| abstract |
Lubricating oil compositions providing superior soot dispersing characteristics, which contain a combination of a high molecular weight dispersant and a soot dispersant comprising a linked aromatic oligomer of the formula (I) wherein each Ar independently represents an aromatic moeity selected from polynuclear carbocyclic coieties, mononuclear heterocyclic moieties and polynuclera heterocyclic moieties, said aromatic moiety being optionally substituted by 1 to 6 substituents selected from H, -OR1, -N(R1)2, F, Cl, Br, I, -(L-(Ar)-T), -S(O)wR1, -(CZ)x-(Z)y-R1 and (Z)y-(CZ)x-R1, wherein w is 0 to 3, each Z is independently O, -N(R1)2 or S, x and y are independently 0 or 1 and each R1 is independently H or a linear of branched, saturated or unsaturated hydrocarbyl group having from 1 to about 200 carbon atoms, optionally mono- or poly-substituted with one or more group selected from -OR2, -N(R2)2, F, Cl, Br, I, -S(O)wR2, -(CZ)x-(Z)y-R2 and -(Z)y-(CZ)x-R2, wherein w, x, y and Z are as defined above and R2 is a hydrocarbyl group having 1 to about 200 cargon atoms; each L is independently a linking moiety comprising a carbon-carbon single bond or a linking group; each T is independently H, -OR¿1?, -N(R1)2, F, Cl, Br, I, -S(O)wR1, -(CZ)x-(Z)y-R1 or (Z)y-(CZ)x-R1 wherein R1, w, x, y and Z are as defined above, and n is 2 to about 1000; wherein at least 25 % or aromatic moieties (Ar) are connected to at least 2 linking moieties (L) and a ratio of the total number of aliphatic carbon atoms in the oligomer to the total number of aromatic ring atoms in aromatic moieties (Ar) is from about 0.10:1 to about 40:1. |