I've had oil foam up on me, too ... but, it wasn't due to water. The presence of water only seems to create "popping" of the oil, not foaming.

If I remember correctly, the foaming incidents occurred when old/new oil were combined ... and possibly they were two different types.
I use Olive Oil, for some things, and Canola blends for others ... and it seems to me that I may have added one to the other, to raise the level of oil, when the foaming incidents occurred.

Could this have been the same scenario in some of your situations ???

... cp