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Transmission Fluid: To change or not to change....that is the question.

2109 Views 4 Replies 5 Participants Last post by  mike1967
Not just auto Minis, but all autos...

Two schools of thought:

1) It's working fine, leave it alone. You're asking for problems if you start playing with it.

2) "Fluid for life", yeah right, change it!

On the second one, one thing I was surprised by is many people seem to change just the fluid and not the filter. Seems to me like you'd want to do both.
Then there is the method. Since you can't drain the torque converter, some change the fluid, drive for a while, then change again, even a third time of the fluid is still dark. Where you would change the filter in that process is interesting..


2011 Countryman 160K

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I think the main reason people are steered away from changing it is the potential to disturb debris or particles or pressures etc that can affect operation, the dealers seem quite adamant it's lifetime, personally I've always been of the opinion it's far better changed, a caveat being changed 'more often' perhaps, or the owner take the risks of loss of function or change in characteristics at least, that they might not like. One cannot see inside and one cannot undo/reverse the job once requested ;O)

Transmission ECU's adapt as do engine, and they communicate, so there is potential for some degree of affect imo. I personally wouldn't be deterred but on a car of my own perhaps more than a customers, especially one looking to have it done for the first time at this mileage, it's likely to exhibit a greater difference in shift characteristics than one having had it changed twice before for example. Only my own view, no reason not to do it, just food for thought perhaps. I have seen instances where a symptomatic transmission has had a fluid change and deteriorated after, this is not the same as routine on a fault code free fully functional system, just saying that stuff happens.

Fwiw in the last scenario I'd change the filter in the final change. Some car models might need to run the motor while pumping fluid through to flush a torque converter, haven't had to do it personally, some Mercedes for example, whether anyone's done it on something like this who knows. I'd opt to change it a couple of times, and did actually on my 172k CL500 when I got it, wasn't that bad in colour really but wasn't clean and the pan had a sediment film on it hence done again a few months later just because....

If it misbehaves after changing I would look at an adaption reset, then use it for a while to see how it settles.
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˄THIS˄ on high mileage transmission that has never been changed, changing it can cause problems than just leaving it alone.

Different story if it has been changed regularly say every 60/70k miles or whatever interval people use.
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It's not really a transmission FILTER. It's a scouring tray with a trap type system.
I have all the stuff to change my fluid my fluid in my transmission including the powerfill air pressurized tank with air hose valve for a compressed air. I just have the actual nozzle size for the fill port on top of the transmission just past the transmission cooler.
I also have the new scouring module if or FILTER as it is sold as. The warning label sure is scary to read; on a off not.
changing oil on auto box that has no faults with it tends to be ok thinking changing oil on a car that has started to jump gears and leak oil dont tend to go that well ie the debris makes up the grip lost from worn plates , stopped buying anything with a auto box years ago as see many with issues before 100k ,, Mercedes are one of best or if not the best auto box out there all the psa offerings are terrible even honda's i shift is not much better ,,, vw DSG gearboxes also have a long list of fails from electronics to cracking its filter housing inside the box,,, i find my left leg and clutch pedal can do a better job than a gearbox that has a mind of it own and cost so much more to repair
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