TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The composition further comprises an oxygenated detergent additive. The composition further comprises: metal deactivator, detergent/dispersant different from the detergent comprising a quaternary ammonium salt of polyester, antioxidant, corrosion inhibitor, a foam and/or antifoam inhibitor, demulsifier, agent improving the cold flow, lubricant, and/or additive against valve seat recession. Preferred Components: The fatty carboxylic acid has the structure of formula (R1-CH(OH)-R2-C(=O)-OH), where the compound has an oxygen or nitrogen atom capable of condensing with the acid and further has a tertiary amino group of formula (R4-NR3-R5-X1-H) (II). The carboxylic fatty acid is 12-hydroxystearic acid, ricinoleic acid, 12-hydroxydodecanoic acid, 5-hydroxydodecanoic acid, 5-hydroxydecanoic acid, 4-hydroxydecanoic acid, and/or 10-hydroxyundecanoic acid, where the compound having an oxygen atom or nitrogen capable of condensing with the acid further comprises a tertiary amine group, which is N,N-diethylethylenediamine, N,N-dimethylethylenediamine, N,N-dibutylethylenediamine, N,N-dimethyl-1,3-diaminopropane, N,N-diethyl-1,3-diaminopropane, N,N-dimethylaminoethanol, and/or N,N-diethylaminoethanol. The polyester quaternary ammonium salt comprises a salt of quaternized polyester amide, where the polyester containing tertiary amine group used to prepare polyester quaternary ammonium salt is a polyester amide containing tertiary amine group. The dispersion comprises particles consisting of an iron compound in amorphous form. At least 85%, preferably at least 95% of particles dispersed in the organic phase are individualized particles. The particles of the dispersion have a phi 50 of 1-5 nm, preferably 3-4 nm. The dispersion comprises particles consisting of an iron compound in crystalline form. The organic phase of the dispersion is based on apolar hydrocarbon. The amphiphile is a 10-50C, preferably 10-25C carboxylic acid. The average size (DDRX) of particles constituted of an iron compound in the crystallized form, measured by X-ray diffraction is less than or equal to 12 nm. At least 80% by number of particles have a size (DMET) of less than or equal to 12 nm measured by transmission electron microscopy, preferably less than or equal to 6 nm. The particles have a median diameter ( phi )50, preferably 4-10 nm. The particles have a hydrodynamic diameter (Dh) of less than or equal to 50 nm, preferably less than or equal to 20 nm, measured by dynamic light scattering. The content of iron is 0.05-25 wt.%, preferably 2-15 wt.%.R1 = H or 1-20C hydrocarbyl group;R2 = 1-20C hydrocarbylene group;R3, R4 = 1-10C hydrocarbyl group;R5 = 1-20C hydrocarbylene group;X1 = O or NR6; andR6 = H or 1-10C hydrocarbyl group.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The polyester quaternary ammonium salt comprises the reaction product of: (a) a polyester containing tertiary amine group, comprising the reaction product of a fatty carboxylic acid containing at least one hydroxyl group and a compound having an oxygen atom or nitrogen capable of condensing with the acid and further having a tertiary amino group; and (b) a quaternizing agent suitable for the conversion of the tertiary amino group into a quaternary nitrogen, where the agent is dialkyl sulfates, benzyl halides, carbonates having hydrocarbyl-substitution; and hydrocarbyl epoxides in combination with an acid or its mixtures. The polyester quaternary amide salt comprises an anion of formula (R7-(-O-CHR1-R2-C(=O)-)n-NR6-R5-N+(R3)(X2)-R4) (III). The oxygenated detergent additive is a polyisobutylene compound comprising head group of succinic anhydride or succinic acid. The mass content of iron is 1-50 ppm, preferably 2-20 ppm of iron metal with respect to the total mass of the fuel.n = 1-10;R7 = H, 1-22C hydrocarbyl group or 1-22C hydrocarbyl group; andX2 = a group derived from quaternizing agent. EXAMPLE - Ferric nitrate (576 g) was mixed with ferrous chloride tetrahydrate (99.4 g). The mixture was completed with distilled water to one liter of solution. The final concentration of the iron precursor solution was 1.5 mole/l in iron. Sodium hydroxide pellets (240 g) were diluted in distilled water to make one liter of sodium hydroxide solution (6 mole/l). In a one liter reactor equipped with a stirring system, a base stock of sodium nitrate (400 ml) having 3 mole/l was introduced. The pH of the solution was adjusted to 13 using a few drops of sodium hydroxide solution. The formation of the precipitate was effected by simultaneous addition of the precursor solution of iron and the previously prepared solution of sodium hydroxide. The feed rates of these two reagents were adjusted so that the pH was kept constant and equal to 13 to ambient temperature. The solution obtained by precipitation (21.75 g of ferric nitrate and 0.27 mole of iron), previously neutralized were redispersed in a solution containing isostearic acid (24.1 g) and Isopar L (RTM: Isoparaffin fluid) (106.4 g). The suspension was introduced into a jacketed reactor equipped with a thermostatic bath and equipped with a stirrer. The entire reaction mixture was heated to 90 degrees C for 4 hours. After cooling, the mixture was transferred into a test tube and an aqueous phase (500 ml) and organic phase (100 ml) were recovered. The resulting product was dispersion of particles of iron. Non-quaternized polyester amide salt was reacted with 2-ethylhexanol, acetic acid and propylene oxide at 90 degrees C to obtain detergent composition. The dispersion of iron particles and the detergent composition were mixed at room temperature to obtain composition.