Apex Leisure confirmed that the correct gearbox oil for NSR's is a 'light' or a 10/40 'Gear oil'. ie not engine oil.

Pop to your local dealer see what they sell, I'd tend to go for a m/bike specific semi/fully synth branded oil.

Could talk individual brand's all day but is one any better than the next, if so how do ya know if it meet's the same spec???

Phil