Back flushing a transmission is BS, it cannot be done. Some idiots who try to appease peoples concern that the filter cannot be replaced in a flush with tell spout this BS.
As Todd Z, said, just get a simple flush and you should have no problems. If you flush your transmission regularly, your tranny filter will easily last 100K miles. Remember that a transmission filter is NOT designed to act like and engine oil filter. A tranny filter is not designed to trap and collect dirt or contaminates. It is only designed to stop them from getting sucked up from the pan and circulated through the transmission.
Most of the debris in the fluid is small metal particles that wear off from the friction clutches and bands in the transmission. Transmissions have a magnet in the pan to trap and hold these particles. The filter is there to prevent any particles still in suspension in the fluid from getting sucked back through the transmission.
Once the engine is shut off, these particles that were stopped by the filter fall harmlessly to the bottom of the pan where they are trapped by the magnet and prevented from getting sucked back through the tranny.
The tranny filter is not like an engine oil filter that traps and holds all the dirt and will eventually become clogged. The engine oil filter traps all kinds of contaminates and byproducts from combustion and must be replaced periodically. Transmission do not hold onto the particles they trap and while a very small amount of particles may become trapped or lodged in the transmission filter, it cannot become clogged as to prevent fluid circulation unless the fluid was never changed or flushed. If transmission fluid is not changed it will eventuall become sticky like a varnish and that coating on the filter and other parts will lead to transmission failure
I always recommend that if you do regular tranny flushes every 25K-30K miles or more if you tow, you can easily go 100K+ miles before you will need to change the tranny filter.
...Rich
