Abstract: A marine engine lubricating oil composition for a slow or medium speed diesel engine comprises a major amount of an oil of lubricating viscosity that contains a minor amount of a fuel oil with a residual fuel content and, admixed therewith, a minor amount of at least one oil-soluble or oil-dispersible ashless organic compound having at least two adjacent, substitutable carbon atoms being either part of an aromatic moiety or being connected by a double bond, each carrying an O— or O— and N-containing functional group, both groups being derived from a carboxy group.

Abstract: A marine engine lubricating oil composition for a slow or medium speed diesel engine comprises a major amount of an oil of lubricating viscosity that contains a minor amount of a fuel oil with a residual fuel content and, admixed therewith, a minor amount of at least one oil-soluble or oil-dispersible ashless organic compound having at least two adjacent, substitutable carbon atoms being either part of an aromatic moiety or being connected by a double bond, each carrying an O- or O- and N-containing functional group, both groups being derived from a carboxy group.