same as the main engine. we use delo gold ultra 15w40 in our machine. most oils today are dual service. most of the major oil companies have a tech advisory service who can give a recommendation. many also have product guide apps for android and iOS.
according to thier recommendation you can use in the engines the transmission and the hydraulics.
"i reject your reality and substitute my own" - adam savage. i suspect my final words maybe "well shit, that didnt work"
instead of perfection some times we just have to accept practicality