Is it true ethanol breaks down long hydrocarbon chains into shorter ones?

I'm thinking the crud in the bottom of my heating oil tank must be long chain hydrocarbon. I can't get my tank refilled for 3 days, so was thinking of dumping a gallon of ethanol down and letting it sit (unused) until they add another 200 gallons of #2 heating oil to it. Good or bad idea? Would it cause any problems in such a low concentration?