Tractor oils.

[Pilatus]

How does one cross reference tractor manufacturers own oil spec back to open market equivalent?
I have an old( new to me) Ford 3910H tractor , the oil in the back axle/ transmission/ hydraulics is very low, operators manual says oil is Ford M2c-86-b oil or M2c-159-a/b or M2c-134-B/C, a non Ford equivalent is not specified. Any help appreciated

 

[Thomas5060]

Its just a 10w30 oil. Multi G is the NH name for it.

 

[forblue]

Multi-G was not the original oil that was multi-F a thicker oil, unfortunately i was informed that this is being discontinued but suggest you use a universal farm oil which will do engine and back end.