A lubricating oil composition comprising: an oil of lubricating viscosity in a major amount; an oil-soluble or oil-dispersible additive component in a minor amount of 0.01 to 5.0 mass %, based on the total mass % of the lubricating oil composition, obtainable by reacting: an aliphatic polyamine having at least two carbon atoms and at least two nitrogen atoms with at least one of the nitrogen atoms present in the form of a primary amine group and at least one of the remaining nitrogen atoms present in the form of a primary or secondary amine group, and an aliphatic hydrocarbyl mono acid or derivative thereof of formula I wherein R 1 represents a C 9 to C 29 aliphatic hydrocarbyl group and X represents -OH or a suitable leaving group in a compound of formula I, said reaction being conducted in a manner and under conditions sufficient to react at least one amine group of the aliphatic polyamine with the aliphatic hydrocarbyl mono acid or derivative thereof of formula I to form at least one amide and/or imidazoline group; and, an oil-soluble or oil dispersible additive component in a minor amount of 0.01 to 5.0 mass %, based on the total mass % of the lubricating oil composition, of a primary amide of formula R 6 C NH 2 wherein R 6 represents a C 9 to C 29 aliphatic hydrocarbyl group. an oil of lubricating viscosity in a major amount; an oil-soluble or oil-dispersible additive component in a minor amount of 0.01 to 5.0 mass %, based on the total mass % of the lubricating oil composition, obtainable by reacting: an aliphatic polyamine having at least two carbon atoms and at least two nitrogen atoms with at least one of the nitrogen atoms present in the form of a primary amine group and at least one of the remaining nitrogen atoms present in the form of a primary or secondary amine group, and an aliphatic hydrocarbyl mono acid or derivative thereof of formula I wherein R 1 represents a C 9 to C 29 aliphatic hydrocarbyl group and X represents -OH or a suitable leaving group in a compound of formula I, said reaction being conducted in a manner and under conditions sufficient to react at least one amine group of the aliphatic polyamine with the aliphatic hydrocarbyl mono acid or derivative thereof of formula I to form at least one amide and/or imidazoline group; and, an aliphatic polyamine having at least two carbon atoms and at least two nitrogen atoms with at least one of the nitrogen atoms present in the form of a primary amine group and at least one of the remaining nitrogen atoms present in the form of a primary or secondary amine group, and an aliphatic hydrocarbyl mono acid or derivative thereof of formula I wherein R 1 represents a C 9 to C 29 aliphatic hydrocarbyl group and X represents -OH or a suitable leaving group in a compound of formula I, said reaction being conducted in a manner and under conditions sufficient to react at least one amine group of the aliphatic polyamine with the aliphatic hydrocarbyl mono acid or derivative thereof of formula I to form at least one amide and/or imidazoline group; and, an oil-soluble or oil dispersible additive component in a minor amount of 0.01 to 5.0 mass %, based on the total mass % of the lubricating oil composition, of a primary amide of formula R 6 C NH 2 wherein R 6 represents a C 9 to C 29 aliphatic hydrocarbyl group.