Abstract: A process to prepare a kerosene and a gasoil product from a crude petroleum source having a Watson characterization factor K value of equal or below 12.0 by (a) isolation of a petroleum derived kerosene fraction and a petroleum derived gasoil fraction from said crude petroleum source, wherein the petroleum derived kerosene fraction has a smoke point of below 25 mm or below 19 mm if naphthalenes content of the kerosene fraction is below 3% vol and the petroleum derived gas oil has a cetane number of below 50 or a density higher than 845 kg/m3, ( ) adding a Fischer-Tropsch derived kerosene fraction to the petroleum derived kerosene fraction in an amount sufficient to obtain a mixture having a smoke point value of above 25 mm or above 19 mm if the naphthalenes content of the mixture is below 3% vol and (c) adding a Fischer-Tropsch derived gas oil fraction to the petroleum derived gasoil fraction such that the resultant mixture has a cetane number value of above 51.