A lubricant for a medical device includes an anti-friction material and a radical scavenger.

A lubricant composition includes a base oil, a phenothiazine-based polymerization inhibitor, and a polymerization inhibitory accelerator including a hindered phenol-based compound and a hydroquinone-based compound. A self-polymerization in a polymerizing process is suppressed by an interaction between the polymerization inhibitor and the polymerization inhibitory accelerator. A method of preparing a copolymer using the lubricant composition is also provided.

A lubricant composition includes a base oil, a phenothiazine-based polymerization inhibitor, and a polymerization inhibitory accelerator including a hindered phenol-based compound and a hydroquinone-based compound. A self-polymerization in a polymerizing process is suppressed by an interaction between the polymerization inhibitor and the polymerization inhibitory accelerator. A method of preparing a copolymer using the lubricant composition is also provided.

A lubricant composition is provided which comprises a base oil and hydroxytyrosol and/or esters thereof. Also provided is a lubricant composition in which the esters have a solubility in the base oil at 25 C. of at least 0.1 g/l. Further provided is a lubricant composition in which the esters are at least partly carboxylic acid esters comprising esters of hydroxytyrosol and C.sub.2-10 carboxylic acids.

A lubricant composition is provided which comprises a base oil and hydroxytyrosol and/or esters thereof. Also provided is a lubricant composition in which the esters have a solubility in the base oil at 25 C. of at least 0.1 g/l. Further provided is a lubricant composition in which the esters are at least partly carboxylic acid esters comprising esters of hydroxytyrosol and C.sub.2-10 carboxylic acids.

A lubricant composition includes a base oil, a phenothiazine-based polymerization inhibitor, and a polymerization inhibitory accelerator including a hindered phenol-based compound and a hydroquinone-based compound. A self-polymerization in a polymerizing process is suppressed by an interaction between the polymerization inhibitor and the polymerization inhibitory accelerator. A method of preparing a copolymer using the lubricant composition is also provided.

A lubricant composition includes a base oil, a phenothiazine-based polymerization inhibitor, and a polymerization inhibitory accelerator including a hindered phenol-based compound and a hydroquinone-based compound. A self-polymerization in a polymerizing process is suppressed by an interaction between the polymerization inhibitor and the polymerization inhibitory accelerator. A method of preparing a copolymer using the lubricant composition is also provided.

Lubricating oil composition is provided. The composition includes several components including a major amount of a base oil, a mixture of alkylated diphenylamines having a weight ratio of mono-alkylated diphenylamine to di-alkylated diphenylamine ranging from 0.6 to 4.0, and a molybdenum or sulfur additive that provides synergistic enhancement of oxidation stability in combination with the mixture of alkylated diphenylamines.

Lubricating oil composition is provided. The composition includes several components including a major amount of a base oil, a mixture of alkylated diphenylamines having a weight ratio of mono-alkylated diphenylamine to di-alkylated diphenylamine ranging from 0.6 to 4.0, and a molybdenum or sulfur additive that provides synergistic enhancement of oxidation stability in combination with the mixture of alkylated diphenylamines.

This disclosure provides a method for improving or maintaining antioxidant 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. The formulated oil has a composition including a lubricating oil base stock as a major component, and at least one functionalized quercetin antioxidant, as a minor component. The at least one functionalized quercetin antioxidant is soluble in the lubricating oil. Antioxidant performance is improved or maintained as compared to antioxidant performance achieved using a lubricating oil containing a phenolic or aminic antioxidant, as determined by Lubricant Oxidation Test as described herein or Catalytic Oxidation Test as described herein. This disclosure also relates to lubricating oils having at least one functionalized quercetin antioxidant. The lubricating oils are useful as passenger vehicle engine oils (PVEO), commercial vehicle engine oils (CVEO), and other mechanical industrial applications.