yup a lot of people say changing old tranny fluid is pretty much a trannykiller ive heard its because the seals swell with the sudden changes in fluid composition but honestly im not sure thats factual lotta possibilities here primary amongst them is that people try tranny fluid changes to fix a dying transmission thus there is no causeeffect correlation just a very probable coincidence im also unclear on whether theyre saying it wouldnt have been serious if youre changed it regularly but you didnt and now that its old you cant change it without killing it or simply once the trannys old you cant change the fluid regardless of whether its been changed before