Automatic Gearbox fluid replacement

Auto Transmission Fluid Change

I have searched through my 8-Series archives and I found this article........ I do not recall its origin or the date I'm afraid (file date is 29-3-2007, but that's when it went on my system, not the actual date of writing).

Usual acknowledgement to the author of course, Jim Cash who made this public some time ago.

I have reproduced it here exactly as I received it with no changes or alterations (even to spelling).

The Article was Titled "Transmission Fluid...change...NO NO NO.doc"

8-Series Transmission Fluid - to change or NOT.


Just when you thought this one had died down for a while someone raises it again - here goes.

Like many of you I have wondered/worried a bit about this "life time fill - no change" issue.

There are some experiences, and lots of opinions being expressed. When faced with that I usually try to go back to industry sources, give them what I am hearing and see what they say.


In this case I conferred/conversed with:
- My service manager (although experience limited to what he sees I value his honest input)
- The BMW Canada senior technical engineer (liason to Germany)
- An engineer at ZF who was involved with the development of the lifetime fill fluids.

To keep this simple the following is a point summary of input/advice.

- Service Manager was originally willing to change my fluid when I asked several years ago, but now he "highly recommends that I NOT do it". They have done it on a couple of 7's (with lifetime fluid units) and have encountered some evidence of slippage. They have had no known failures of lifetime fill transmissions that they could attribute to a deterioration in the fluid.

- I also discussed this with the BMW engineer some time ago, and he had similar advice that I got from my Service Manger - basically that it was up to me but he recommended against it because they had no eveidence to say that leaving the fluid was causing any problems.
Now I had been sending some of the info I was finding on the varios message boards to my Service Manager (for interest) and apparently he was forwarding them to the BMW engineer. Two weeks ago the BMW guy called my Service manager and said to "Tell Jim not to change his fluid" - the current experience is that they are seeing more problems in transmissions that have had fluids changed than those that have been left alone.


- Regarding the ZF engineer I sent him an email summarizing many of the comments and questions that I have seen on the message boards, and asked his opinion.
Following is his reply.

1.) The life time fluid was introduced in 1995 to save costs for the customers and to reduce environmental pollution. The fluids are tested and released for a lifetime which is specified by the car manufacturer. A change of the fluid within that span is not necessary.

2.) If you intend to change the fluid (even though I believe it is not necessary), it is a must to use only the fluids which are specified on the labels placed on the bottom of the transmission oil sump. Please note that these fluids have BMW part numbers and are available at BMW service only (For the 5HP30 there are two different fluids in service, the appropriate one depends on the MY of the car, please refer to the labels).
Please note that fluids acc. to Dexron III spec, which are in current use for other transmission manufacturers, are not specified for lifetime fill in ZF automatic transmissions. A use of non specified fluids will cause unexpected transmission behavior as described in your mail or a complete transmission damage.
Also please note that a single oil change does not replace the whole amount of oil within the transmission, it will be necessary to drain and refill approximately 3 times to completely change the oil.

--
I then asked specifically if changing the fluid could, in itself, cause any transmission damage.

Response.
Jim,
it's correct, you cannot make your transmission worse by changing the fluid as long as the specified proper fluid is used and the refill is carried out correct (especially the procedure to adjust the oil level - this is critical and can really only be performed accurately with the car connected to the diagnostic system).
But there is no relation between the number of drainings and refillings and the statement above. It was an additional hint that a **complete** change can be achieved only by draining and refilling at least 3 times.

-----

Soooooo

Based on all the above my conclusions are:

- don't bother changing (I am not going to)

- but if you do, you have to get ALL the fluid changed (draining and refilling 3 times can be real expensive with that fluid)

- you have to get the level correct - and that is done with the car running and with the transmission fluid at a specific temperature (as read by the system)


Yes, more questions come to mind, especially about the methods or total replacement of the fluid. While some places use special tools to get additional fluid out, all the input I have from the dealer, and ZF say that, without taking the transmission off the car, you can not get the old fluid out of the converter without repetitive drainings and refils.


Summary

Both BMW and ZF are saying the transmission fluid should last the lifetime of the car. And they are recommending against changing it.

And ZF is saying that if you do change it for any reason - you had better do it correctly.

So the real question is "what is the expected life time of the car"?

I have not asked BMW that one, and I am not about to since I suspect the issue is too complicated (depends on a whole bunch of issues - many of which are beyond BMW's control) to get a meaningful answer.

So for what it's worth - that is the information I have pulled together. I am not changing my fluid but you can bet that if my unit ever goes south I will have it analysed - and out will come some of this documentation as part of the negotiations on pricing of the fixit bill.

Cheers
Jim Cash

Change gearbox fluid

Yupp, I changed all fluids, including the gearbox fluid when bought mine a year and a half ago.

Planning on doing a change before the summer season next year, since one change does not completely drain all the fluid in the box.

I've heard you're supposed to change at least three times in order for most of the old fluid to get out.

Edit: Mine is a 1991 and has probably not "lifetime" fluids.

/Hannes - from a cold and rainy Sweden

Zitat von David8;57312

So the real question is "what is the expected life time of the car"?

Indeed. Ask a German ZF engineer and he will tell you that this is around 150k kms or 100k mls.

It is important to know that wrt E31 the "lifetime filling" applies only to auto M60/62/73 cars as they are the ones with ZF 5HP30 5 speed gearboxes.

Judging from stories originating from E34 and E38 boards even a half or 2/3 oil change along with the gear box oil filter and a little cleaning can make a difference like day and night so don´t be lured into believing you cannot do anything at all.

ZF in Dortmund/Germany offers a full gearbox oil service which also includes removal/cleansing of the control valve assy and the replacement of a number of nylon balls that open and close the valve channels. Cost is approx 300 EUR.

Oil in ZF 5HP30: there are actually two types of oil for the 5HP30. One is the ESSO LT71141 and the other one is a Shell LA2634 (NLA but compatible with ZF Lifeguardfluid 5). The reqd oil is determined by either the colour of the sticker on the gearbox (very early ones with black sticker only need DEX III spec oil) or to be sure by the gearbox part number. The correct (and published) procedure needs to be followed in order to not _underfill_ the gearbox.

Oil in 4HP gearboxes: all M70 based E31 cars with auto gearbox have a ZF 4HP24 gearbox. This gearbox does have a dipstick and inspection requirements exist!
The BMW inspection plan includes a gearbox oil change (3,5L) every Inspection II which for most people corresponds to 40-50K kms or roughly 30k mls.

Today ZF has moved to using the ZF Lifeguardfluid 5 instead of the ATF fluids even in the old 4HP gearboxes. Maybe after all it is not such a mystery science as they made us believe for the last years.

Cheers
Reinhard