1976 Beall hot oil tanker...anyone with experience to help with valve operation?

I just purchased a 1976 Beall hot oil trailer to haul water and liquid fertilizer on the farm etc. Not sure the last time it hauled oil but the valves are all sticky and don't want to move. Can any one help with the operation of the old Knappco hot oil safety valve? It has a crank on the top of the tanker and I think...a safety release on the bottom, but not sure of how much of the old oil I'm fighting or if I'm operating the valve properly.

 

stick a steam line in the valve and warm it up first...

 

Or a propane torch... asphalt oil?

 

Hopefully you got a screamer of a deal on that trailer as an insulated tanker thats coated in sticky oil dosent seem like a good fit for hauling water or fertilizer. Its heavier then needed sense its insulated. A stainless double conical center drop that could stand being pumped off or blown off with air pressure would have been a better choice.