Advice needed on right gearbox oil for 68 roundtail spider

[Rad alfa]

Hi there, I have brought over from the uk a 68 spider junior. I had it serviced recently and the gearbox fluid changed. The gearbox change is now awful. When cold it is impossible to engage second from first (lots of gear crunching), after a few minutes all is well so I assume it points to an issue of viscosity at low temperatures. I know the original spec was shell spirex 90 EP which is no longer available. Can anyone tell me what the right local equivalent is? I suspect this is the issue.
Thanks!

[Steve S]

The original fluid is now obsolete but since they specified an SAE90 the modern equlivent would be a 80w90 or better, a 75w90 which will be full synthetic. 75w85 is a popular grade these days to improve cold shifting. I wouldn't have a problem using this, the viscosity difference is minimal and they are usually recommended where 80w90 is spec. Although I don't know what the syncros are made of I would stick with a GL-4 over a GL-5.