Torque converter

Locomotives need a way to apply power to a load (of cars), exerting a force on the load until the rolling friction is broken and the cars start to move. You dont want to do this by 'slipping the clutch'. In our Whitcomb gas mechanical loco the power is exerted through a torque converter. Whitcomb called it Hydro-Motive. I so fortunate to get a copy of the operation instructions for the Twin disc torque converter. The torque converter is basically two fined plates which operate in oil. The instructions recommend light turbine oil or 10 wt oil. I am planning on using 10 wt. hydralic oil. Our model is a 24 HU-00 which takes 18 gals of oil. The book says to fill it until oil comes out of the fluid over flow level hole. Apply a small amount of lubricant through the fittings every 50 hours. I wonder when that was last done ? I hope that the seals are still good after 67 years.