Government regulations limiting the content of undesirable compounds in diesel engine exhaust streams have been enacted by the major industrial nations. Engine design modifications have been required to satisfy these regulations. Future, more stringent requirements will require additional modification, and perhaps application of exhaust aftertreatment and/or alternative fuel approaches.
These design changes affect lubricant behavior and may impose a new set of requirements for satisfactory performance. The investigations reported here sought to identify the nature and magnitude of the need, particularly the positive and negative effects of lubricant variables on exhaust emissions themselves.
This work demonstrates that broad latitude exists to meet the needs of modified engines with chemical additive treatments. Maintenance of oil consumption rate is seen to be the primary emission-oriented function to expect of additive systems. The additive chemistry required to do this is itself inconsequential to measured emission rates.
Engines built for regulated markets, where specified fuels and lubricants are available, will also be sold to the unregulated markets, where they must operate with indigenous fuels and lubricants. Extension of the testing data indicates that fuel compositional factors dictate both the emission behavior and lubrication requirements of the engine.
In the case of aftertreated designs, strong potential is shown for chemical fuel supplements to provide autoregeneration of passive particulate collection systems.