The reason this stuff still exists (I bought 15 gallons at $16 each bucket at Atwoods) is because it works fine in very old, "simple" hydraulic systems... like an old log splitter, or old tractor loader.
Simple gear pump -> hoses -> spool valve -> hyd cylinder -> return = this stuff is OK for it.
It definitely has the "old tractor hyd fluid smell" - it's distinctive.