have you changed the hyd oil since you got it?
how many hours have you used it?
if it's not new / just serviced I'd change and put in something I'm familair with / can top off with.. like a UTF fluid inthe hyds.
as for the rear and tranny.. check if it wants utf or gear oil.. many like gear oil.
if you don't want to change the oil, and need to top the hyd resv off.. hard to go wrong with utf fluid... should be ok to top off a sump, even if it had a plain hyd oil in it..
soundguy