Extended operation engine coolant composition

1. An engine coolant composition comprising:

50% or more by weight of a glycol-based coolant liquid;

between about 0.1% by weight and about 10% by weight of a first carboxyl component selected from the group consisting of aliphatic dibasic acids or their salts having from 5 to 13 carbons, and mixtures thereof;

between about 0.01% by weight and about 10% by weight of isononanoic acid or a salt formed therefrom; and

at least one inorganic acid or its salt as a corrosion inhibitor, selected from the group consisting of molybdates, phosphates, and combinations thereof, wherein the composition excludes nitrous acid or the alkali metal, alkaline earth, or ammonium salts thereof; and the composition excludes silicates.

2. The composition of claim 1 wherein the isononanoic acid is present at a concentration between about 0.01% by weight and about 1% by weight.

3. The composition of claim 1 wherein the isononanoic acid is present at a concentration between about 0.10% by weight and about 1% by weight.

4. The composition of claim 1 wherein the isononanoic acid is present at a concentration between about 0.25% by weight and about 1% by weight.

5. The composition of claim 1 wherein the isononanoic acid is selected from the group consisting of 7-methyloctanoic acid, 6,6-dimethylheptanoic acid, 3,5,5-trimethylhexanoic acid, 3,4,5-trimethylhexanoic acid, 2,5,5-trimethylhexanoic acid, 2,2,4,4-tetramethylpentanoic acid, and combinations thereof.

6. The composition of claim 1 wherein greater than 90% of isononanoic acid is one of 7-methyloctanoic acid, 6,6-dimethylheptanoic acid, 3,5,5-trimethylhexanoic acid, 3,4,5-trimethylhexanoic acid, 2,5,5-trimethylhexanoic acid, and 2,2,4,4-tetramethylpentanoic acid.

7. The composition of claim 6 wherein greater than 95% of isononanoic acid is 3,5,5-trimethylhexanoic acid.

8. The composition of claim 1 further including an azole.

9. The composition of claim 1 wherein the first carboxyl component is adipic acid.

10. The composition of claim 1 wherein the first carboxyl component is sebacic acid.

11. The composition of claim 1 wherein the first carboxyl component is dodecanedioic acid.

12. The composition of claim 1 wherein the inorganic acid salt includes sodium molybdate.

13. The composition of claim 1 wherein the inorganic acid salt includes dipotassium phosphate.

14. A method for reducing pitting corrosion in an engine comprising incorporating into a coolant composition an amount of isononanoic acid, the salt thereof, or combinations of the acid and salt, effective to reduce pitting, and at least one inorganic acid or its salt as a corrosion inhibitor, selected from the group consisting of molybdates, phosphates, and combinations thereof in the absence of nitrous acid or the alkali metal, alkaline earth, or ammonium salts thereof, and in the absence of silicates.

15. An engine coolant composition comprising:

between about 85% by weight and about 95% by weight of a glycol-based coolant liquid;

between about 0.1% by weight and about 6% by weight of a first carboxyl component selected from the group consisting of aliphatic dibasic acids or the alkali metal, alkaline earth, or ammonium salts thereof having from 5 to 13 carbons, and mixtures thereof;

between about 0.01% by weight and 1% by weight of isononanoic acid or a salt formed therefrom; and

at least one inorganic acid or its salt as a corrosion inhibitor, selected from the group consisting of molybdates, phosphates, and combinations thereof, wherein the composition excludes nitrous acid or the alkali metal, alkaline earth, or ammonium salts thereof; and the composition excludes silicates.

16. The composition of claim 15 wherein the first carboxylic acid is present at a concentration between about 4% by weight and about 6% by weight.

17. The composition of claim 15 wherein the isononanoic acid is present at a concentration between about 0.25% by weight and about 1% by weight.

18. The composition of claim 15 wherein the isononanoic acid is selected from the group consisting of 7-methyloctanoic acid, 6,6-dimethylheptanoic acid, 3,5,5-trimethylhexanoic acid, 3,4,5-trimethylhexanoic acid, 2,5,5-trimethylhexanoic acid, 2,2,4,4-tetramethylpentanoic acid, and combinations thereof.

19. The composition of claim 15 wherein greater than 90% of isononanoic acid is one of 7-methyloctanoic acid, 6,6-dimethylheptanoic acid, 3,5,5-trimethylhexanoic acid, 3,4,5-trimethylhexanoic acid, 2,5,5-trimethylhexanoic acid, and 2,2,4,4-tetramethylpentanoic acid.

20. The composition of claim 19 wherein greater than 95% of isononanoic acid is 3,5,5-trimethylhexanoic acid.

21. The composition of claim 15 , further including an azole.

22. The composition of claim 15 wherein the first carboxyl component is adipic acid.

23. The composition of claim 15 wherein the first carboxyl component is sebacic acid.

24. The composition of claim 15 wherein the first carboxyl component is dodecanedioic acid.

25. The composition of claim 15 wherein the inorganic acid salt includes sodium molybdate.

26. The composition of claim 15 wherein the inorganic acid salt includes dipotassium phosphate.

27. A method of inhibiting corrosion in an iron containing

component of an engine coolant system comprising adding an amount of

isononanoic acid or a salt formed therefrom effective to reduce pitting in an engine

coolant composition; and

adding the engine coolant composition to an engine coolant system;

wherein the isononanoic acid in the engine coolant composition is sufficient to pass engine pitting test ASTM D 7583-09 in the absence of nitrous acid or the alkali metal, alkaline earth, or ammonium salts thereof; and in the absence of silicates.

28. The method of claim 14 further incorporating into the coolant composition a carboxyl component selected from the group consisting of aliphatic dibasic acids or their salts having from 5 to 13 carbons, and mixtures thereof.