A mixture comprising A) a copolymer comprising from about 70 to about 79% by weight of units derived from ethylene, and having (a) M.sub.w measured by gel permeation chromatography employing polystyrene standard ranging from about 50,000 up to less than 130,000 and/or (f) SSI.ltoreq.18; (b) density (D) ranging from about 845 to about 895 kg/m.sup.3; (c) M.sub.w/ M.sub.n less than 3; (d) melting point (T.sub.m) measured by differential scanning calorimeter ranging from about 15.degree. C. to about 60.degree. C.; and (e) degree of crystallinity.gtoreq.15%, and B) an amorphous polymer having M.sub.w ranging from about 130,000 to about 1,000,000 having degree of crystallinity.ltoreq.5%. In one embodiment the density and the melting point of the copolymer A) fulfill the expression T.sub.m.ltoreq.1.247 D-1037. In another embodiment, the percentage content (E: % by weight) of repeating units derived from ethylene and melting point (T.sub.m: .degree. C.) of the copolymer A) fulfill the expression 3.44E-206.gtoreq.T.sub.m. Also, additive concentrates and lubricating compositions comprising the components making up the mixture.