TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The diesel composition comprises base diesel (balance), and additives (50-10000 ppm). Preferred Components: The weight ratio of component B and component A is 0.05:5-1. The composition B is p-phenylenediamine derivative antioxidant or hindered phenol antioxidant having tertiary butyl(s) on the o-position of phenolic hydroxy group; 4-10C dialkyl p-phenylenediamine(s); or and bisphenol antioxidant connected through methylene or sulfur. The component B is N,N'-di-sec-butyl p-phenylenediamine; N,N'-dioctyl p-phenylenediamine; N,N'-bis-(1-methyl heptyl)p-phenylenediamine; 2,2'-methylene-bis-(4-methyl-6-tert-butylphenol); 4,4'-methylene-bis-(2-methyl-6-tert-butylphenol); 4,4'-thiodiglycol-(2-methyl-6-tert-butylphenol); 4,4'-thiodiglycol-(2,6-tert-butylphenol); and/or bis-(3,5-di-tert-butylphenyl-4-carbonyl benzyl)sulfoether. The Mannich base ashless dispersant is obtained by reacting polyene alkyl phenol, aldehyde and amine at a molar ratio of 1:0.1-10:0.1-10 at 50-200 degrees C. The polyene alkyl phenol is of formula (I). The aldehyde is formaldehyde (preferably), acetaldehyde, propionaldehyde, butyraldehyde, valeraldehyde, hexanal, benzaldehyde, salicylaldehyde and/or p-formaldehyde. The amine is an organic amine of formula H-N(R1)-R2 (preferably polyamine). The additives further comprise a metal passivator. The weight ratio of component B and metal passivator is 0.01:10-1. The weight ratio of component A and metal passivator is 1:0.01-1. The metal passivator is amine salt formed by reacting triazole and alicyclic amine; or reacting triazole, formaldehyde and alicyclic amine through a Mannich reaction, Schiff base and organic polybasic carboxylic acid. The base diesel further comprises another diesel selected from petroleum diesel, Fischer-Tropsch synthesis diesel, hydrocracking biodiesel and/or oxygen-contained diesel composition. The volume ratio of biodiesel and another diesel is 1:0-99.R=polypropylene radical, polybutylene radical, polyisobutene radical (preferably) or polyethylene-allyl;R1-R2=1-30C alkyl or heteroatom containing 1-30C group; andheteroatom==OH, COOH, NO2, NH2, ester group, acyl, alkoxy, halo or amino.