Lubrication and lubricating oil compositions

1. A crankcase lubricating oil composition comprising, or made by admixing, an oil of lubricating viscosity, in a major amount, and, one or more N,N′-tetra-aliphatic hydrocarbyl phenylenediamines, in minor amounts, wherein one or two of said hydrocarbyl groups are branched at an alpha carbon atoms and have 3 to 12 carbon atoms and one or two of said hydrocarbyl groups are branched at a beta carbon atom and have 4 to 12 carbon atoms; any other alkyl group having 1 to 12 carbon atoms.

2. A composition, as claimed in claim 1 , wherein said hydrocarbyl groups are alkyl groups.

3. A composition, as claimed in claim 1 having a TBN measured according to ASTM D4739 of at least 6 mg KOH/g.

4. A composition, as claimed in claim 3 having a TBN measured according to ASTM D4739 of from about 6 to about 20 mg KOH/g.

5. A composition, as claimed in claim 1 , having a SASH content of no greater than 0.8 mass %.

6. A composition, as claimed in claim 1 , wherein at least 10% of the compositional TBN, as measured by ASTM D4739, is derived from said phenylenediamine compounds, and less than 25% of the compositional TBN is derived from ashless TBN sources other than said phenylenediamine compounds.

7. A composition, as claimed in claim 6 , wherein at least such as at least 15% of the compositional TBN, as measured by ASTM D4739, is derived from said phenylenediamine compounds.

8. A composition, as claimed in claim 7 , wherein at least 25% of the compositional TBN, as measured by ASTM D4739, is derived from said phenylenediamine compounds.

9. A composition, as claimed in claim 6 , wherein less than 20% of the compositional TBN is derived from ashless TBN sources other than said phenylenediamine compounds.

10. A composition, as claimed in claim 6 , wherein at least 25% of the compositional TBN, as measured by ASTM D4739, is derived from said phenylenediamine compounds, and less than 20% of the compositional TBN is derived from ashless TBN sources other than said phenylenediamine compounds.

11. A composition, as claimed in claim 1 , which is a crankcase lubricant for a heavy duty diesel (HDD) engine.

12. A composition, as claimed in claim 1 , which has copper corrosion performance in the high-temperature bench corrosion test (ASTM D6594) that falls within the limits of the API CJ-4 and ACEA E6 specification, and has fluoroelastomeric engine seal materials compatibility performance in the MB-AK6 test that falls within the limits of the MB p228.51 specification.

13. A concentrate for the preparation of a lubricating oil composition, as claimed in claim 1 , comprising from about 1 to about 30 mass % of one or more of said phenylenediamine compounds; from about 10 to about 40 mass % of a nitrogen-containing dispersant; from about 2 to about 20 mass % of at least one compound selected from an aminic antioxidant, a phenolic antioxidant, and a molybdenum compound; from about 5 to about 40 mass % of a detergent; and from about 2 to 20 mass % of a metal dihydrocarbyl dithiophosphate.

14. A method of lubricating surfaces of a compression-ignited internal combustion engine during its operation comprising:

(a) providing, in a minor amount, one or more N,N′-tetra-aliphatic hydrocarbyl phenylenediamines as defined in claim 1 in a major amount of an oil of lubricating viscosity to make a lubricating oil composition, the TBN of which, as measured by ASTM D4739 is thereby enhanced without concurrently increasing the SASH, and that has copper corrosion performance in the high-temperature bench corrosion test (ASTM D6594) that falls within the limits of the API CJ-4 and ACEA E6 specification, and has fluoroelastomeric engine seal materials compatibility performance in the MB-AK6 test that falls within the limits of the MB p228.51 specification;

(b) providing the lubricating oil composition to the engine crankcase; and

(c) operating said engine.

15. N,N′-tetra-aliphatic hydrocarbyl phenylenediamine of the formula:

wherein each of R 1 , R 2 , R 3 and R 4 is independently an aliphatic hydrocarbyl group, having 3 to 12 carbon atoms, at least one of R 1 , R 2 , R 3 and R 4 being a hydrocarbyl group branched in the position alpha to the attached nitrogen and having 3 to 12 carbon atoms, and at least one of R 1 , R 2 , R 3 and R 4 being a hydrocarbyl group branched in the position beta to the attached nitrogen, having 4 to 12 carbon atoms; R 5 , or each R 5 , is independently hydrogen or an aliphatic hydrocarbyl group, having 1 to 12 carbon atoms; and n is from 0 to 4.

16. Phenylenediamine, as claimed in claim 15 , wherein the hydrocarbyl group of one or more of R 1 , R 2 , R 3 and R 4 , and R 5 , when R 5 is a hydrocarbyl group, is an alkyl group.

17. Phenylenediamine, as claimed in claim 16 , wherein the hydrocarbyl group of each of R 1 , R 2 , R 3 and R 4 , and R 5 , when R 5 is a hydrocarbyl group, is an alkyl group.

18. Phenylenediamine, as claimed in claim 15 , wherein each of R 1 and R 3 is independently an alkyl group branched in the position alpha to the attached nitrogen atom, having 3 to 12 carbon atoms; and each of R 2 and R 4 is independently an alkyl group branched in the position beta to the attached nitrogen atom, having 4 to 12 carbon atoms.

19. Phenylenediamine, as claimed in claim 15 , having an average molecular weight of from about 450 to about 700.

20. Phenylenediamine, as claimed in claim 19 , having an average molecular weight of from about 450 to about 650.

21. Phenylenediamine, as claimed in claim 20 , having an average molecular weight of from about 500 to about 600.

22. Phenylenediamine as claimed in claim 15 , wherein the nitrogen atoms are arranged para to one another.

23. N,N′-di-(s-butyl)-N,N′-di-(2-ethylhexyl)-p-phenylenediamine.

24. N,N′-di(1,3-methylbutyl)-N,N′-di(2-ethylhexyl)-p-phenylenediamine.

25. Phenylenediamine, as claimed in claim 15 , having a TBN, measured as in ASTM D4739, of at least 50 mg KOH/g.

26. Phenylenediamine, as claimed in claim 25 , having a TBN, measured as in ASTM D4739, of at least 120 mg KOH/g.

27. A mixture of phenylenediamine compounds as claimed in claim 15 .