I have 103,000 miles on my 06 AT TL. About 7,000 miles ago I drained and filled (3x3) the tranny fluid for the first time since the dealer put a new transmission in at 36,000 miles. Over the past couple weeks I've noticed a significant rumbling and vibration after when in reverse. This occurs at any time in the reverse gear and doesn't seem to get worse or better when backing up or idling (but its hard to tell as I'm not backing up at a high RPM). I have not noticed this problem after driving it for a while. I checked the fluid level at it looked fine but the was while cold. There was a tremendous amount of grey soot in the old fluid but I guess that's to be expected with the gear dragging design flaw right? I'm looking for suggestions to further isolate the problem or a guess of the problem with expected consequences and possible fixes. Thank you everybody. Since joining Acurazine I have already fixed my power steering whine, Bluetooth, a headlight and more just from the knowledge shared here. I hope I can save this transmission,

 

Something similar is happening to my TL as well.. does anybody know what's going on?