This is for a Honda automatic transmissions - specifically year models '99 and '01, if that matters. You know how its always a partial drain on Honda auto transmissions. Almost half of the old fluid still stays in there. Now with the drain plug open, if fresh atf is poured into the filler hole or dipstick tube, will it push out the old fluid ? Or its just the fresh fluid coming out ? I relize this would have no effect on the old fluid in the cooler lines but still would it be worth running a couple of quarts through like this to get as much old fluid out ? or not ?