Abstract: Trunk piston marine engine lubrication, when the engine is fueled by heavy fuel oil, is effected by a composition comprising a major amount of an oil of lubricating viscosity containing at least 50 mass % of a basestock containing greater than or equal to 90% saturates and less than or equal to 0.03% sulphur or a mixture thereof, and respective minor amounts of an over-based metal hydrocarbyl-substituted hydroxybenzoate detergent other than such a detergent having a basicity index of less than two and a degree of carbonation of 80% or greater and 5 to 500 mass %, based on the mass of detergent, of an oil-soluble alkyl-substituted substituted phenol other than a hindered phenol. Asphaltene precipitation in the lubricant, caused by the presence of contaminant heavy fuel oil, is prevented or inhibited.

Abstract: Trunk piston marine engine lubrication, when the engine is fueled by heavy fuel oil, is effected by a composition comprising a major amount of an oil of lubricating viscosity containing at least 50 mass % of a Group II basestock, and respective minor amounts of an overbased metal hydrocarbyl-substituted hydroxybenzoate detergent other than such a detergent having a basicity index of less than two and a degree of carbonation of 80% or greater and 5 to 500 mass %, based on the mass of the detergent, of an oil-soluble alkyl-substituted phenol other than a hindered phenol. Asphaltene precipitation in the lubricant, caused by the presence of contaminant heavy fuel oil, is prevented or inhibited.

Abstract: A method of improving the compatibility of an overbased detergent with other additives in a lubricating oil composition. The method includes the step of adding an oil-soluble, hydrocarbyl sulphonic acid to the detergent.

Abstract: A method of improving the stability of a detergent or of improving the compatibility of a detergent with another additive in a lubricating oil composition. The method includes the step of reacting the detergent with a water-soluble ?,?-unsaturated carbonyl compound.

Abstract: A silencer for an idle air bypass valve in an internal combustion engine includes a grid disposed between the outlet of the idle air bypass valve and the intake manifold. The grid acts to reduce the air velocity entering into the intake manifold which dampens the vibration of a plastic manifold, thereby reducing noise generated.