Found this on Dodge Charger board- it mentions about changing every '8 years' - 80,000 KM under heavy use - but fluid is described as 'life-time':
Updated 8/30/15
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Set aside the discussion of what "lifetime" means.
This post is to clarify what ZF actually recommends.
I have seen some misinformation regarding what ZF claims about our ZF 6HP transmissions. Specifically I have seen people claim that ZF does not agree with BMW's lifetime fluid claim and that ZF claims the fluid should be changed at 50k miles. That simply isn't what ZF recommends for normal operation:
Here is fluid change on Dodge Ram Eco Diesel:
"A lot of discussion has occurred on the topic of oil change intervals for ZF transmissions. It is important to adhere to your vehicle manufacturer specified change interval and it is very important to use authorized fluids. ZF Lifeguard fluids are designed and tested to retain characteristics through normal lifetime operating conditions; per the OE vehicle manufacturer specifications."
It is true that ZF also says:
"In instances of extreme driving conditions, special environmental considerations, and driving factors which place an increased load on the transmission, it is advisable to perform a drain and fill between 50k and 75 miles, or 8 years."
