My wife and I just reevaluated what we think our oil consumption will be this winter-- we had been thinking a tank and one half, but with the temperatures we have been achieving in the house with the woodstove, we think we might be closer to just a tankful (our tank is 250 gallons-- saving a half a tank would be big savings).

We have one of those outdoor weather stations with two monitors in the house.  One monitor is by the window in the bathroom on the other side of the house from the wood stove, it has been 73 degrees the past few nights.  I haven't measured the living room temperatures, but I would swear we are above 80 degrees.

We haven't even run the heat yet this season (where we had last year at this time)-- You really can offset the oil bill with a good fire.