When I change my trans oil, I take the rubber line off going into the oil cooler, & aim it into a 5 gal plastic bucket. I have someone start the engine, place shifter in "N", and let it pump the fluid into the bucket. When it quits flowing, have them shut off the engine. Most of the fluid is slung out of the converter this way. Then, I drop the pan, & let it drip drain all night, replace the filter, & refill.