Which oil in the all synchro (post 1965) gesrbox with OD

Saloons
1

Not MTL, and not the original straight SAE 30.
10-50 mineral engine oil is too thick I think, causing a delay in the OD engaging.
Or what do others have to say?
Peder

2

Workshop manual and owner’s manual both specify EP90.

3

I would use Redline MT90 and see how it goes. It works well with the all synchro E Type boxes and I don’t think that there is anything in a Laycock de Normanville overdrive that would be upset by it.

4

I use Redline MT 90 in my 4 speed o d. And it works great. I’ve put 2000 miles on and counting since I started using it.

5

Ive used Shell Spirax 80/90 the last two years with no negative issues