My 584 sleeps out side and it can grow hydro oil from condensation. I found out the hard way when the filter got full stuff and the hydraulics quit acting right. Now it get annual oil change regardless of hours.
mine hangs outside in the summer but when it gets fall and winter it goes to the shop (gets tough to start at -40 LOL)
I guess after 10 yrs its bound to build up some
it gets oil and fuel filter change every fall guess I better keep a eye on hyd from now on