580K (Early) hydraulic fliud (Motor oil?)

I just replaced some old hydraulic hoses on my early 580K farm hoe, and I'd like to do a total change out of the hydraulic fluid, including opening the clean out hole in the reservoir to get all old junk that may be present. I recently found that Case recommended 10W30 API CC motor oil as the hydraulic fluid of choice when the unit was new (can see at http://ift.tt/1NJidJK). Now Case wants me to use HyTrans. I see on here a number of folks recommend AW32. I've found an old, still sealed 55 gal drum of Citgo SAE10 motor oil with API CC,CD/SF,SE for $100. I've read the other posts on this subject. Those of you who think AW32 is just fine for my hydraulics, what do you think of this SAE10? Also, I can't think of a reason a sealed drum of oil would have any problems - correct, or short sighted?

580K (Early) hydraulic fliud (Motor oil?)