Boxy,
I've always just used EP 90 in everything on the 2A, and its been fine.
That is what the civvy manuals recommend as well, no fancy 80-140 around in those days I guess!
Using the same oil for everything is a bit simpler as well, I usually get in in a 20 litre drum.
How is the 2A coming along?
Cheers,
Mike.