how much tranny fluid?

[SilviaSR20DET]

Im about to change my tranny fluid very soon and im just wondering how much fluid is needed to fill. Im leaning towards the valvoline gear oil over the mobil 1 because of the price differences. Are they the same or is mobil 1 better? Im having trouble finding the tranny fluid plug, can someone give me an idea of where it is or have any pics. Thanks

[thelinja]

My tranny took about 2.5 qts of Redline (at least that's when it started dripping out of the fill plug.) The drain plug is located on the very bottom of the trans. and the fill plug is located on the driver's side of the tranny next to the cat.