castrol gtx vs 4 stroke 10w-40

[noid]

So i need some oil for the tranny and i usually use castrol gtx 10w-40 but have also seen "Castrol 4-Stroke Motorcycle Oil" which is better/ which should i use?

 

[beastsr20]

I use royal purple 10w-30 car engine oil in my gearbox.

I know your not suppose to because of the friction modifiers in the synthetic oil, but hey I had to split the crankcase cause of a piston problem and everything in the gearbox side looks brand new, no problems with any gears or bearings and I beat the sh*t out of it. Didn't pull the clutch apart, but its the same clutch from 2001,

 

[underwaterboy82]

i use 20w-50 havilon and havnt had any issues

 

[03blasteryfs03]

i use snythectic 80w