Question: what is number 1 diesel?
Answer: Standard diesel fuel (sometimes called diesel oil) comes in two grades: Diesel #1 (or 1-D) and Diesel #2 (or 2-D). The higher the cetane number, the more volatile the fuel. Most diesel vehicles use fuel with a rating of 40 to 55. ... Diesel #1 flows more easily than Diesel #2, so it's more efficient at lower temperatures.