Originally Posted by TwinTurboGTR

pre-facelifted E53 were equipped with 2 different tranny manufacturers. The 3.0i came with a 5 speed GM tranny while the 4.4/4.6's were equipped with a 5 speed from ZF. The entire model line up did not have a 5 speed from GM set up. Only on the 3.0.

But to answer the real question, There is no correlation between which tranny goes first or which one is more prone to failure.

The only thing I can think of is this. Now more and more manufactures are making it harder for the DIY'r to work on his/her machine. Some are going so far as to remove the Engine oil dipstick. Now they do this because there are some DIY'rs that go rogue and put in anything they want and are ignorant to what their rides need. Manufactures were probably sick and tired of doing warranty work because of rogue DIY'rs. So they eliminated the Dummy Stick and put in a sensor and MADE you take it into a dealer to have them do it.

Now from being around on this forum for years, I have never come across a post that was titled "Low trans fluid level" message. I have only seen "Trans fail safe". Most of the post I see regarding trans fluid is because a poster will come on and say, "Thrans is slipping, roaring, bucking..." By the time they crack the pan open, the trans is toast because the fluid level was too low. So what I am thinking is, the reason why the trannys may fail, in most case atleast is because maybe the gasket on the tranny pan has give way. It starts as a slow drip and one may not notice or may think, "Oil from the OSV." As time goes on the leak may get worse. As this time goes on the fluid level is getting lower and lower until "BANG" you get some slipping and it is too late.

This is just my opinion. Is this why most tranny's fail, I don't know. But if you take away too much fluid and the clutch packs have nothing to use, then yeah, my theory makes sense. But if the tranny was just neglected all the time, then that would fry a tranny too.