Hi, I am new and would like to say, this is a great site for information. I just picked up a 59 Fordson Power Major, what a great old tractor. Anyway, I drained the gear box and diff/hydraulic and would like to know if rotella 15w40 would work in them? I searched and found most around here use a 30w, but I have not found any oil at the local store. They carry a universal trans-hydraulic oil, but it is only a 10w20. Any info would be helpful. Thanks, Rick