It uses atf. You could use something like Royal Purple syncromax synthetic fluid too. I've found the easiest way to fill it is to get under the car, remove the plug, remove the shifter boot/bezel, remove the rubber dust boot and run a short hose down through the center console right off the oil bottle. Otherwise, you'll need an oil squirt can because it's tight under the car for pouring access. It will hold a squirt more than 2 qts.