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Old 09-06-2010, 08:57 AM
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madurodave madurodave is offline
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Location: NH
Join Date: Oct 2008
Posts: 5,669
Mein Auto: 2007 Z4+X3, 2006 530Xi
Originally Posted by bimmernut1 View Post
First, I don't think you'll see any performance improvements from changing transmission fluid. It's common knowledge, BMW says their fluid is lifetime. Perhaps that's legitimate, perhaps is related to the fact that they have a maintenance free program for the first 50k miles and with fluid at $25 per liter, the cost would add up pretty fast.

I think the consensus is that you can't harm the car by changing the fluid. I would definitely change it at 75-100k miles but it's not something you have to do with the frequency of an oil change.

I just changed the fluid in my M5 this spring and will probably change the fluid in my X3 next year.

The next big discussion topic is always what to use for fluid. Many like Redline, Mobil1, and Royal Purple. Rather than losing any sleep over it, I chose to go back with the OEM fluid. I probably wouldn't go to the effort of trying to change the filter unless I were going into the tranny for maintenance reasons.
I think if you go to the effort of changing the fluid, you should also drop the pan and change the filter. If nothing else, you can clean the magnets in the pan, replace the filter and do a quick visual on the internals.

I also read a lot about frequency. I almost have 71k on my X3 now. I will try and change it this fall but worse case in the spring. I just did a quick look-over on the X3 in preparation for the Inspection II and the entire vehicle looks very tight as far as leaks and all the rubber boots and the drive belt look in excellent shape. Rotated my tires also and checked the brakes. They will probably go to 100k miles (they were changed under warranty which helped a lot)!

My garage: 2013 BMW 550xi GT, 2007 BMW Z4 3.0si Manual, 2006 BMW 530xi

Retired: 2007 BMW X3, 1998 BMW Z3

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