Got an old Belarus 250AS. Been a good cheap Model A workhorse. It simple and got the job done.
Hydralic Oil. Its time to change it again. The Ruskys Operation Manual calls for 30wt Motor Oil. They built this Tractor to work on Collective Farms so it as simple as possible Fuses are a length of diffrent size wires. That simole. The hydralics are a pump, Valves and a single Cylinder double action cylinder with a Screen Filter. I am thinking the 30 wt was used so they would not need to supply Hydralic Oil/Fluid.
Would Regular Tractor Hydralic Fluid Work. With this simple setup it seems it would be even better.
Use whatever they tell you in the manual. Those Belarus are simple, easy to maintain and indestructible. Their worse side is the electrics, is yours ground positive? A lot of people didn't know this and fried the system way back then.