Refinement Cracking Spread Date 08/04/1405 The graph above shows the trend of the cracking index of the refining industry from 1400 to the present day. It is worth noting that: 1 In calculating this index, an average of the production mix (diesel, gasoline, heating oil, oil) of industrial companies is considered. 2 The basis for calculating the cracks index is the average oil price of Brent, Dubai and Oman. 3 To select the quality of each of the products, the most recent crack propagation report prepared by the Industry Tables and Publishers Rating Department was used. 021-8445.