As the title states, I consulted the dealer and my Indy BMW/Mini mechanics and BOTH said, absolutely do not flush the trans fluid unless you want to suddenly have issues. Both actually said they'd refuse to do the work as well. Huh??
I thought it was pretty prudent to flush a trans at about 100k?
Indy said that either change the fluid every 30k or never.

Im not understanding this. Can anyone with an actual tech background shed light on this?

 

Manual transmission? I have heard this with automatics, but automatics are witchcraft anyway. I cannot think of any good reason why they would say this about a manual transmission.

 

Yeah, manual transmission. Strange responses. I bought the Trans fluid, not sure if I should return it or proceed. Is it true that if you do the first flush at 100k you're asking for issues? If so, why?

 

This makes no sense. BMW says this is lifetime fluid. Manual fluid does not get “dirty”. You will be replacing the additive package and cleaning out any actual metal. From my experience much smoother shifting after doing this.

 

Not clear here you are using the terms "flush" and "change" interchangeably, if you are, please don't. Flush generally means filling the trans with a solvent to remove deposits, followed by a drain after a very short period of operation.

All gear fluids wear out over time. Lifetime fluids are largely a marketing gimmick. Best guess is that lifetime fluids have been optimized for long change intervals, that does not mean the additive package will last forever.

Regarding the "rules" for fluid changes from the dealer and the Indy, I lean strongly toward "baloney" as the appropriate assessment. These rules are ancient urban legend going back decades and may have had some basis with crappy oils of 80 years ago.

Change the fluid for new, with the following caveats:
1) Do not use any type of flush, odds are high you'll end up with snake oil. Unless you can find a lubrication engineer that can make a recommendation for such, avoid flushes. I've never used a flush, ever, with any manual trans in any machine or auto. If you have verified a need to remove deposits, then accelerate your change interval (5/10K miles) instead of 30/50K)
2) Be certain you have the correct spec for the replacement fluid

 

I would add to that that "flush" in my own experience with it -- which was a long time ago, granted, and a process my then-service department stopped using entirely -- is a powered operation involving pumping old fluid out and new fluid in. Don't know whether that is still the case but I presume so when "flush" is the term I hear used in connection with a transmission (or coolant system) and the term is used as a verb rather than a noun.

I see a lot of back-forth going on in not-this-forum about whether both the manual and AT on the MINI (all 3 "new" generations) and the terminology swapping -- and breakdown of clarity about what is and is not being recommended for or against -- is really, really, REALLY bad out there. Thank you for making this point. I'm about ready to start screaming it at people in the other forums I participate in

 

Hi, thanks for the info!
A service tech told me once that any kind of "flush" involves draining, then leaving the drain open and adding new fluid until it comes out "clear and clean" on the other end. Only then do you tighten the drain bolt and begin filling with fresh fluid.
A fluid "change" was just draining, closing drain plug, filling with new fluid and so he advised you always end up with a bit more contamination than a true flush.
In terms of doing a dedicated cleaning cycle with some types of solvents etc, Ive never done that for any fluid changes/flushes. And truth be told, the only one that I proper "flush" entirely until I see clean fluid coming out is the brake fluid. All the others are "changes" with a simple drain-and-fill process.

Oh, and an update! I proceeded to do change the MTF for the 96k mile MCS Manual using Valvoline. The old fluid was nearly black and full of black "dust" in suspension within it too.

 

It’s been a couple of months now, have you had any issues? Does everyone think a fluid change would be a bad idea on a ‘15 F55S AT with about 100k miles on it?

 

Its been perfect. It smelled bad on occasion for a good month but i googled and this turned out to be normal. It eventually went away and the transmission shifts essentially the same. Not sure its necessary but assume so, as you eventually want to change all fluids as cars get old enough.