Standard diesel fuel (sometimes called diesel oil) comes in two grades: Diesel-1 (D1) and Diesel-2 (D2). Diesel or Diesel fuel in general is any fuel used in diesel engines. Thatâs why itâs also commonly called as AGO or Automotive Gas Oil. Diesel fuel is a type of fuel derived from the distillation of oil that is heavier than gasolighter than engine oil and heavy oil. D1 is similar to kerosene and is lighter than D2. While D2 is sold most of the time, D1 is sold during winter in very cold climates and not sold in hot weather countries. But D2 is easily available in most countries around the world. Despite rising awareness of environmental protection, D2 remains to be a key type of fuel for use in vehicles in many countries. In particular, demand for D2 has risen significantly in Asia over the past years as a consequence of increasing of cars. In view of the country sustained economic growth, D2 will continue to be under-supply in the China/India and market.