Changing trans oil on a G35 6MT:
NOTE:Do NOT use GL5 transmission fluid. It will damage the synchros in the Nissan transmission. You need GL4 fluid. Most fluid you buy at autoparts stores is GL5.
I recommend a mixture of 2 quarts Redline MTL (70W-80) and 2 quarts Redline MT-90 (75W-90), as Nissan calls for 75W-85 oil.
Jack up car and place on jackstands.
You will see 1 drain plug on the bottom of the transmission, and 1 fill plug on the passenger side. Both use a 10mm Hex Socket.
Slide the oil drain container directly under the drain plug and remove the drain plug. Wear gloves, as it pours out very fast.
Remove the fill plug and allow the contents to drain for awhile.
While waiting for the fluid to drain, prepare the new fluid for insertion. Get the fluid suction gun ready, and open all the fluid bottles.
Check that the fluid is fully drained. Replace the drain plug and torque it down.
Use a hand-held pump to pump new fluid from the bottles into the trans.These can be bought for around $10 at any autoparts store, and save a TON of hassle.
Once you have finished there may be some overflow dripping out of the fill hole.
Insert the fill plug and torque down per the manual.