OK I did transmission fluid flush on my 02 4.4i - Page 9

TwinTurboGTR · #1 08-11-2013, 02:39 PM

Quote:

Originally Posted by sunny5280

Consensus doesn't prove anything. I'm in the camp of changing the transmission fluid. I had it changed in my 2001 4.4i with 108K miles (right after I purchased the vehicle) and drove it to 129K miles before buying my current X5. Never had a hint of problem with it.

Consensus is always composed as a matter of opinion. Looking through threads, many on here have experiences problems after a fluid change, i.e. Trans fluid is a high detergent fluid, after a change, dislodges debris within the tranny. The debris could clog up passages for the fluid to circulate, starving the tranny of fluid in critical places. Is it 100%? No... it doesn't always happen and I am sure those who have changed their tranny fluid have experienced many miles of trouble free service and really don't voice the success. But those who have changed the fluid and experience failure, you can bet that they will always broadcast it.

While I agree fluid changes are necessary... I do not agree with having to spend a few hundred to change the fluid on a working transmission, then experiencing a failure and spending a few grand to fix it. Again, matter of opinion. If it ain't broke, don't fix it.

sunny5280 · #2 08-11-2013, 03:44 PM

Quote:

Originally Posted by TwinTurboGTR

Consensus is always composed as a matter of opinion. Looking through threads, many on here have experiences problems after a fluid change, i.e. Trans fluid is a high detergent fluid, after a change, dislodges debris within the tranny. The debris could clog up passages for the fluid to circulate, starving the tranny of fluid in critical places. Is it 100%? No... it doesn't always happen and I am sure those who have changed their tranny fluid have experienced many miles of trouble free service and really don't voice the success. But those who have changed the fluid and experience failure, you can bet that they will always broadcast it.

While I agree fluid changes are necessary... I do not agree with having to spend a few hundred to change the fluid on a working transmission, then experiencing a failure and spending a few grand to fix it. Again, matter of opinion. If it ain't broke, don't fix it.

In theory the explanation makes sense. However there have been nothing but anecdotes to support such a thoery. We don't know all the details that go into each anecdote. For example it's not unlikely someone was experiencing a transmission issue and decided to try changing the fluid in an effort to correct it. Instead masking an underlying problem. Until there is support data it remains nothing more than theory.

JCL · #3 08-11-2013, 03:24 PM

Quote:

Originally Posted by sunny5280

Consensus doesn't prove anything.

Completely agree.

But I would respectfully point out that consensus implies a large sample, and you are holding your example out as proof to the contrary, in a case where n=1.

I would not expect you to have had a problem after changing your fluid, as more transmission will be fine post fluid change than will fail. But we are discussing the risk of failure, statistically, not whether they will all fail. And on the other side of the coin, you don't know that your transmission wouldn't still be running fine with the original fluid. You spent the money, got no return on that investment, and arguably increased your risk. Is that an investment decision you recommend all should make?

sunny5280 · #4 08-11-2013, 03:49 PM

Quote:

Originally Posted by JCL

Completely agree.

But I would respectfully point out that consensus implies a large sample, and you are holding your example out as proof to the contrary, in a case where n=1.

I would not expect you to have had a problem after changing your fluid, as more transmission will be fine post fluid change than will fail. But we are discussing the risk of failure, statistically, not whether they will all fail. And on the other side of the coin, you don't know that your transmission wouldn't still be running fine with the original fluid. You spent the money, got no return on that investment, and arguably increased your risk. Is that an investment decision you recommend all should make?

No, I am holding the 25+ years of experience of my indy mechanic as evidence. As I said he worked for a local BMW dealer for 25+ years. In his experience he has not observed any correlation between changing the fluid and subsequent failure.

Likewise I have seen no supporting data anywhere to support this theory. If you've got some hard data I will be happy to take a look at it and reconsider. Until such time all we have are a number of anecdotes that form the "consensus". There could be any number of reasons for why a transmission failed after a fluid change. The most obvious being it was done incorrectly (which could be reason enoug to avoid doing it). It's not uncommon for work to be performed in an incorrect manner with problems as a result.

JCL · #5 08-11-2013, 04:01 PM

Quote:

Originally Posted by sunny5280

No, I am holding the 25+ years of experience of my indy mechanic as evidence. As I said he worked for a local BMW dealer for 25+ years. In his experience he has not observed any correlation between changing the fluid and subsequent failure.

Likewise I have seen no supporting data anywhere to support this theory. If you've got some hard data I will be happy to take a look at it and reconsider. Until such time all we have are a number of anecdotes that form the "consensus". There could be any number of reasons for why a transmission failed after a fluid change. The most obvious being it was done incorrectly (which could be reason enoug to avoid doing it). It's not uncommon for work to be performed in an incorrect manner with problems as a result.

We've had this discussion many times before Sunny, and I am not out to change your mind. You have your mind made up. Fair enough. All of the posts that we provided to you documenting transmission failures post fluid change on past threads, you discounted as "probably a coincidence" and "anecdotal".

The outstanding question is, didn't you have to replace your own transmission valve body? You posted and described that in some detail back when it happened. I remember the references to your trusted independent mechanic, and a thread about your own transmission fluid change. I can't link to those discussions, because unfortunately the threads were subsequently edited. Perhaps they were leading to reader confusion about coincidences and anecdotes.

Any comment?

jsoto · #6 08-10-2013, 09:31 AM

Just wanted to add this to the wikipedia.
For me, ZF5HP24.
3 Bolt Drains/Refill.
1 Pan Drop, NO Filter Change.
Fluid was cheap for me.
No issues up to this point.
Note, I have been experiencing the 2/1 downshift when I approached 98K miles, but this happened more/noticeable when I was on a incline and in stop and go traffic bumper 2 bumper rush hour traffic.

Full Pan Drop, filter, line flushed - I think I used about 11.25 qts .
The 2-1 downshift magically went away !
2500 miles later, G1 started slipping on me. 2 minor times with a hard bang into gear, then later in the day, straight slip until it hit 2nd gear with a hard bang and then limp mode, 1 stop sign away from home.

I did not hesitate going with the rebuild..
She's running strong. I'm still putting it through it's paces but sofar, sogood.

Hoser · #7 08-10-2013, 02:39 PM

Yes after I posted I looked at the previous posting dates and realized I should go to bed. One technique for changing out tranny fluid owners of large RV developed was to, change out filter, then undo the return line from the tranny cooler and drain into a bucket while filling with new into the other return line section-with help from someone idling the car while this oil change circus is going on. It at least allowed the closest thing to 100% oil change. This involved transmissions with 18 to 25 liters capacity-but it is just as important for our cars. Anyone ever put forth this changeout technique?