Lubricating Composition Containing an Antiwear Agent

1 . A lubricating composition comprising

(a) an oil of lubricating viscosity,

(b) 0.01 wt % to 5 wt % of a phosphite having at least one hydrocarbyl group that has 4 or more carbon atoms, wherein the phosphite having at least one hydrocarbyl group with 4 or more is represented by the formula:

wherein at least one of R 3 , R 4 and R 5 is a hydrocarbyl group containing at least 4 carbon atoms and the other may be hydrogen or a hydrocarbyl group, and wherein the phosphite has at least one hydrocarbyl group with 12 to 22 carbon atoms, and

(c) 0.01 wt % to 5 wt % of a compound derived from a hydroxy-carboxylic acid, wherein the compound derived from a hydroxy-carboxylic acid is represented by the formula:

wherein

n and m are independently integers of 1 to 5;

X is an aliphatic or alicyclic group, or an aliphatic or alicyclic group containing an oxygen atom in the carbon chain, or a substituted group of the foregoing types, said group containing up to 6 carbon atoms and having n+m available points of attachment;

each Y is independently —O—, >NH, or >NR 1 or two Ys together representing the nitrogen of an imide structure R—N< formed between two carbonyl groups; and

each R and R 1 is independently hydrogen or a hydrocarbyl group, provided that at least one R or R 1 group is a hydrocarbyl group; each R 2 is independently hydrogen, a hydrocarbyl group or an acyl group, further provided that at least one —OR 2 group is located on a carbon atom within X that is α or β to at least one of the —C(O)—Y—R groups, and wherein n=2 and m=1, or n and m both equal 2, or n=3 and n=1, or n=2 and m=0.

2 . The lubricating composition of claim 1 , wherein n and m both equal 2.

3 - 18 . (canceled)

19 . The lubricating composition of claim 1 , wherein the compound derived from the hydroxy-carboxylic acid is present at 0.1 wt % to 3 wt % of the lubricating composition.

20 . The lubricating composition of claim 1 , wherein the compound derived from the hydroxy-carboxylic acid is present at 0.5 wt % to 1 wt % of the lubricating composition

21 . The lubricating composition of claim 1 , wherein both R 3 and R 4 are hydrocarbyl groups.

22 . The lubricating composition of claim 1 , wherein the phosphite has at least one hydrocarbyl group with 14 to 20 carbon atoms.

23 . The lubricating composition of claim 1 , wherein the phosphite has at least one hydrocarbyl group with 16 to 18 carbon atoms.

24 . The lubricating composition of claim 1 , wherein the phosphite having at least one hydrocarbyl group with 4 or more carbon atoms is present at 0.1 wt % to 3 wt %, of the lubricating composition.

25 . The lubricating composition of claim 1 , wherein the phosphite having at least one hydrocarbyl group with 4 or more carbon atoms is present at 0.5 wt % to 1 wt % of the lubricating composition.

26 . The lubricating composition of claim 1 , wherein the phosphite having at least one hydrocarbyl group with 4 or more carbon atoms and the compound derived from the hydroxy-carboxylic acid are both present in an amount in the range of 0.1 wt % to 3 wt % and 0.1 wt % to 3 wt % respectively of the lubricating composition.

27 . The lubricating composition of claim 1 , wherein the phosphite having at least one hydrocarbyl group with 4 or more carbon atoms and the compound derived from the hydroxy-carboxylic acid are both present in an amount in the range of 0.5 wt % to 1 wt % and 0.5 wt % to 1 wt % respectively of the lubricating composition.

28 . The lubricating composition of claim 1 further comprising a zinc dialkyldithiophosphate, or mixtures thereof, wherein the zinc dialkyldithiophosphate is present at 0.75 wt % to 1.5 wt % of the lubricating composition.

29 . The lubricating composition of claim 1 , wherein the lubricating composition is characterised as having (i) a sulphur content of 0.5 wt % or less, (ii) a phosphorus content of 0.1 wt % or less, and (iii) a sulphated ash content of 1.5 wt % or less.

30 . The lubricating composition of claim 1 further comprising at least one of an antiwear agent, a dispersant viscosity modifier, a friction modifier, a viscosity modifier, an antioxidant, an overbased detergent, or mixtures thereof.

31 . The lubricating composition of claim 1 further comprising an overbased detergent, wherein the overbased detergent is selected from the group consisting of phenates, sulphur containing phenates, sulphonates, salixarates, salicylates, and mixtures thereof.

32 . A method of lubricating an internal combustion engine comprising supplying to the internal combustion engine the lubricating composition of claim 1 .

33 . The method of claim 32 , wherein the internal combustion engine has surfaces of an aluminium alloy, or aluminium composite.

34 . The method of claim 33 , wherein the aluminium alloy is a eutectic or hyper-eutectic aluminium alloy.

35 . The method of claim 34 , wherein the aluminium alloy is derived from an aluminium silicate.

36 . The method of claim 32 , wherein the internal combustion engine has surfaces of steel.