The trend in the automotive industry (and this is not just BMW, but every manufacturer) has been to increase service intervals to reduce the cost of ownership artificially. The issue with this is those intervals have been proven to be detrimental to the long term reliability and service life of the vehicles in question. This is the case with BMW's 6HP and 8HP automatic transmissions.If you weren't aware, BMW does not manufacture their transmissions. Instead, General Motors and ZF are the two major suppliers for automatic transmissions for BMW vehicles. Both of these transmission manufacturers have their own specific service instructions on how their transmissions should be maintained, and we should, and do, trust the information supplied by these companies who've engineered and developed these transmissions over the vehicle manufacturer.
ZF 6HP & 8HP Automatic Transmissions
Here at FCP Euro, we have an extremely close relationship with ZF, who is the supplier of 6HP and 8HP transmissions to BMW. BMW rates these transmissions for a "lifetime fill," however, through our channels at ZF and speaking with the engineers of those transmissions, we've learned that the transmissions are tested to 100,000 miles with an "acceptable rate of failure" on the original fill. 100,000 miles is BMW's definition of what a "lifetime fill" and that's passed the extended warranty and "good-will" repair limit, meaning a failure after that is no longer BMW's responsibility. In the case of the 6HP/8HP, ZF actually has a published service interval for those transmissions which completely contradicts BMW's service information with an interval of 8 years/80,000km (~50,000 miles). This information supersedes BMW's "lifetime fill" rating.
GM 6L45 & 6L50 Automatic Transmissions
BMW vehicles equipped with the GM transmissions, which BMW designates the GA6L45R and GA6L50R (GM designates them as the 6L45R and 6L50R) GM's own information on this transmission contradicts BMW in how this transmission should be serviced. Every GM vehicle that uses a 6L45 or 6L50 transmission has a service interval under 45,000 miles. Keep in mind the internals of these transmissions, including the Mechatronic unit, solenoids, and everything else, are all the same between the BMW and GM platforms as it's a modular transmission. With that said, 45,000 miles falls in line with the average automatic transmission service interval specified for both ZF and GM from their engineering departments.
So why am I being told my transmission is "lifetime fill"?
If you're wondering why a service adviser at a BMW dealership would inform you that the transmission is a "lifetime fill" and doesn't have a service interval the answer is simple—they don't know any more than what their computer screen is telling them. BMW dealerships, in general, are not servicing these transmissions as they're out of the maintenance timeline that BMW is responsible for addressing during the warranty period. However, BMW does have technical information in their own TIS on how to refill and service the transmission in the case of component replacement, essentially discrediting the claim that the transmission cannot receive a drain and fill service.
How Do I Service BMW Automatic Transmissions?
The documents linked below are the technical information that every dealer has access to and references during a repair. The reason I have provided you this information is to clear up any confusion or concern as to why we offer the kits in question, to begin with. Unlike vehicle manufacturers, our goal is to provide as much useful and factual information to our customers and readers as possible so they can make an informed decision about the repairs they are looking to carry out. In that way, we do not operate like a normal parts retailer as our goal is to make European car ownership a more enjoyable experience.
How to drain and remove the oil pan
How to replace the transmission oil filter
How to properly refill transmission:
How to change the BMW/ZF 8HP automatic transmission fluid
How do I know if there's something wrong with my BMW's automatic transmission?
Transmission fluid that is burned or is heavily contaminated with wear material is a sign that there's something internally wrong with the transmission. In these cases, the fluid should not be drained, and the transmission should not be serviced. However, normally oxidized fluid without material suspended in it means that the transmission can be safely serviced with a standard drain and fill procedure as highlighted by the technical information linked above. It's pretty easy to get a test sample of the transmission fluid through the fill plug to verify its condition, and this should always be done before draining any transmission as a quick spot check. Additionally, there are many examples of incorrect services being performed by unqualified personnel and incorrect fluids being put into transmissions that have caused problems after the fact. Unfortunately, this is more of a common issue than it should be. These types of issues have created the negative hype around BMW automatic transmission services.
That should cover everything you need to know about BMW's "lifetime fill" on their automatic transmissions. If you're unsure if your automatic transmission has been serviced, or if you're over 100,000 miles, using one of our kits and following the guides above is cheap insurance to help prolong the life of your transmission.
If you want more BMW guides, DIYs, or amazing feature builds, you can visit bmw.fcpeuro.com or subscribe to our YouTube channel.
Gareth is the BMW Catalog Manager for FCP Euro and has been with the company since 2012. Gareth's BMW obsession started with a hand me down E39 528i when he was 17. From this car he learned how to do his own repair work while also learning more about BMW. When Gareth was at CCSU studying Marketing he had the opportunity to go to SEMA with the college car club. This is where he developed his love of the automotive industry. Since joining FCP in 2012 Gareth has sought out to develop one of the broadest and most accurate BMW replacement parts catalog. he can be reached at firstname.lastname@example.org