I remember reading somewhere that ethanol was really bad, but I could be wrong. I do know, by the laws of chemistry, that alcohol and water are soluble. So, by nature, if you have any moisture in your oil, the ethanol will be sought out by the polar water molecule and the two will dissolve and separate from the oil blend by creating a heavier molecule or compound. This could create a good scenario in a settling drum and a bad one at any point after.