Lubricant composition for marine engine

1. A lubricant composition for 4-stroke or 2-stroke marine engine, comprising:

a) at least one lubricating base oil,

b) from 0.2 to 2% by weight of at least one olefin copolymer, wherein the olefin copolymer is a straight-chain copolymer of ethylene and propylene,

c) from 0.3 to 5% by weight of at least one copolymer of styrene and hydrogenated isoprene,

d) from 0.5 to 1.5% by weight of at least one glycerol ester, wherein the glycerol ester is a mixed ester of glycerol with at least one fatty acid having 8 to 24 carbon atoms and at least one carboxylic acid also comprising a hydroxyphenyl function, and

e) from 5 to 10% by weight of at least one detergent, based on the total weight of the lubricant composition.

2. The lubricant composition according to claim 1 wherein the hydrogenated styrene-isoprene copolymer has a quantity by weight of hydrogenated isoprene repeat units relative to the weight of the copolymer of between 50% and 95%.

3. The lubricant composition according to claim 1 wherein the detergents are chosen from among carboxylates, sulfonates and/or phenates, taken alone or in a mixture.

4. The lubricant composition according to claim 1 having a BN determined as per standard ASTM D-2896 of 5 to 100 mg KOH/g.

5. The lubricant composition according to claim 1 having a kinematic viscosity measured as per standard ASTM D7279 at 100° C. of between 5.6 and 26.1 cSt.

6. The lubricant composition according to claim 1 wherein the lubricant base oils are chosen from among the base oils of Group 1 or Group 2, taken alone or in a mixture.

7. The lubricant composition according to claim 1 further comprising an anti-wear additive including zinc dithiophosphate.

8. The use of a lubricant composition according to claim 1 for lubricating 4-stroke or 2-stroke marine engines.

9. The use of a lubricant composition according to claim 1 , wherein the composition reduces fuel consumption of 4-stroke or 2-stroke marine engines.

10. A method of using a lubricant composition, the method comprising:

using at least one glycerol ester, wherein the glycerol ester is a mixed ester of glycerol with at least one fatty acid having 8 to 24 carbon atoms and at least one carboxylic acid also comprising a hydroxyphenyl function and wherein the glycerol ester is from 0.5 to 1.5% by weight of the lubricant composition, of the lubricant composition in a 2-stroke or 4-stroke marine engine, the lubricant composition further comprising at least one lubricant base oil, from 0.2 to 2% by weight of at least one olefin copolymer wherein the olefin copolymer is a straight-chain copolymer of ethylene and propylene, from 0.3 to 5% by weight of at least one hydrogenated styrene-isoprene copolymer, and from 5 to 10% by weight of at least one detergent, based on the total weight of the lubricant composition; and

improving the engine or a crankcase cleanliness of the 4-stroke or 2-stroke marine engine.

11. A concentrate of additives comprising:

a) from 2 to 20% by weight of at least one olefin copolymer, wherein the olefin copolymer is a straight-chain copolymer of ethylene and propylene,

b) from 5 to 30% by weight of at least one copolymer of styrene and hydrogenated isoprene,

c) from 0.5 to 10% by weight of at least one glycerol ester, wherein the glycerol ester is a mixed ester of glycerol with a least one fatty acid having 8 to 24 carbon atoms and at least one carboxylic acid also comprising a hydroxyphenyl function, and

d) from 10 to 70% by weight of at least one detergent, based on the total weight of the concentrate of additives,

wherein the concentrate of additives is a 4× to 5× concentrate for dilution in a base oil or in a mixture of base oils.

12. The lubricant composition according to claim 1 wherein the detergents are chosen from among calcium carboxylates, calcium sulfonates and/or calcium phenates, taken alone or in a mixture.

13. The lubricant composition according to claim 1 having a BN determined as per standard ASTM D-2896 of 7 to 80 mg KOH/g.

14. The lubricant composition according to claim 1 having a BN determined as per standard ASTM D-2896 of 10 to 60 mg KOH/g.

15. The lubricant composition according to claim 1 having a kinematic viscosity measured as per standard ASTM D7279 at 100° C. of between 9.3 and 21.9 cSt.

16. The lubricant composition according to claim 1 having a kinematic viscosity measured as per standard ASTM D7279 at 100° C. of between 12.5 and 16.3 cSt.

17. A lubricant composition for 4-stroke or 2-stroke marine engine comprising:

51% by weight of a Group 1 base oil called Neutral Solvent 150NS of viscosity at 40° C. of 30 cSt;

27.3% by weight of a Group 1 base oil called Neutral Solvent 330NS of viscosity at 40° C. of 66 cSt;

2.5% by weight of a straight-chain olefin copolymer comprising 50 weight % of ethylene repeat units and having a weight average molecular weight Mw of 171 700, a number average molecular weight Mn of 91 120, a polydispersity index of 1.9, the olefin copolymer being diluted to 12.5 weight % in a Group 1 base oil;

5% by weight of a star-branched copolymer of styrene and hydrogenated isoprene, comprising 90 weight % of hydrogenated isoprene repeat units and 10 weight % styrene repeat units, and having a weight average molecular weight Mw of 605 000, a number average molecular weight Mn of 439 500, a polydispersity index of 1.4, the copolymer being diluted to 10.7 weight % in a Group 1 base oil;

1% by weight of a mixed ester of glycerol and C8-C18 fatty acids, and 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid, the mixed ester being diluted to 80 weight % in an aliphatic cycloparaffinic hydrocarbon;

12.7% by weight of detergents containing calcium carboxylates, calcium sulfonates and calcium phenates, the packet being diluted to 50 weight % in a Group 1 base oil.

18. The lubricant composition according to claim 1 wherein the quantity of the olefin copolymer ranges from 0.2 to 0.5% by weight, based on the total weight of the lubricant composition.

19. The lubricant composition according to claim 1 wherein the quantity of the glycerol ester ranges from 0.5 to 1% by weight, based on the total weight of the lubricant composition.

20. The lubricant composition according to claim 1 wherein the quantity of the olefin copolymer ranges from 0.2 to 0.5% by weight and the quantity of the glycerol ester ranges from 0.5 to 1% by weight, based on the total weight of the lubricant composition.