Quote: Read the Allpar link. It says that newer ATF does not play well with old style trans seals and will cause leaks.
In most cases when you hear tales of one particular type of fluid causing seal deterioration/leaks it's because the type of fluid was changed in an aged unit. If that particular fluid was used with the same seal material in a fresh unit there would be no leakage problems. Check the part numbers of the seals and see how many have gone unchanged.
Part numbers may not have changed in the last 40 years, but the materials they are made of Have changed in many cases as technology moves on. Like you say, I'd bet that most leaks using ATF+4 in older trans is a result of old seals that have spent years submersed in Dexron... but that is exactly the situation many of us are in. Change a converter or valve body in an other wise good transmission and think "hey, I'll upgrade to +4 while I'm in here. And then the leaks begin, bad idea.
Like you say, I'd bet that most leaks using ATF+4 in older trans is a result of old seals that have spent years submersed in Dexron... but that is exactly the situation many of us are in. Change a converter or valve body in an other wise good transmission and think "hey, I'll upgrade to +4 while I'm in here. And then the leaks begin, bad idea.
