I believe that the trans and differential can take either gear oil or UTF. Most people on this forum recommend the UTF to prevent cross contamination if you get any leaks between them and the hydraulic sump. The hydraulic sump should get UTF that meets the Ford/New Holland 134D specification, and you should use the same in the trans and diffy if you go that way.
If you are going to use gear oil, I would use 80W90 rather than straight 90wt. The tractor will thank you on those cold winter mornings.
That's why I was asking I was told to use trans hydraulic in the trans and differential along with the lift assembly.I remember my dad's tractor had 90wt in the trans because once I parked it on a downhill slope for some reason and 90wt leaked out.
So the trans hydraulic fluid will be heavy enough for the differential?
I bought 5 gallon of trans hydraulic fluid at the local farm&feed store that was supposed to have more additives,it was $10 higher than the normal trans hydraulic fluid.
I assume UTF is trans hydraulic fluid?
Hi the 641 Owners manual calls for 80W in the trans and differentiable, summer and winter UTF(universal Tractor Fluid) will work if all you are doing is mowing but if plowing digging discing hard work I would stick with the 80w gear lube.
Hyd system the UTF would be fine.
GB in MN