While #2 heating oil is the most common fuel oil used in residences and commercial buildings, kerosene can be used in its place. Kerosene is the purest and cleanest burning of the three most popular fuel oils used for heating, which are #2 heating oil, blended heating fuel and kerosene.
The least-refined fuel oil produced is #2 heating oil, and is therefore the cheapest. Because it is unrefined, the particulates cause it to gel up at lower temperatures. Because kerosene is the most refined fuel oil available, it can be subjected to much lower temperatures than #2 heating oil. Blended heating fuel is an even mix of kerosene and #2 heating oil.