You do need a 17mm hex to undo the gearbox plugs, undo the top fill one before undoing the bottom drain to prevent dropping the oil then not being able to fill it back up. Most use redline MT90, last time I used this and the time before I used redline MTL, the MT90 seems to give a better shift buffer as its slightly thicker. Whatever you use it HAS to be GL4 don't get anything unless it states that its GL4. GL5 doesn't supersede it, it will destroy the brass synchros if you use it.