Which Gearbox Oil ?

[S5TVR]

I've noticed that the gear change on my Chim is smoothest from cold. As the car gets warmed up it deteriorates slightly. Could it be that the gearbox oil is not of the optimum viscosity ?. If anyone else has experienced this I would appreciate your thoughts and any you might have on choice of oils to use.

[Paul (93 Chim)]

Hi,

I've just changed my RV8 gearbox oil for Castrol SMX-S which was recommended to me, but there is no change to the old stuff, still good when it's cold, but notchie when hot.

Paul.