Lubricating oils

A method of increasing the additive solubility or detergency of a lubricant composition which comprises adding to the lubricant composition:

• a) 5 wt % to 20 wt % based on the total weight of the composition of an amide, where the amide is a liquid at room temperature, has a pour point measured according to the method set out in ASTM D97 of not higher than −20° C. and is of Formula (Ia) or (Ib)
• wherein:
• R1 and R2 are independently selected from the group consisting of an isopropyl group and a C3 to C18 branched, saturated or unsaturated, primary hydrocarbyl group;
• R3 is selected from the group consisting of C3 to C23 linear or branched, saturated or unsaturated hydrocarbyl groups;
• R4 is selected from the group consisting of C1 to C12 linear or branched, saturated or unsaturated hydrocarbylene groups;
• and
• n is 0 or 1;
• and
• b) 0.5 wt % to 2 wt % based on the total weight of the composition of at least one additive that is a molybdenum dialkyldithiocarbamate,
• wherein the lubricant composition comprises 40 wt % to 95 wt % based on the total weight of the composition of a base oil comprising a lubricant component selected from API Groups IV, IV+ and mixtures of IV or IV+ with one or more of API Groups I, II, III, III+ and V, wherein for the mixtures, the Group IV or IV+ component is the majority component.

A method of producing a hydrolytically stable lubricant composition comprising:

• a) reacting a secondary, branched amine and a carboxylic acid to form an amide;
• and
• b) adding at least one additive that is a molybdenum dialkyldithiocarbamate to the amide,
• wherein the secondary, branched amine reactant has the formula (II):
• wherein R1 and R2 are independently selected from the group consisting of an isopropyl group, and a C3 to C18 branched, saturated or unsaturated, hydrocarbyl group, and
• wherein the amide is a liquid at room temperature, has a pour point measured according to the method set out in ASTM D97 of not higher than −20° C. and is of Formula (Ia) or (Ib):
• wherein:
• R1 and R2 are as defined;
• R3 is selected from the group consisting of C3 to C23 linear or branched, saturated or unsaturated hydrocarbyl groups;
• R4 is selected from the group consisting of C1 to C12 linear or branched, saturated or unsaturated hydrocarbylene groups;
• and
• n is 0 or 1, and
• wherein:
• the amide is present in the lubricant composition in an amount of 5 wt % to 20 wt % based on the total weight of the composition,
• the additive is present in the lubricant composition in an amount of 0.5 wt % to 2 wt % based on the total weight of the composition, and
• the lubricant composition comprises 40 wt % to 95 wt % based on the total weight of the composition of a base oil comprising a lubricant component selected from API Groups IV, IV+ and mixtures of IV or IV+ with one or more of API Groups I, II, III, III+ and V, wherein for the mixtures, the Group IV or IV+ component is the majority component.