Transmission fluid--change or not?

[csieminski]

Hello, I have a 1990 535i with 140,400 miles on it. Of course, it is an automatic transmission. I've had the car for a little over 10,000 miles (since April) and the transmission has shifted and continues to shift beautifully--extremely smooth upshifts, rapid downshifts, higher rpm upshifts in S3 mode, etc.

I have read about many transmission failures (including a 1995 525i on this board with only 92K), and have also heard that the ZF 4HP22 in my car is only expected to last to 150,000 miles. I also know that I never changed the fluid in the Acura Legend I had from the time I purchased it with 150,000 miles until past 200,000. It began slipping at about 180,000-185,000 miles, though the problem didn't really worsen for the rest of the time I had the car.

I came to the conclusion that frequent transmission fluid changes (every 10,000-20,000 miles) would be best for my 535i, and planned to do one soon. However, when I spoke to my mechanic about this, he said BMW only recommends fluid changes every 100,000 miles, and while doing one now wouldn't hurt anything, such frequent changes could actually harm the transmission.

This same mechanic sold me the 528e I had for two years/40,000 miles, and pointed out that, while the engine had been rebuilt just before I bought the car, the transmission was completely original. THE CAR HAD ALMOST 300,000 MILES ON IT WHEN I SOLD IT (and shifted perfectly), and he added that he has never seen a 4HP22 transmission fail with fluid changes every 100,000 miles.

Now I'm not sure what to do.

[Antiburn]

The fluid in the trannys is suppousted to be this super synthetic stuff that should last as long as you own your car. Unless you one of those people that own it for 25 years +. I never flushed a tranny yet but It would puzzle me how to fill it back up. I do remember someone talking saying that theres a plug at the top of the tranny but I never looked or found out if it was true. I do know that there is a plug on the bottom and if your not paying attention you could accicdently unsscrew that instead of your oil drain plug. If you wanted it flushed I would take it to a dealer and ask them to do it, if you even can even do that. Might cost you a little bit but it might be worth it if your cars shifting odd.

[jeffreyb4me]

hey there 'csieminski', how've you been?? a couple of thoughts [rambleings?] on your trans.fluid concerns.............Automatic trans. fluid changes have always been kind of a fickled thing. Waiting too long is never a good thing but changing fluid on a 'marginal' trans can lead to quick 'failure' which was coming anyway but the reduction of the 'added'
friction coefficient of the dirty fluid can lead to 'earlier' clutch pack slippage, which were worn anyway, still following me?.....regular recommended
maintenence is, obviously the best plan.........
a] your trans doesn't use synthectic oil ! !
b] regular maintainence in your car should have
included fluid changes every Insp.I OR Insp.II
service [not both]......
c] with the 4hp 'A' clutch problems of the late
'80's BMW changed the trans. 'service' schedule
from each Insp.II to each Insp.I service.
d] IF [and I 'think' you should] you choose to
service the transmission I'd recommend a 'Machine
Flush' which gives you a COMPLETE fluid change
unlike a drain and partial refill.
e] these transmissions CAN last a long time ! !
f] wish I had a DO, DON'T DO answer for you.
g] my BEST to you ! !............................jeffb.

[csieminski]

Thanks very much for the reply, jb. I was kind of hoping you would notice this thread (although I appreciate your response also, Antiburn).

As I said, my transmission shifts PERFECTLY, which makes me think it could not be screwed up by a fluid change now, although the stakes are raised should a castasrophe occur. You're right, I think I'll get a machine flush very soon. I bought the car from a dealer in NJ, and even though it was an original owner car, I have no records on it. I think the original VA owner traded it into Passport BMW in Marlow Heights, MD, from which it was shipped to the independent NJ dealer, where I then bought it and drove the car back to MD . I have all service books, window sticker, etc. but no records.

Regarding Inspection I and Inspection II service, could you elaborate more about these? I hear a lot about this, but the inspection lights on my 528e would go on and off at random and I never paid attention to them, plus the engine had just been rebuilt anyway before I bought the car. Will the message pop up in the LED display on my 535i? How frequently does this happen, etc.?

As an aside, I can't help mentioning this minor thing. The 535i is my third car, but the first with heated seats . Having just fixed my power headrests, I'm wondering if it would be possible for me to cheaply tackle the following problem: The passenger seat heat works fine, but only the lower cushion of the driver's seat is heated--the backrest does not warm up.

I at first figured I was out of luck as there was probably a cracked wire somewhere deep within the seat. However I'm wondering if there's anything I can check before I write this off--fuses, connectors, etc.

As always, thanks!

[jeffreyb4me]

hi csieminski...let's see.
[ ON YOUR 535i ]

Inspection I [every 15K ] = oil service, valve adjustment, cabin filter, complete visual inspection,
park shoe adjustment, DIS/MoDiC systems Fault Survey and printout, possible A/T service [see owner's manual or schedule ] [Insp. II ? ?]

Inspection II [ every 30K ] = Inspection I, + air and fuel filter change, sparkplugs, inspect cap & rotor, brake flluid & coolant change.

I think that covers both.

On your seat heaters, checking first is always done but the most [by far] common problem is the
heating pad elements themselves with requires dissassembly of the seats and upolstery to replace them [there's no 'repair']

Best to you again.......................................jeff.

[csieminski]

OK, thanks very much!