[abcommercial]

2006 325i with 111k miles (EDIT: automatic). I want to get this car to at least the 200k mark and so I'm maintaining it with that goal in mind.

I had my BMW dealer do the service, which entailed changing the filter assembly, draining (they say) about 5 quarts of oil (whatever the pan holds) and filling back up with new fluid. No flush, they said, because the thin new fluid sometimes causes problems....or stated differently, perhaps removal of ALL the old fluid could cause a problem since that old fluid contains desirable frictional material that you don't want to completely get rid of.

What should I expect or notice? Car drove/shifted fine before, and drives/shifts fine now. I don't notice any improvement or difference. Should this service prolong the expected life of the transmission? Is it nice to have at least some new fluid in there? Does having the new filter help?

[trufus]

Is this an AT or MT?

[ti8589]

MT does not have filter

[trufus]

Originally Posted by ti8589

MT does not have filter

Good to know.

I've heard that transmission fluid changes on BMW ATs is a bit of a crapshoot. It might help the tranny on to 200k or it might loosen up some deposit that was holding the whole thing together. Time will tell.

[MrCairo]

Originally Posted by abcommercial

2006 325i with 111k miles. I want to get this car to at least the 200k mark and so I'm maintaining it with that goal in mind.

I had my BMW dealer do the service, which entailed changing the filter assembly, draining (they say) about 5 quarts of oil (whatever the pan holds) and filling back up with new fluid. No flush, they said, because the thin new fluid sometimes causes problems....or stated differently, perhaps removal of ALL the old fluid could cause a problem since that old fluid contains desirable frictional material that you don't want to completely get rid of.

What should I expect or notice? Car drove/shifted fine before, and drives/shifts fine now. I don't notice any improvement or difference. Should this service prolong the expected life of the transmission? Is it nice to have at least some new fluid in there? Does having the new filter help?

Definitely changing the fluid and filter at regular intervals will not hurt your transmission. Now there is some debate on whether or not the BMW recommendation of 100,000 miles is too long of an interval or not. They're not necessarily interested in your car going for 200,000 miles so I would just have someone check your tranny fluid every 30,000 - 50,000 ( unless you're a DIY person ).

[abcommercial]

Is having some new fluid and some old fluid mixed together in there preferable to either having all-new fluid or all-old fluid?

The tech says BMW recommends (whether officially or unofficially to dealer, I don't know) that the dealer do the drain and fill with this service rather than the full flush.

[El Cheapo Loco]

Originally Posted by abcommercial

Is having some new fluid and some old fluid mixed together in there preferable to either having all-new fluid or all-old fluid?

The tech says BMW recommends (whether officially or unofficially to dealer, I don't know) that the dealer do the drain and fill with this service rather than the full flush.

This is true for all AT, not just BMW. Full flush MAY cause issues, especially on higher mileage AT without previous maintenance.

[mike3000fl]

Would have been nice to have taken some of the old ATF and send it off for analysis.

Would be interesting to see what properties it had remaining at 100,000

[Wires]

Honestly, you shouldn't notice anything. What you should expect is longer life since the fluid isn't worn out and full of crud.

If you noticed a big change, then that usually means the cruddy old oil was holding it together. That usually follows with it flying apart!

[DUI Elite]

I did my first fluid replacement at 49k miles so now I'm looking at doing it about every 50k miles.

You really shouldn't notice any difference. If you drive aggressively, you might notice a difference when your line pressure goes up (also something that happens when you put it in sport mode).

But otherwise, buttery smooth is all you're looking for.

[gatoman39]

No difference is a good sign. You don't want to address this when there's a problem, that's when it gets expensive. ATF is one of the most neglected services, and it's really sort of silly how easily preventible problems with a slushbox can be avoided by doing this simple maintence.