This may sound like a dumb idea and it probably is , but if a person buys a brand new Ranger
then say when he has 30.000 miles on the Ranger he sucks out a quart of
trane fluid from dipstick every 6 or 8 months and replaces it with new fluid
in other words 1 quart out then 1 quart in ,the fluid itself will always be like
new true or false what is your opinion Thanks.

 

False
Do it right and drain the old fluid , along with the junk that collects in the bottom of the tranny and recirculates when driving , and refill with new fluid.
There gets to be a lot of particles suspended in the fluid . Why leave it in there ?
The filter can only remove so much and has to be changed anyway.

 

false, the fluid degrades over time. When changing ATF fluid be sure to wear safety glasses and rubber gloves. ATF fluid from any of the reading I have done on it is actually not healthy to be exposed to direcly. Just like being exposed to motor oil direclty (on skin, in cuts etc.) is not healthy.

You do not only want to change your fluid by dropping the pan, but instead you want to have the transmission flushed. The flushing gets more of the fluid out of the transmission. Be sure to have your transmission filter changed as well, there is all the contaminents in that along with any fine metal particles from the original brake in period of your transmission.

Change your fluid reguarly, and you will have a transmission that works properly for a long time!