[AX3]

BMW does not recommend changing the tranny fluid on my 2014 X3. I have 68K miles on it and if it was any other vehicle I would change it. What I would like to know is if used fluid with 50 or 60 or 70 or 80K ect. miles has been analyzed by a lab to determine if it is advisable to change it at that mileage. Who do you trust? If it wasn't so difficult to change I would just do it.

[Wgosma]

There are numerous postings/threads on this subject on several BMW forums, such as these two https://f30.bimmerpost.com/forums/sh....php?t=1637336 and https://f30.bimmerpost.com/forums/sh....php?t=1644401

From what I've read, ZF, the manufacturer of the transmission, recommends a fluid change (drain/fill...not complete system flush) at about 60K or so miles.

This is really pretty simple to sort out: every lubricating fluid - be it in a car's automatic transmission, engine motor oil, differential gear lube, etc.; i.e. fluid used to lubricate any moving/rotating component will degrade over time and use- some fluids will degrade faster than others, such as motor oil as it's subject to relatively high heat (compared say to transmission or differential lubricants), so it makes sense to change the fluid periodically.

BWW and many other car manufacturers have for some time now touted 'lifetime' fluids- in the transmission, differentials and even the fluid in the coolant system. But ask BMW what is a 'lifetime'....ask three dealers/service advisors, technicians, etc. and you'll likely get 3 different answers. This 'lifetime' fluids is a marketing tool.

I've seen one posting of an transmission fluid analysis done by Blackstone labs- ZF 8 speed tranny fluid at about 65K or so miles; the report showed the fluid within spec, only a very slight out-of-spec measurement of viscosity. Did that owner need to change his fluid right then?....probably not, but in my mind that's smart preventative maintenance.

Bit of common sense goes a long way: Transmissions have gotten better over time, lubricating fluids have improved greatly....still, NOTHING lasts forever when it comes to rotating mechanical parts and their lubricating fluids. If you're going to keep your car for say 100K miles, you can probably very safely get away with not changing some fluids; if you're planning to keep the car for the longer term you're smart to do periodic fluids changes - all fluids - preventative maintenance pays big dividends on any car, particularly on BMW's.
Gook luck/Bill