To my knowledge its not been changed in it's life gonna change it as soon as i can find the time i work 6 days a week and 10-12 hours a day. What's the best way to go about doing that on these drop the pan and drain it that way or pull the hoses apart and run it through the gears replacing it in small steps? And do I have to use nissan fluid or can I get different branded fluid such as royal purple etc?