Hi-I live in a three family house that has three fuel tanks in the basement. The homeowners have only had the house for a year and don't speak much English. The other tenant and I can't get a straight answer about which tank belongs to which apartment. The one I am told is the other tenants has been at zero for 2 weeks, and their heat is still working. So I really have two questions, do the oil tanks have a 'fuel reserve'-like a car, that even when you're on 'E', you still have a few gallons in the tank? And second-how can we definitively tell which tank is which?
Thanks,
Kristina

To identify follow the 3/8 inch copper line from your burner back to your tank.

Usually when a tank is out of oil it is out of oil. Thete might be a few gallons left but due to the pitch of the tank the furnace cannot draw it out.