Gearbox Oil

650ml of 10w30 motor oil, (no friction modifiers), ATF type F, or a specific oil designed for motorcycles with wet clutches.
 
so pennzoil 10w 30 of 650ml will work? Why do i get oil leaking from my gearcase over flow tube???
 
so pennzoil 10w 30 of 650ml will work? Why do i get oil leaking from my gearcase over flow tube???

did you check the level in the sight glass, below the brake pedal ???
should be between the min./max. lines
 
so pennzoil 10w 30 of 650ml will work? Why do i get oil leaking from my gearcase over flow tube???

Too much oil.

Leaky crankcase seal.

Overheating.

650ml of oil no more, no less!

It is not the overflow tube, it is the breather tube, and should run up under the tank and terminate near the handlebars, under the hood.