Here is what I down loaded from prime mover skid steer. It wasn't your exact model, but it looks to me like they want 10w40. I'll try to make a shortcut to the manual. The hyd oil was on page 115. LOL I would use 10w40.
Keep the hydraulic system filled with one of the following:
• 10W40 SE or SF manufacturers suggested oil.
• Hydraulic fluid as recommended by equipment manufacturer, but the viscosity should not
drop below 50 SSU or contain less than .125% zinc anti-wear additives.
CAUTION: Do not mix oil types. Any mixture, or an unapproved oil, could
deteriorate the seals; Maintain the proper fluid level in the reservoir. When
changing fluid, completely drain old oil from the system. It is suggested also that
you flush the system with clean oil.
Recommended filtration 20-50 micron.
Maximum operating temperature 200 OF 193.3°el.