Diesel or Petroleum usually has the same colour all over the country, but by dyeing your own fuel with a distinctive colour you can easily identify whether a particular sample of diesel comes from your own stores. Furthermore, thieves who are successful in stealing your fuel may not try to steal from you again when they realise that no one buys dyed diesel in large quantities. When thieves and employees realise that the diesel is dyed, they are more likely to be dissuaded from attempting to steal your stockpile of fuel again.