Soluble chemicals, called additives, are mixed in gasoline to improve its performance characteristics. Additives are petroleum-based raw materials. They have very specialized chemistry/function. The concentration of additives is in the ppm (parts-per-million) range. One ppm is equivalent to one mg per kg. The additives do not enhance the octane rating of gasoline. They serve only as lubricants and facilitate improving efficiency. This topic will discuss the types and properties attributed by various additives to gasoline blends.