I agree with SlickGT1, this myth is ridiculous. People often change their fluid in response to a problem, and then make erroneous claims that the fluid change caused the problem. I don't understand comments about "shocking" the tranny with fluid change. It's got a big filter folks, and 4 magnets in the pan as well. All these collect is clutch plate material. It's a sealed system not subject to combustion like the motor. The insides of a tranny are amazingly clean until something fails. There are not a lot of wear items; friction plates, steel plates, bearings and rubber o-rings are really about it. Spend a few days on the Bob is the Oil Guy website, or better yet, send your 100k tranny oil in for a UOA, see how well it has held up scientifically. The rest of the world changes oil regularly because IT is the main wear item. This lifetime fill stuff is just marketing, that was eventually re-thought.