# Lifetime Automatic Transmission Fluid Conundrum Solved Once and for All



## edsu (Jun 3, 2015)

Hi BMW Owners,

This transmission fluid conundrum applies to all BMW series. You and I have read way too many threads arguing whether the "Lifetime" automatic transmission fluid (ATF) needs to be changed or not. As a professional mechanical engineer, I decided to look for a scientific answer straight from the source: ZF company, the manufacturer of BMW transmissions. As of 2013 nearly all BMWs (1-7 series) use the ZF-8HP transmission. The following case study is for my vehicle F30 335i which uses the ZF-8HP45 model [Ref. 1], but the info applies to any other series as well. References are provided at the end of this writing if you want to confirm them yourself.

A data sheet for 8HP45 as published by ZF specifies the transmission oil as "lifetime oil fill" [Ref. 2]. Other models such as 8HP70 for the 7-series and X5 also repeat the same statement. Being a true scientific researcher, I was not satisfied with this statement because everything in this world will degrade and fail. The question is not if, but when. So I went on to research more into the ZF lubrication fluids and discovered that they manufacture variants of transmission fluids. In the case of automatic transmissions for cars including the 8HP models, the fluid is part no. TE-ML11 [Ref. 3]. A straight copy and paste from the datasheet regarding maintenance states:

"... automatic transmissions are filled maintenance-free with specially developed partially synthetic ATF oils. Maintenance-free fills are intended for normal operating conditions. Especially driving at very high operating temperatures can result in accelerated aging or increased wear of ATF oils. It is recommended, in the event of severe operating conditions, such as:
- frequent highway driving in top speed range,
- offensive, sporty driving style,
- frequent trailer operation,
being above average, oil purification (oil change) on automatic transmissions is recommended between 80,000 km and 120,000 km, or 8 years, depending on the load."

Based on the ZF's data sheet, it is clear to conclude our discussion with the following points:
1) The ZF ATF was designed to last beyond 120,000 km or 8 years if you drive under normal operating conditions.
2) Changing the ATF is allowed and will not result in damaging the transmission unit as long as you use the correct ZF fluid.
3) You don't have to be ripped off by buying the ATF from a BMW stealership, the ATF for 8HP models is ZF Lifeguard Fluid 8 (ZF No. S671 090 312) and it's available online.

You can search for the specific model of your transmission online and find the required fluid from [Ref. 3]. I attached the PDF for your convenience. I hope this post resolved our doubts and misconceptions.

References:
[1] F30 Technical Data, <http://f30.bimmerpost.com/forums/showthread.php?t=643183>

[2] ZF 8-speed Automatic Transmission Technical Information, PDF format, <http://www.zf.com/corporate/en_de/products/product_range/cars/cars_8_speed_automatic_transmission.shtml#tabs1-1>

[3] ZF List of Lubricants, TE-ML_11, PDF format, <http://www.zf.com/corporate/en_de/products/spare_parts/technical_information/lubricants/lists_of_lubricants/lists_of_lubricants.jsp>

New Update:
New statement from ZF's website below: (http://www.zf.com/corporate/en_de/a.../faq_oil_change_kits/FAQ_oil_change_kits.html)
"Regular maintenance intervals will increase the automatic transmission's service life. ZF recommends a regular oil change at between 80 000 and 100 000 km or after 8 years depending upon the stress."


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## crazy4trains (Mar 30, 2011)

Just change the friggin fluid!!!


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## tim330i (Dec 18, 2001)

Great post!


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## eeyore8 (Nov 19, 2014)

Can you post this doc:
[2] ZF 8-speed Automatic Transmission Technical Information, PDF format


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## hankdkrank (Apr 24, 2015)

Good job.


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## Dave 20T (Apr 7, 2013)

Great post! So it answers the question. It is long life fluid but not lifetime. For an average driver, change it after 120,000 km or 75,000 miles or 8 years. Maybe a 100,000 mile interval is ok?


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## edsu (Jun 3, 2015)

eeyore8 said:


> Can you post this doc:
> [2] ZF 8-speed Automatic Transmission Technical Information, PDF format


I attached all the pdf's with the links to find them on my original post. I think the forum's moderator deleted them for some unknown reason. If it is a copyright issue I'm pretty sure I have referenced them properly.


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## edsu (Jun 3, 2015)

Dave 20T, 
I do not have a scientific answer to this question, but my engineering judgment would lead me to change the fluid every 5 years just because of oxidation and moisture contamination. Mileage wise it makes sense to me to change initially at 70,000 miles to remove the metal shavings generated during the "break-in" period and then every 5 years. Make sure you buy the ZF fluid I mentioned above.


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## Road (Mar 27, 2015)

Thanks edsu, it's refreshing to see scientific fact rather then opinion or antidotal evidence. 

Paul


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## stonex1 (Oct 10, 2012)

edsu said:


> Dave 20T,
> I do not have a scientific answer to this question, but my engineering judgment would lead me to change the fluid every 5 years just because of oxidation and moisture contamination. Mileage wise it makes sense to me to change initially at 70,000 miles to remove the metal shavings generated during the "break-in" period and then every 5 years. Make sure you buy the ZF fluid I mentioned above.


+1

I would add that if you ever encounter some deep water driving (say, heavy rain storm) and you pass through some deep road puddles, check your powertrain oils more often.
Water is a killer if it gets into your diff fluids.

BMW does a good job of protecting the powertrain components, and hopefully the breather vents are protected, but this can be a common issue with trucks that launch boats in and out of water.


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## marcozandrini (Feb 13, 2014)

"Lifetime fluid" means that the fluid will last until the tranny blows up. I've never owned an automatic tranny (never will) but have always changed the gear lube annually with Redline MTL. These trannies have always shifted properly.

As someone wrote above, change the fluid. Please remember that draining/refilling the fluid leaves about 60% old fluid in the tranny. The only way to get all of the fluid out is to rebuild it.


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## J308 (Dec 10, 2011)

edsu said:


> 3) You don't have to be ripped off by buying the ATF from a BMW stealership, the ATF for 8HP models is ZF Lifeguard Fluid 8 (ZF No. S671 090 312) and it's available online.
> 
> You can search for the specific model of your transmission online and find the required fluid from [Ref. 3]. I attached the PDF for your convenience. I hope this post resolved our doubts and misconceptions.
> 
> ...


Thank you for this post. Dealer wants $1K for a drain-and-fill.

Now I just gotta figure out if my 2011 X5 8-speed is the same transmission cited here as the '13.


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## jburke4689 (Apr 9, 2008)

I know this is an old thread but my post is still relevant. My first BMW was a 2007 335i 6 speed manual. It also had lifetime fluid. I called ZF and talk to a tech support engineer to find out when I should change it. At first he hesitated to deviate from what BMW claims. Then he said, "is it out of warranty?" I said it was and then he said "change it."


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