My car is a 05 g35 sedan. I've done the drain and refill before but I forget do you turn the car on while you are refilling it? I've watched the videos on here and it looks like you leave the car off which is what I did before If I recall correctly. I just wanted to get a better understanding of what is going on inside the transmission. I know the fluid is in multiple areas of the transmission and a pump circulates it all. But when you remove the drain bolt only ~4qts comes out but then there is apparently room for 4qts up top when I refill before turning the car on and circulating the fluid.

 

There is a cold fill and warm fill line for the transmission oil dipstick.

If that's helps.

The FSM is available for download if you search ... for research purposes.

 

Essentially you're just draining "the reservoir" which is the volume held in the transmission pan, the other 10 or so quarts are still inside the valve body/torque converter. Drain and fill with the engine OFF, replace the volume that was drained out. I also STRONGLY recommend going for a 15 minute drive to get the fluid up to temp then checking the level when you get home.

You make the fluid level check with the tranny hot and the engine RUNNING for the most accurate reading, drive, park vehicle, run through each gear manually, place vehicle in PARK, check fluid with engine running.

 

oh that makes alot of sense now. sometimes the simplest answer is the correct one.

 

First gen AT's hold just under 11 qts. Per the 05 sedan FSM: "ATF: Genuine Nissan Matic J ATF Fluid capacity: 10.3 (10-7/8 US qt, 9-1/8 lmp qt)" I'm pretty sure it's the same for the coupe's transmissions as they both use the same tranny.

So a proper drain and fill will replace just over a third of the total fluid. I took an old 1 gallon plastic jug, like a milk jug, marked it off in quart measurements and replaced exactly how much drained out. It was usually around 3.75 qts. With a proper manual fluid pump it's a damn easy DIY as is the diff. I did this for over 100K miles and my method always worked perfectly.

 

I've got about 170K on my G and have done a few drain/refills over the years. I'll be getting ready to replace the ATF filter as well in my next service; I usually do it when the car is cold and then measure it. The fluid will expand if you do it when it's hot and might throw your measurement off a little.

There is a process where YOU CAN do it with the car running. But, that's using the transmission itself to do a flush. You unplug the return line from the radiator and keep pouring new fluid in until it runs bright red out of the return line. I wouldn't do that for fear of messing up and I do a lot of my work alone. I have to fill my Audi with the car running and only at a specific temperature and that was a PITA doing myself once as well.

 

There isn't really any need to replace the filter in those Jatco transmissions, it's not really a FILTER so much as it is a large particle screen to keep chunks of debris from getting into the valve body, it doesn't catch all the worn clutch dust that's trapped in the fluid, hence the reason to religiously stick to the transmission fluid change interval.

It wouldn't HURT to change it either though and you can also inspect for any other potential issues while you're in there.

 

Yep! Learned that one when I did my first transmission oil swap. Went to buy a filter and couldn't find one to purchase!