Auto Trans fluid drain and fill improves shifting

[bmwfortwo]

I just did a drain and fill on my 2008 328i CPO sedan at 41k miles and noticed an immediate improvement in the smoothness, speed and quality of the shifts. Particularly in sport mode the trans would hang up around 4k rpm during normal acceleration before the change, now it rolls up and smoothly shifts without delay resulting in a more direct and continuous acceleration under medium throttle.

I bought this car earlier this year with 34k miles and dont know much about its history other than the VIN service history which doesnt say much. I paid $286 at a dealer for this, well worth it for the peace of mind in addition to the improvements in how it drives. BTW I was quoted about $1,100 for the filter/pan replacement which I suppose will be needed by 100k or so, if I keep the car. For the record I am also doing interim oil changes which one dealer refused to perform, happily done by my favorite independent shop using BMW oil for $130.

[e66man]

Good to know. What fluid did you use? Where did you buy the pan/filter?

Hmm....now I don't remember if your trans has the filter/pan all in one unit like the 335.

[bmwfortwo]

I just did a drain and fill, didnt take off or replace the pan and filter. My purpose was to renew what fluid I could at a reasonable price. I understand that the filter/pan combo is somewhere around $800 and although a superior approach I choose to save it for the 80-100k mile change, if I still own this car. As far as I know, this year 328i uses a GM made trans and I believe the 335's use a stouter ZF. I'm sure someone will chime in if I'm incorrect.

I had this done at a BMW dealer, who used or at least i paid for 6 quarts of Dexron ATF at $19.40/qt and $155 labor, mostly because it is under CPO warranty until Jan 2015 and I feel better having a CCA friendly dealer doing and documenting the work. Like many things on this car, I could have done this myself with a lift.

Thanks for your note.

[S197GT]

Just took our 06 330i in for an oil change (105k miles) and got a 328xi loaner w/8k miles on it.

I couldn't feel a difference in the shift quality.

I asked our SA if BMW was sticking by the lifetime fluid claim of the transmission. He said yes. After a test drive of a nearly new 3-series I continue to believe BMW.

Other observations:

The 328xi felt slower, softer, and had less grip (we have Conti DWS vs. stock Conti whatevers) but had better NVH dampening and all the switch-gear action was crisper... oh, better side mirrors...

Didn't feel like I was missing out on anything... except a car payment!