I agree I don't see the need for tranny additives. Its ust that I don't want to break my line connection at the radiator and would like to cut the rubber line at at a reasonably lower point and add a steel line "go between" say 3/8 and clamp it down. So whenever I conduct a flush,all I have to do is just disconnect via the "go between section" without disturbing the questionable rusty connection. All of my other 740's have passed the 450-500,000 mile marker (original mileage). I have faith in my 850. I just think that Volvo shouldn't encourage such a long extension of time for a maintenace interval that could save people from monetary migranies to say the least.