Originally Posted by V8Nissan

So without plagiarizing the maintenance manual here is a basic rundown of how to service

Engine off, Drain fluid from pan using rearmost plug on the pan and then replace the plug.

Remove the plug towards the front of the pan and pump fluid into the pan keeping in mind there is a standpipe that is about an inch tall.

Once fluid overflows from the pan or after adding about 3 1/8 quart, reinstall the overfill plug. Run the engine until trans reaches 104 degrees fluid temperature. Also shift into drive and reverse with foot on brake to circulate fluid.

Here you can either drain and service again to flush the fluid or do the final servicing.

For final service ensure you have filled 3 1/8 quart of fluid or until fluid spills from overfill port. With engine RUNNING and fluid temp at 104 degrees remove the overfill plug. When fluid stops dripping it is at the correct level in park. Basically just like servicing any automatic in park, engine running , the difference being you are draining off excess fluid while running instead of using a dipstick.

Also be sure to only use Nissan Matic S fluid. Nothing else

Make sure whatever method you choose to fill the transmission through the overfill port actually works before draining your fluid. Otherwise you will be stuck lol. I have not tried a small piece of hose. My other idea was to purchase a spare overfill plug from Nissan or a bolt with correct thread and crush washer and drill out the middle and then weld some type of fitting to it that you could hook a hose on to. This procedure is probably not a great place to start for the novice mechanic but for a decent mechanic with some ingenuity it can be done fairly easily