which gearbox oil should i use?

[aaronng]

sorry im still abit noob at this.. which one would be a thicker oil.. higher the number or lower? 75w80 or 75w90 etc..

and my cars done 58,xxx kms.. and my friend recommended the castrol one.. any experiences with the castrol transmission oil?

The first number is viscosity at cold temperature, the second number is viscosity when the gearbox is warmish.

If it is 75w80 and can be used with manual synchromesh gearbox, then you can use it.