What do you mean "clears up in a few hours", is the oil completely clear like new oil? I had a 5 gal bucket of emulsified SAE 90 gear oil out of my VAC, it did not settle out with some clear oil on top for most of a summer.
Stir that used oil up and pour about a quart in a glass jar. Let set in the house (warm) for a couple days/week, if emulsified some water will show on the bottom.
Put some of your new oil in a glass jar with just enough water and shake to emulsified similar to the state of your used transmission oil and test the water finding paste.
Pic is what oil surface (90 wt) looks like after a short drive (still cold) and plus about 20 mins after pulling cover. Clean oil, no water.