the customer to sign that says this fluid change will not cure any current or future problems due to maintainnace neglect. This way you do what the customer requested, but you CYA in case this character wants to take you to court when the tranny fails.

 

[RF Overlord]

I am SO glad to see this thread. Every board I belong to has some numbskull come on and proclaim that changing the ATF is a death sentence. I try to set them straight, but it's like convincing people Pennzoil doesn't cause sludge...they always know some guy whose father's barber's gardener's uncle knows a mechanic who once talked to a guy whose transmission died backing out of the shop after changing the fluid.

 

[tommygunn]

Originally Posted By: RF Overlord
Every board I belong to has some numbskull come on and proclaim that changing the ATF is a death sentence.


Yeah I'll have to agree, this thread is nice to see people with some informed insight into the assistance they give as opposed to telephone tag of biased opinion.

But I also agree; if a car was sludged up and already knocking really bad would you suggest an oil change? No. Because you know the engine is screwed anyhow and a person is probably wasting their time, and if it blows up a week later you'll probably get blamed for it (because it was "just fine" before you said it was sludged up).

Transmissions probably the same thing because almost everyone I know NEVER services their transmissions and drives it for ages upon ages as it slips and grinds funny. Usually by the time they're looking for options the transmission is so beyond a good fluid change to fix it that the transmission will inevitably explode anyhow.

But I guarantee there is a lot of people guilted into euthanizing their transmission because someone said not to change the fluid.

 

[SwampSurvivor]

I've had people tell me that a transmission fluid change on a low mileage vehicle is just as bad ... even though it was in the owners manual.

People just don't maintain cars and stuff fails when it fails. Unfortunately for too many people, everything happens at once.

A friend of mine with a Hyundai Santa fe had bad surging between 2 and 3. Once I sucked out the fluid, I could easily tell it was the factory fill.

What do I do at this point? The transmission is acting up and on its way out. It could blow up tomorrow or it could go another 40k miles. I let him know that the transmission was on its way out and this was just a stop gap to get a few more months out of it.

We'll see how it goes.

I change the trans fluid every oil change on the Cherokee ... cheap insurance.

 

[SS1970chrysler]

About every 50k miles, I pump out a gallon and replace it. At 100k miles, I drain and change filter. Except for 200R4's; never had one last to 100k.

 

[JZiggy]

I heard an argument once that an old, worn out AT will have substantial amounts of wear particles in the fluid which act as a kind of friction modifier allowing the clutches to still do their thing. Putting in fresh fluid then causes it to slip. Of course, with no maintenance it was on its way out anyway...

 

[SS1970chrysler]

Originally Posted By: JZiggy
I heard an argument once that an old, worn out AT will have substantial amounts of wear particles in the fluid which act as a kind of friction modifier allowing the clutches to still do their thing. Putting in fresh fluid then causes it to slip. Of course, with no maintenance it was on its way out anyway...


I did have something like that happen on my '76 Impala. After changing fluid, it would jump back and forth between 2nd and 3rd until it really warmed up. Took 2 months for this to go away. Car was perfectly fine after that and drive for several more years.