ATF change question

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Is it real the myth about replacing the ATF after certain number of miles driven on the same fluid, will damage the transmission? I'm very much aware about many people saying it will hurt the transmission, but have you seen any case of a vehicle with a broken transmission caused but an ATF replacement?
 
If you change the fluid and the transmission dies, the transmission was going to die any way and was living well past borrowed time.
 
I personally haven't had a transmission fail due to a change, and I've done the first change on a new-to-me vehicle with up to 85000 miles. Definitely avoid a flush on a higher mileage vehicle, but a pan drop, filter and refill should be fine IMO. YMMV.

But...what vehicle and what mileage are we talking about?
 
Originally Posted By: Carguy21
Is it real the myth about replacing the ATF after certain number of miles driven on the same fluid, will damage the transmission? I'm very much aware about many people saying it will hurt the transmission, but have you seen any case of a vehicle with a broken transmission caused but an ATF replacement?


I think that would only apply if you replaced the existing ATF with an incorrect new fluid. An example would be using dexron on a Chrysler tranny that needs ATF+4.
 
Originally Posted By: Carguy21
Is it real the myth about replacing the ATF after certain number of miles driven on the same fluid, will damage the transmission? I'm very much aware about many people saying it will hurt the transmission, but have you seen any case of a vehicle with a broken transmission caused but an ATF replacement?


Its a myth with a little bit of basis in fact. Old fully-hydraulic transmissions could take a lot of abuse and keep working. They could work with huge internal leakage past seals and valves. On rare occasions, fresh fluid (being un-oxidized, uncontaminated) would leak past a bad seal *just* enough faster than the old fluid so that the transmission wouldn't go into gear once the new fluid got circulated. It was worse when cold, so sometimes the car would drive home from a fluid change and then not move the next morning when all the seals were cold and shrunken. People then blamed the fluid change. But in reality, the transmission was a dead man walking even before the fluid change.
 
How many miles on it now and what engine does it have? I'd do a simple drain and fill every 30k miles unless it's a sealed unit.
 
Originally Posted By: Carguy21
Thanks for the answer, I'm talking about a 2013 Kia Optima 2.4
I bought it with over 50,000 miles on the odo.


50k is an ideal time to change the ATF fluid.
 
Originally Posted By: Miller88
If you change the fluid and the transmission dies, the transmission was going to die any way and was living well past borrowed time.
This.

Originally Posted By: 440Magnum
People then blamed the fluid change. But in reality, the transmission was a dead man walking even before the fluid change.
And this.
 
You may not find a shop wanting to change the ATF in a high mileage vehicle as they do not want to hear it should the transmission fail. While changing the ATF has no effect on a transmission failure, if the transmission was in rough shape already then a shop might pass on changing the ATF.
 
This is a myth perpetuated by the simple fact that a transmission shop does not want to earn a new enemy over performing a low-profit service, who will almost certainly blame them without understanding that their transmission was dead anyway.

The solenoid pack in my auto Ram's transmission STB after doing a complete fluid exchange. It happened because these solenoid packs are well-known turds. I know this, and so does anyone who does half a minute of research. A standard consumer would have been ready to play the blame game. I knew better.

There is also a failure to understand that Sonnax has proven that the appearance of solids skyrockets after a transmission fluid pan drop or complete fluid exchange.

If your transmission has been out there a long time without receiving a fluid change, an add-on filter is a very recommended way to make sure your trans stays healthy after it gets a complete fluid exchange.

I have done fluid exchanges on transmissions that had not seen one in 150k miles. I added external filters or changed factory external filters at the same time (and changed them after 10k miles) and have not seen any sort of transmission problems on those same transmissions over 100k miles later.
 
Originally Posted By: DoubleWasp
... an add-on filter is a very recommended way to make sure your trans stays healthy after it gets a complete fluid exchange.


When adding a filter, especially an external one to a unit which wasn't designed to take this into account, is there any risk of missing with the flow or causing slight delays in fluid delivery? how do you determine the size, flow rate and bypass setting to go with if there are no original specs to begin with?
 
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Originally Posted By: DoubleWasp
Even a good-sized transmission cooler is a far greater restriction than any external filter is. Last thing I would be concerned about.

Do you add some extra ATF whn you run a Trans cooler? And is so is there a rule of thumb as to how m ,uch to increase it by?
 
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Part of me cant help but wonder if another reason for this myth was because the wrong ATF was used.

Not the ATF or transmissions fault at that point.. Many many folks think store brand multi vehicle fluids are universal.
 
I run both a remote filter - Derale mount + Fram XG16 (Ultra) and add on cooler - it is TruCool LPD
(Low pressure drop). Strongly recommend Gates hoses.
Maybe adds a quart to system - just do pan flips (5 quarts) since I have a drain plug. Fast/clean.
 
I was actually referring to OEM transmission coolers, but if I am adding one, I always refill the trans to proper level. The fact that some is lost in the installation is as much a factor as anything.
 
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