TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The composition (C2) containing ethylene amine and phenolic antioxidant further comprises an aromatic solvent (preferably aromatic naphtha solvent); an acidic chelating agent selected from dicarboxylic acid and a tricarboxylic acid; a detergent (D1) selected from a polyisobutylene succinimide, a polyisobutylene succinic anhydride or their derivative, a polyether compound, a polyether-polyol compound, and an epoxylated ester compound; an additive (A4) selected from cetane improvers, ignition accelerators, metal deactivators, corrosion inhibitors, thermal stabilizers, detergents, antiwear agents, and demulsifiers; and a fuel composition comprising a biodiesel solution (B1) and petroleum based diesel fuel (A5). The composition (C2) preferably comprises (wt.%): tetraethylenepentamine or pentaethylenehexamine (preferably tetraethylenepentamine) (50-80, preferably 75), propyl gallate (0-10, preferably 5), 2-tert-butylphenol (5-20, preferably 10) and aromatic naphtha solvent (5-30, preferably 10). The composition (C3) containing hydroxy dicarboxylic acid and at least one phenolic antioxidant further comprises a solvent selected from glycols, glycol ethers, glycol ether esters, alcohols, ketones, amides, and ethers (preferably propylene glycol or octanol); an amine (A3); detergent (D1); biodiesel solution; additive (A4); and petroleum based diesel fuel (A5). The composition (C3) preferably comprises 2-tert-butylhydroquinone, 2,3-dihydroxybutanedioic acid and an amine, especially comprises (wt.%): 2-tert-butylhydroquinone (2-40, preferably 5-40), 2,3-dihydroxybutanedioic acid (0.5-5), phenolic oxidant other than 2-tert-butylhydroquinone (5-20), amine (5-40), octanol (1-10), and propylene glycol (45-93.5). The compositions (C2) and (C3) comprises biodiesel solution (20-30 wt.%) and petroleum based diesel fuel (70-80 wt.%). The concentration of antioxidant composition is 20-2000 ppm. Preferred Components: The ethylene amine is selected from ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, aminoethylpiperazine, and heavy polyamine X (preferably tetraethylenepentamine or pentaethylenehexamine). The phenolic antioxidant (A1) is selected from alpha naphthol, butylated hydroxyanisole, butylated hydroxytoluene, ethoxyquin, gallic acid, dodecyl gallate, octyl gallate, propyl gallate, pyrogallol, 2-tert-butylphenol, 2,6-di-tert-butylphenol, 4,6-di-tert-butylphenol, 2,4,6-tri-tert-butylphenol, 2,6-diisopropylphenol, 4-sec-butyl-2,6-di-tert-butylphenol, and 2-tert-butylhydroquinone (preferably propyl gallate or 2-tert-butylphenol). The phenolic antioxidant (A2) is (A1) (preferably 2-tert-butylhydroquinone or a 2-tert-butylhydroquinone isomer, especially 2-tert-butylhydroquinone). The biodiesel solution is produced from a source selected from soybean oil, yellow grease, corn oil, rapeseed oil, coconut oil, peanut oil, palm oil, fish oil, marine oil, cottonseed oil, mustard seed oil, camelina oil, jojoba oil, hemp oil, tallow, poultry fat, lard, safflower oil, jatropha oil, algae oil, and sunflower oil. The hydroxy dicarboxylic acid is 2,3-dihydroxybutanedioic acid. The amine (A3) is selected from ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, aminoethylpiperazine, heavy polyamine X, N,N'-di-sec-butyl-1,4-phenylenediamine, 2-(2-aminoethylamino)ethanol, ethylenediaminetetraacetic acid, N-(2-hydroxyethyl)ethylene diamine-N,N',N'-triacetic acid, N,N,N',N'-tetraacetic acid, ethylenediamine-N,N'diacetic acid, diethylenetriaminepentaacetic acid, and trans-1,2-diaminocyclohexane. EXAMPLE - A composition comprising (wt.%): 2-tert-butylhydroquinone (20), 2,6-di-tert-butyl phenyl (5), tetraethylenepentamine (10) and tartaric acid (1) were prepared. The composition showed an induction period (IP) of 16.27 hours, indicated that it was effective for stabilizing the biodiesel.