Hi, Mark. When I worked at a bulk plant, the #2 heat oil and the #2 Diesel came out of the same tank. The only difference was the price. If it was sold as Diesel, it had the road taxes in the price. If your furnace is set up for #2 heat oil though, you want to use #2 Diesel. Much of the Diesel fuel sold at this time of the year is #1 or a blend with #1 for better cold starting of engines. Stick with the #2 if at all possible.