on my Tacoma 4 speed auto transmission(non -sealed) I just bought a case of genuine Toyota T-IV ATF off EBAY seller and did 4 pan drains and refills, much cleaner and easier than puling off a cooler line and ended up with the same results. I just drained every morning COLD and measured and replaced thru the dip stick hole the same amount for 4 consecutive days each day I drove the truck to get it to operating temp. and torque convertor lockup then repeated the COLD drain and refills, was a breeze without major incidents.