Diesel Cetane Rating I'm still seeing a large amount of people that want to continue adding cetane boosters to the 2 cycle oil this is not required. Today diesel fuel is approximately 43 - 47 cetane number. Please check over on the MSDS page. Cummins Cetane Requirements for 1st, 2nd and 3rd Gen Trucks A Cetane rating of 40 is recommended at temperatures above 3