Originally Posted by
Fast Freddie
If you changed your own transmission fluid, by simply draining and re-filling, you haven't really changed it at all, since only a limited amount of fluid rests in the sump. A great deal more still lives in the torque converter.
The performance of the T/C relies on properly functioning fluid.
If you ask your transmission shop to do a full 'flush' of the system, as part of a transmission service, you will know for sure if its in need of a rebuild or not, for a (relatively) small amount of money
FWIW, the performance of my transmission improved considerably when I did this and it cost me $360.
Good luck.