as others have said you must use the proper oil, it protects the transmission bearings, if your tractor still has the old bronze bearings.
most get all concerned about the hyd system, most hyd oils will work in your hyd system, but it is your trans that you have to worry about.
just do not change the oil until you do your homework and be sure you use the proper oil.
when Arco (was AC) bought MF
i ask for trans/hyd oil for my old to35, young kid tried to sell me some type oil that they used in the AC tractors, because that is what they had.
I told him i did not want wd45 AC oil for my ferguson,
they ordered the proper oil (gl-1) and the kid was taught a good strong lesson from his boss.
You can not just pour anything into a old fergy.