Not trying to get into a pissing contest, just telling you all that the fill for life transmissions are a typical 80,000 trans. It's not the fluid that makes them go out. After you do some homework on them, you will find that they are computer controlled, and they are always adjusting the modulating pressure to give the best quality shift. What does that do... for starters, when you start to have a transmission go out on a conventional trans, you start to get symptoms. Bad quality shifting, slipping, you know, something that you can kinda point at and say..... Hhhmmm, this need to go see a mechanic. But the Computer controlled transmissions fill for life, they dont do that. You do not get a symptom until its too late. MB has had many revisions for transmission modules. The 97 had 5 possible #'s currently. Some you can reprogram, others you have to flat out buy. Oh yeah, and by the way, the early fill for life transmissions, 2000 and under, have faulty thrust bearings and races. So before you come back and tell the guy I am full of it, do some research first, then get back to me.
Oh yeah, usually people who are changing the fluid, they are already getting a symptom, and rather then spending a bunch of money on fluid that's not going to fix it, I tell all my customers the truth, wait till you have to put one in, then change the fluid every 30,000.