I under stand that all of the old tranny oil is not removed when changing oil is that right and if not how much is still left in the tourqe converter(pardon the spelling)there is not a drain plug on this model thanks ever one. 1996 toy corolla
On my Subarus, approximately 40-45 percent old fluid can remain when the contents of the transmission pan is emptied. I supect your Corolla is about the same. To do a full exchange, a fluid exchange (not a back flush) machine is generally used. When done properly you get nearly all the ATF exchanged out. Before this is done, a pan drop to replace the trans filter and to examine the contents of the transmission fluid pan should be done, and then the ATF fluid exchange done.
People all have their own solutions for things like this. In my case, I pull the plug whenever I have the ambition and am back in the States, this is 3 quarts which comes out, then add back three quarts. I use synthetic fluid of the correct type for my car.
If you do this, then soon do it again, you get more and more good fluid in there. If you do this from a new car, the fluid never gets in bad shape, and if you do it yourself it doesn’t cost that much.
The logic changes if the car is old and the fluid is in bad shape, and thus perhaps the transmission as well.
I don’t know about the Corolla. I am told my Sienna does not have a transmission filter, only a screen.
If you change the fluid every 30k miles the old fluid is in not such bad shape, and there’s no need to flush it all out.
Roy is right, even if he does like KU.