hey Scotty, i have 100k miles on my 'new' used bmw 1 series. it has a zf6hp19 trans, and that has a "lifetime" filling. of course the service schedule doesn't mention anything, so i better replace the stuff asap, right?
cheers from the alps

Yes, I would. but realize that fluid costs a ton and I can't even buy it, BMW won't sell it to me, they get it in giant barrels you can't buy

thanks for reply, i found a service kit for $250-ish, which is about a third of what zf charges.
it includes the oil pan with filter, screws, the seal, and 6 liters of original oil. as i found out, zf recommends a service every 80-120 thousand km. considering the trans is built for twice the torque my engine delivers, i guess i still have some margin, but i gotta get it done for sure and the guys that service my cars don't want to do it -.-

so we were at the diy garage today, had the whole thing done following the official instructions in a bit over 2h. the old fluid did not contain any chunks, wasn't even too black and did not smell burnt. the friend that helped me is a mechanic, but he never did this on a beemer before. that being said, it really is dead easy to do. cost me less than half of what i'd have paid for having it done by zf.
i did end up buying the kit from a different seller, the difference being no new screws but one extra liter of oil which we ended up not using. lol.

oh and it still runs as smooth as before. if not better.