US Patent 8183192 Lubricating oil additive and lubricating oil composition containing same

An overbased salt of an oligomerized alkylhydroxyaromatic compound for use in a lubricating oil composition is disclosed, wherein the alkyl group of the alkylhydroxyaromatic compound is derived from an olefin mixture comprising propylene oligomers having an initial boiling point of at least about 195° C. and a final boiling point of greater than 325° C. and up to about 400° C. as measured by ASTM D86. Also disclosed is a propylene oligomer having an initial boiling point of at least about 195° C. and a final boiling point of greater than 325° C. and up to about 400° C. as measured by ASTM D8, wherein the propylene oligomer contains a distribution of carbon atoms that comprise at least about 50 weight percent of C14 to C20 carbon atoms.