| abstract |
The present invention provides overbased detergents as lubricating oil additives effective for the lubrication of mechanical components in land and marine engines, such as, for example, hydraulic systems, transmissions, two-stroke and four-stroke vehicular engines, trunk piston and two-stroke crosshead marine engines. These overbased detergents lead to improved detergency and thermal stability performances versus high overbased sulfonates. Moreover, they are more compatible with commercial phenates than conventional sulfonates. The overbased detergent is obtained by the process of (I) preparing a surfactant system comprising an alkyl aromatic sulfonate and an alkylphenol or an alkylhydroxybenzoic acid derivative and (II) reacting the surfactant system with a source of alkaline-earth metal and an acidic co-agent. |