A lubricating oil composition comprises a major amount of an oil of lubricating viscosity and a minor amount of an unsymmetrical bis-succinimide, or a mixture of unsymmetrical bis-succinimides, of the structure (I): ##STR00001##
wherein one of R.sub.1 and R.sub.2 is a polyisobutylene group having a weight average molecular weight of 400 to 5,000, as determined by GPC with reference to linear polystyrene standards, and the other of R.sub.1 and R.sub.2 is a hydrocarbon group made by the metallocene-catalysed polymerisation of an -olefin feedstock; and x is from 1 to 10 and is the same for all molecules of structure (I), or an average of all molecules of structure (I) in a mixture of molecules of structure (I).

One or more fatty amines are soluble in a lubricating composition for preventing and/or reducing the metal losses of the parts of an engine, such as a marine engine. The parts are brought into contact with the lubricating composition in order to prevent or reduce the metal losses.

One or more fatty amines are soluble in a lubricating composition for preventing and/or reducing the metal losses of the parts of an engine, such as a marine engine. The parts are brought into contact with the lubricating composition in order to prevent or reduce the metal losses.

An oleaginous nanoparticle dispersion of nanoparticles having a core of an organic base material immobilized within a surfactant layer, the use thereof as a low ash, or ash-free source of TBN in lubricating oil compositions, and lubricating oil compositions formulated with such oleaginous nanoparticle dispersions.

An oleaginous nanoparticle dispersion of nanoparticles having a core of an organic base material immobilized within a surfactant layer, the use thereof as a low ash, or ash-free source of TBN in lubricating oil compositions, and lubricating oil compositions formulated with such oleaginous nanoparticle dispersions.

A lubricating oil composition comprises a major amount of an oil of lubricating viscosity and a minor amount of an unsymmetrical bis-succinimide, or a mixture of unsymmetrical bis-succinimides, of the structure (I):

##STR00001##

wherein one of R.sub.1 and R.sub.2 is a polyisobutylene group having a weight average molecular weight of 400 to 5,000, as determined by GPC with reference to linear polystyrene standards, and the other of R.sub.1 and R.sub.2 is a hydrocarbon group made by the metallocene-catalysed polymerisation of an -olefin feedstock; and x is from 1 to 10 and is the same for all molecules of structure (I), or an average of all molecules of structure (I) in a mixture of molecules of structure (I).

A lubricating oil composition comprises a major amount of an oil of lubricating viscosity and a minor amount of an unsymmetrical bis-succinimide, or a mixture of unsymmetrical bis-succinimides, of the structure (I):

##STR00001##

wherein one of R.sub.1 and R.sub.2 is a polyisobutylene group having a weight average molecular weight of 400 to 5,000, as determined by GPC with reference to linear polystyrene standards, and the other of R.sub.1 and R.sub.2 is a hydrocarbon group made by the metallocene-catalysed polymerisation of an -olefin feedstock; and x is from 1 to 10 and is the same for all molecules of structure (I), or an average of all molecules of structure (I) in a mixture of molecules of structure (I).

A method for controlling formation and dissipation of at least one oligomeric or polymeric aminic antioxidant in a lubricating oil, during operation of 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 oligomeric or polymeric aminic antioxidant, as a minor component. The at least one oligomeric or polymeric aminic antioxidant is formed over time in situ from at least one monomeric aminic antioxidant during operation of the engine or other mechanical component. The at least one oligomeric or polymeric aminic antioxidant is dissipated over time in the lubricating oil during operation of the engine or other mechanical component. The at least one monomeric aminic antioxidant is present in an amount from greater than 2 to 10 wt. % of the lubricating oil.

A method for controlling formation and dissipation of at least one oligomeric or polymeric aminic antioxidant in a lubricating oil, during operation of 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 oligomeric or polymeric aminic antioxidant, as a minor component. The at least one oligomeric or polymeric aminic antioxidant is formed over time in situ from at least one monomeric aminic antioxidant during operation of the engine or other mechanical component. The at least one oligomeric or polymeric aminic antioxidant is dissipated over time in the lubricating oil during operation of the engine or other mechanical component. The at least one monomeric aminic antioxidant is present in an amount from greater than 2 to 10 wt. % of the lubricating oil.

Relating to the field of lubricant, more particularly relates to lubricant for marine engine, notably for a two-stroke marine engine. More particularly, relates to a lubricant for a marine engine including at least one lubricant base oil and at least one fatty amine.