Provided is a lubricating oil composition and methods for controlling one or more of foam tendency and foam stability in such composition using as the oil a mixture of at least two base stocks. The at least two base stocks have a surface tension difference between them such that, when the surface tension difference is greater than 1.0 dynes/cm, then one or more of foam tendency and foam stability are enhanced as compared to foam tendency and foam stability achieved using the base stocks separately and not in the mixture. When the surface tension difference between them is less than 1.0 dynes/cm, then one or more of foam tendency and foam stability are reduced or equivalent as compared to foam tendency and foam stability achieved using the base stocks separately and not in the mixture. Two low-foaming base stocks can produce a significant high foam response that reduces or eliminates the need for pro-foaming additives.

A method for improving filterability, while maintaining or improving antifoaming performance, of a lubricating oil in an engine or other mechanical component lubricated with the lubricating oil by using as the lubricating oil a formulated oil. A method for improving antifoaming performance, while maintaining or improving filterability, of a lubricating oil in an engine or other mechanical component lubricated with the lubricating oil by using as the lubricating oil a formulated oil. The formulated oil has a composition including a lubricating oil base stock as a major component, and at least one antifoam agent, as a minor component. A lubricating oil having a composition including a lubricating oil base stock as a major component, and at least one antifoam agent, as a minor component. The antifoam agent is a silicone composition having a highly branched functionalized silicone backbone. The lubricating oils are useful as automotive gear lubricating compositions.

A method and system for lubricating at least one moving part with a lubricating medium includes a chamber configured to house at least one moving part, a lubricant reservoir configured to house a liquid lubricant, a gas reservoir configured to house a gas, and a controller configured to supply a first amount of the gas in the form of bubbles to a second amount of the liquid lubricant to entrain the bubbles of gas in the liquid lubricant. The controller is also configured to regulate proportions of the liquid lubricant and the gas as a function of at least one operating condition, including at least one of pressure, temperature, and flow rate, a solubility relationship between the liquid lubricant and the gas, and a size of the bubbles of gas, and supply the liquid lubricant with entrained bubbles of gas to at least one moving part.

A method for improving filterability, while maintaining or improving antifoaming performance, of a lubricating oil in an engine or other mechanical component lubricated with the lubricating oil by using as the lubricating oil a formulated oil. A method for improving antifoaming performance, while maintaining or improving filterability, of a lubricating oil in an engine or other mechanical component lubricated with the lubricating oil by using as the lubricating oil a formulated oil. The formulated oil has a composition including a lubricating oil base stock as a major component, and at least one antifoam agent, as a minor component. A lubricating oil having a composition including a lubricating oil base stock as a major component, and at least one antifoam agent, as a minor component. The antifoam agent is a silicone composition having a highly branched functionalized silicone backbone. The lubricating oils are useful as automotive gear lubricating compositions.

Defoaming agents comprising a silicone oil and silica particulates, lubricating oil compositions comprising the defoaming agent, methods of lubrication using a lubricating oil composition comprising the defoaming agent, and methods of reducing the foaming tendency/stability and/or improving the air release rates of non-aqueous fluids, such as lubricant oils, are provided.