Question on BMW 3-Series E36 Tranny_Fluid_Auto

My '98 e36 328i has 305,000 kms on it and its starting to produce a low frequency drone when accelerating, especially from around 80km/h. I thought it may be the diff, so I replaced the oil with no improvement, but now I am leaning towards the automatic transmission. As BMW recommends that the transmission fluid never be changed, I have never changed it. I also understand that by replacing it, I may remove friction material that is possibly keeping it working, and that the adaptions could possibly not be working 100% at this high mileage. Could it be that over the years that a significant amount of fluid has escaped causing the drone, and that the level is low, in which case, I could simply safely top it up a bit?

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[Nick at Pelican Parts]

If you have a mechanical noise, I would think the old trans fluid would not be the cause. You are going to have to isolate the area of the noise, then inspect the rotating parts or bearings in that area.

- Nick