Need to add hydraulic fluid. Not sure exactly what fluid it has in it. Is standard 46 hydraulic fluid okay to add to unknown fluid or best just to do full drain/fill?
In my opinion, since you don't even know what fluid is in it, you also don't know how old it is. So drain it all, and refill the whole system.
Why is the fluid level low?
be 46 were you are be in operator hand book