The invention relates to a fuel preparation for use in diesel engines consisting of plant oil mono-alcohol esters and up to 20 weight percent linear and branched paraffins and olefins of chain length C5-C11 and alcohols of chain length C2-C8, whereby the paraffins, olefins and alcohols are obtained by means of gasification of biomass and subsequent Fischer-Tropsch synthesis not involving any processing of the Fischer-Tropsch fraction by means of hydrogenating procedures and the preparation has a flash point >55° C. and a density >820 kg/m3.