A lubricating oil composition comprises a major amount of an oil of lubricating viscosity to which is added a minor amount of an oil soluble ashless dispersant, an oil soluble overbased metal detergent, an oil soluble sulfur and/or phenolic antioxidant and/or aromatic amine anti-oxidant. A lubricating oil composition (I) comprises a major amount of an oil of lubricating viscosity to which is added a minor amount of an oil soluble ashless dispersant, an oil soluble overbased metal detergent, an oil soluble sulfur and/or phenolic antioxidant and/or aromatic amine anti-oxidant. The surfactant system of the metal detergent is derived from at least one or at least two different surfactants (preferably a salicylate). The total base number of the composition is at least 10 (preferably at least 20) and the viscosity index is at least 90 (preferably at least 100, especially at least 105). An independent claim is also included for lubricating a marine diesel engine by supplying (I) to the engine.