[ejonesie22]

New transmission fluid has fresh detergents in it and will cause the sludge to break loose, often time clogging the valve body and other passages killing the transmission. It also will cause it to leak since often the sludge in a worn transmission is doing more sealing than the seals and gaskets.

[exit82]

That explanation makes sense. Thanks.

Just adding new if it is low is all you need, I would guess.

I have a Plymouth Voyager, nine years old, with 126,000 miles. Tranny fluid and filter was last changed at 90,000 miles.

Any suggestions about changing the trans filter? I’m thinking that a new filter will be needed one of these days. Just change the filter and reuse the old fluid to avoid the new stuff?