Lubricating oil composition
The use, in the lubrication of a spark-ignited or compression-ignited internal combustion engine which is fuelled with a biofuel, of a minor amount of an oil-soluble or oil-dispersible additive component (B), as defined herein, in combination with a minor amount of an oil-soluble or oil-dispersible additive component (C), as defined herein, in a lubricating oil composition, to reduce and/or inhibit the corrosion of the metallic engine components, wherein the lubricating oil composition becomes contaminated with the biofuel during operation of the engine.
1. A lubricating oil composition comprising:
(A) an oil of lubricating viscosity in a major amount;
(B) an oil-soluble or oil-dispersible additive component in a minor amount, obtained by reacting:
(b1) 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
(b2) 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 (b1) with the aliphatic hydrocarbyl mono acid or derivative thereof (b2) of formula I to form at least one amide and/or imidazoline group; and,
(C) an oil-soluble or oil dispersible additive component in a minor amount comprising a primary amide of formula R 6 C(O)NH 2 wherein R 6 represents a C 9 to C 29 aliphatic hydrocarbyl group;
wherein the lubricating oil composition is contaminated with at least 0.3 mass %, based on the total mass of the lubricating oil composition, of a biofuel or a decomposition product thereof and mixtures thereof.
2. The lubricating oil composition as claimed in claim 1 , wherein the biofuel is an alcohol based fuel.
3. The lubricating oil composition as claimed in claim 2 , wherein the alcohol based fuel is an ethanol based fuel.
4. The lubricating oil composition as claimed claim 1 , wherein additive component (B) includes at least one primary or secondary amine group.
5. The lubricating oil composition as claimed in claim 1 , wherein the aliphatic polyamine (b1) is an aliphatic C 2 to C 20 hydrocarbyl polyamine wherein at least two of the nitrogen atoms are present in the form of a primary amine group.
6. The lubricating oil composition as claimed in claim 1 , wherein the aliphatic polyamine (b1) is a polyalkylene polyamine having at least 3 nitrogen atoms and 4 to 20 carbon atoms, wherein at least two of the nitrogen atoms are present in the form of a primary amine group and at least one of the remaining nitrogen atoms is present in the form of a secondary amine group.
7. The lubricating oil composition as claimed in claim 6 , wherein the polyalkylene polyamine which (b1) represents is a polyethylene polyamine.
8. The lubricating oil composition as claimed in claim 7 , wherein the polyethylene polyamine comprises tetraethylene pentamine.
9. The lubricating oil composition as claimed in claim 1 , wherein the aliphatic polyamine (b1) comprises a compound of formula II:
wherein: each R 2 independently represents at each occurrence hydrogen, C 1 to C 12 alkyl, C 2 to C 6 alkenyl or C 1 to C 12 alkyl amine; R 3 and R 4 each independently represent hydrogen, C 1 to C 12 alkyl, C 2 to C 6 alkenyl or C 1 to C 12 alkyl amine; a is an integer from 0 to 10; each n independently represents at each occurrence an integer from 2 to 6; with the proviso that when a is 0 then at least one of R 3 and R 4 represents hydrogen.
10. The lubricating oil composition as claimed in claim 1 , wherein R′ in the aliphatic hydrocarbyl mono acid or derivative thereof (b2) of formula I represents an acyclic C 9 to C 29 alkyl group.
11. The lubricating oil composition as claimed in claim 10 , wherein the acyclic C 9 to C 29 alkyl group which R′ represents in a compound of formula I is a branched chain acyclic C 9 to C 29 alkyl group.
12. The lubricating oil composition as claimed in claim 1 , wherein the aliphatic hydrocarbyl mono acid or derivative thereof (b2) of formula I comprises isostearic acid or a derivative thereof, stearic acid or a derivative thereof.
13. The lubricating oil composition as claimed in claim 1 , wherein R 6 in a compound of formula R 6 C(O)NH 2 which additive component (C) represents is an acyclic C 9 to C 29 alkenyl group having a single double bond.
14. The lubricating oil composition as claimed in claim 1 , wherein additive component (C) is oleamide.
15. A method of lubricating a spark-ignited or compression-ignited internal combustion engine which is fuelled with a biofuel, comprising operating the engine with a lubricating oil composition, comprising: (A) an oil of lubricating viscosity in a major amount; a minor amount of an oil-soluble or oil-dispersible additive component (B); and, a minor amount of an oil-soluble or oil-dispersible additive component (C), wherein said oil-soluble or oil-dispersible additive component (B) and said an oil-soluble or oil-dispersible additive component (C) are each as defined in accordance with claim 1 .