COMPOSIZIONI LUBRIFICANTI A BASSE EMISSIONI DI PARTICOLATO PER MOTORI A COMBUSTIONE INTERNA

A lubricant which inhibits the emission of particle mixtures from an internal combustion engine, especially a diesel engine, comprises: (a) 2-25 wt.% additives (b) 0-20 wt.% polymer to improve the viscosity index, and (c) a base containing (1) oil-soluble esters, (2) oil-soluble copolymers of unsaturated esters and olefins, (3) oil-soluble polyglycols and/or (4) hydrocarbons selected from (4a) oligomers of internal, linear, branched or cyclic olefins and/or alpha -olefins and (4b) hydrogenated, optionally isomerised mineral oil base, and (5) 0-85% mineral oil base with respect to the total amount of products (1) to (5). The lubricant preferably contains 5-15 wt.% additive and 1-12 wt.% viscosity index-enhancing polymer. The base contains 0-40, especially 0 wt.% mineral base oil. The esters (1) are carbonates and esters of polyols. The polyglycol (3) is polypropylene glycol. The lubricant especially contains 10-20, more especially 14-18, wt.% neopentyl polyol esters, 3-7, more especially 4-6, wt.% viscosity index-enhancing polymer and 12-18, especially 13-16, wt.% additives, and the rest C10 poly- alpha -olefins.