I am a little confused as to which oil I should use to top the gearbox up. Haynes says that I should use a 10/40 a2 to top up but the gearbox oil is MTF-94. Should I use the MTF-94 or a 10/40 a2?
10w/40 for top up only if MTF94 isn't available. MTF94 for an oil change. If you have MTF94 then use it.
If you have MTF94, it's better to change it as it ages noticeably
