Transmission fluid drain or not? Dealer say its lifetime

[RRPhil]

Just to add ZF’s view on the subject…….

In July this year, as well as a regular re-issue of their TE-ML11 lubrication list which stated (as usual) :

5-, 6- and 8-speed as well as 4HP20 automatic transmissions:

ZF 5-, 6- and 8-speed as well as the ZF 4HP20 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.
In each case, only released ATF oil may be used for oil changes. And oil changes must be performed in accordance with the relevant specifications.

ZF also introduced their new ‘oil change kits’ to the market :

http://www.zf.com/corporate/en/products/services/report/03_2013/oelwechselkits/oelwechselkits.html



So clearly ZF support, to some extent, fluid ‘purification’ changes for their transmissions (which replaces just over half of the fluid – the kits contain 7 litres) and advise that a fluid change may be necessary at between 50,000 and 75,000 miles (or 8 years) depending on the type of use.

For ‘normal operating conditions’ the official 5HP24 repair manual states :

“The transmission is filled with life-time oil. The oil does not have to be changed until it has been in use for ten years.”

and similarly in the 6HP26 repair manual :

“The transmission is filled for life with oil. An oil change is not necessary before 160 000 km or 10 years.”

Anyway, that’s the transmission manufacturer’s view.

Phil