I know there has been much talk of different types gearbox oil to use and most people say that red line seems to be the best
I have been looking at the red line range and was wondering which type off oil viscosity is the one to use in Manual 8v H Reg

1: 75W80W GL-4
2: 75W90 GL-4 mt 90
3: 70W80 GL-4
or if theres another type that I have missed
cheers
gteyes