THIS WORK IS AIMED AT SYNTHESIZING OF SOME HIGH COPOLYMERS AND TERPOLYMERS WHICH CAN BE USED TO IMPROVE VISCOSITY INDEX AND DEPRESS POUR POINT FOR LUBRICANTS. IT CAN BE A MERIT IF THESE POLYMERS ACQUIRED HIGH SHEAR STABILITY UNDER ENGINES OPERATION CONDITIONS. THE STUDY IS OCCURRED TO PRODUCE COPOLYMERIC ADDITIVES VIA BINARY COPOLYMERIZATION OF STYRENE WITH OCTYL METHACRYLATE (OCMA), DODECYL METHACRYLATE (DDMA), OCTADECYL METHACRYLATE (ODMA) MONOMERS AND TERPOLYMCRIZATION OF STYRENE WITH MIXTURE OF ALKYIRNETHACRYLATES MONOMERS IN DIMETHYL FORMAMIDE (DMF) AS SOLVENT, USING BENZOYL PEROXIDE AS A FREE RADICAL INITIATOR OVER A WIDE PROPORTIONAL RANGES.THE COPOLYMERIZATION AND TERPOLYMERIZATION WERE CARRIED OUT AT 75 -C FOR A TIME OF 4-7 HOUR. PERFORMANCE EFFICIENCY OF THE SYNTHESIZED COPOLYMERS AS VISCOSITY INDEX IMPROVERS AND/OR POUR POINT DEPRESSANT WAS INVESTIGATED AND COMPARATIVELY EVALUATED WITH COMMERCIAL AVAILABLE VISCOSITY INDEX IMPROVERS, WHICH SHOWED THAT SHEAR STABILITY INDEX (SSI) OF 2% WT. OF THE SYNTHESIZED (STY-DDMA) COPOLYMER DISSOLVED IN MIXTURE OF BASE OILS (80% OIL 260/290 & 18% BRIGHT STOCK) IS 16.9 @100 ?C ARE BETTER THAN COMMERCIAL AVAILABLE ONES BASED UPON STYRENE-ISOPRENE COPOLYMER (IS 25 @100