Some differences between kerosene and other combustible oils are its price, which can be significantly higher than other oils, the possible addition of fragrances or deodorants to the product and a specific gravity, or relative density to water, which is less than other fuel oils except gasoline. Kerosene's heating value, or heat content, is 135,000 British thermal units, or BTUs, per gallon, compared to number 2 fuel oil's 139,400 BTUs per gallon rating, but kerosene's heat content is greater than 43,000 BTUs per gallon compared to propane gas.
Kerosene is sometimes referred to as "lamp oil" or "coal oil." The second term is technically incorrect because kerosene is not made from coal; it is a petroleum product. Kerosene is made from number 1 fuel oil by filtering it to a higher standard. Bringing kerosene up to a much higher filtration standard and treating it to a water-removal process produces jet fuel type A.
At a cloud point rating of -40 degrees Fahrenheit, kerosene can continue to flow at lower temperatures than number 2 fuel oil or diesel oil, which can begin to form visible crystals at 16 degrees. When a fuel oil's cloud point temperature is reached, the heating system can begin to be affected. This is also referred to as "waxing" or "gelling." Cold filter plugging occurs when low temperatures cause a fuel oil to stop flowing. Kerosene's lower cloud point make it a better fuel source for outdoor cooking and heating under adverse temperature conditions, such as for use in the portable stoves and heaters carried by mountain climbers.