HOw many miles

[hpy540]

Ok, picked up my x5 for a song. Cheap. It has 187k on it. I am longbtime BMW owner. 2 M5s 1850i. I set mom up with a nice 2002 540it. I ended up hooking a 130k mile extra transmission for mom from a friend of mine that was parting these out. I have heard with the lifetime fluid, the auto's will last about 230k if you are nice to them. Then usual only clean accumulator screen and new fluid and off and running again. How many miles out of a trans in an x5 4.4? I have heardlots of different things. This x5 didnt have a hitch on it
. But i would like to put one on as a backup. I have a Duramax for the heavy stuff.