[thegazelle85]

Hi there:

I recently picked up a 2011 535i Xdrive - high kilometers (245,000 when I got it). Since the day I test drove it I noticed that when you are lead-footing it and flooring it, the gear changes are not smooth whatsoever. at about 2000RPM it is jerky and I feel like the car is zapped in power. This is probably around 10-60KM/hour maybe? After that it is smooth. Now, I have a 2011 328i Xdrive as well and that thing I can floor it and it just goes - very smooth gear changes and no jerkiness.

A lot of what I read indicates that many dealers are telling owners that is the way it is. I did some reading online and heard about the adaptive transmission throttle reset (or something like that) procedure. I did it, confirmed that it was done (by the clicking noise from the engine after) but there wasn't any change when driving.

I could of course, just go easy on the gas and drive it like I am Andy Griffith in a Buick, but only because my 328 is not like that (and I have an Acura SUV too that, while not really have much guts, shift smoothly when I floor it). Reason why I mention flooring it is that it is handy when entering the highway that I can accelerate quickly to merge.

This brings up whether I should consider a transmission fluid change? Would that help. It seems like some people are saying the transmission fluid should be lifetime. But due to the high kilometers, I am wondering if you all can provide some feedback. I know the differential fluid was added recently (before I bought it, it was at the dealer and apparently it was returned without differential fluid, which my mechanic remedied). Anything else I can try, check, etc. I heard there is also some software updates to the car computer that can be done, but I just want to get some insights whether that avenue is worth exploring, or is there anything else I can try. I am not handy and not very knowledgeable on cars.

Thanks in advance.

[Surly73]

Whenever I've purchased a used car I change every fluid in it just so I know what's going on. (Even power steering).

The catch for you is that you're already at 2.5x the recommended manufacturer (ZF, not BMW) interval for fluid and filter change. I would still seriously think about doing it. There could be a leak and the level isn't right. The filter could be clogged up with wear material and there isn't enough flow etc...

There's misinformation out there that changing fluid on an old transmission is a death warrant. If replacing 1/3 of the fluid with clean fluid breaks a transmission, it was on its last legs anyways. But, it could happen. YMMV, there could be negative outcomes, you do you etc...

If you proceed - nothing but OEM. Kits from FCP, ECS include genuine ZF Lifeguard 8 fluid and a genuine ZF pan with integrated filter plus all the bolts and other hardware you'll need. Drain and replace, set the fluid level by the book, use ISTA or similar scanner to read temperature. Do not attempt any "flush".

It's possible you have a solenoid or mechatronics issue. Scanning for codes using ISTA or another BMW-specific tool may help.

DO NOT reset transmission adaptations even if someone from a forum tells you to, especially at that mileage. The "throttle adaptation" you reset is fine.

xHP article on the details of "transmission adaptations":
https://www.facebook.com/xhpflashtoo...3761651273188/