Steve,
I notice no one is replying to you so thought I had better respond before I get on the plane across the pond later tomorrow.
The separator's I have restored all have thin hydraulic oil in them, I have some original separator oil in a M-H can and it is very thin and comparative to our current hydraulic oil, not that my separator's will ever get up to full speed, but thin oil does make them turn easier.
Hope the M-H separators will soon be busy in Wisconsin in preparation for the strawberries and "thick Jersey cream" at the banquet. Looking forward to some quality strawberries as ours are almost done for this season with it being so wet.
Malcolm.