Lubricating compositions containing sulphonates and phenates

摘要

A lubricating composition containing (a). at least 3 weight percent of an overbased sulphonate detergent with a metal ratio of 12.5:1 to 40:1; (b). at least 1.5 weight percent of a sulphur containing phenate detergent with a metal ratio of not more than 2.5; and (c). an oil of lubricating viscosity, wherein the sulphur containing phenate contains oligomers of hydrocarbyl phenol with at least 50 wt % of said oligomers in the form of the tetramer or higher oligomers. The composition is suitable for internal combustion engines, particularly marine diesel applications to provide improved cleanliness decreased cylinder wear and reduced deposits.