rh, I work for Petro Oil but I fix computers, I don't know much about oil usage. Who's your oil company? If it's not us, it should be.
Seriously, do you have a service contract? I believe our customer service reps are trained to answer questions like that; based on the size of your oil tank and something called a degree day (it calculates how cold it is and will be to figure out when you'll need your next delivery), they should be able to tell you how much is normal. If it's not normal usage, your guage might be faulty or you might have a bigger problem and they could take a look at it.
I rent a house and don't pay for heat so I've never been all that concerned about how much we use.