Gearbox Oil
Gearbox has two plugs (I think they are 19mm hex) one on the underside facing towards the floor and one on the side of the gearbox casing above the passenger side driveshaft. The lower one is the drain and the upper one is to fill. You undo the lower one from under the car and drain out the old oil. Leave it drip for a couple of hours if possible and then refit the lower plug. Take off the upper plug (best to do this from the engine bay using a torque wrench) and fill it back up until the oil comes out of the fill hole (when the car is sat on level ground). It takes about 3.1 litres of oil (check the specs) so you need to buy 4 1litre bottles of Redline 75W90 (or similar). Refit the upper plug. Job done.