Search Results

Global Heavy Duty Diesel engine emission legislation requires stepwise reduction of NOx and particulate emissions between 1989 and 2009. Today, most US diesel engine manufacturers are incorporating cooled Exhaust Gas Recirculation (EGR) and retarded engine timing as a means of reducing NOx emission. This has resulted in higher levels of soot being present in used oils. The first part of this paper builds on previous work with fresh oils and describes a study of the effect of highly sooted oils on low temperature pumpability in diesel engines. Experimental SAE 15W-40 Heavy Duty Diesel Oils (HDDO), formulated with different Viscosity Index Improver (VII) chemistries, were run in a Mack T-8 engine to obtain a soot level of approximately 6.5%. These sooted oils were then evaluated in a Cummins M11 engine installed in a low temperature chamber. Times to lubricate critical engine components were measured at temperatures ranging between -10 °C and -20 °C.

Changing diesel engine emission requirements for 2002 have led many diesel engine manufacturers to incorporate cooled Exhaust Gas Recirculation, EGR, as a means of reducing NOx. This has resulted in higher levels of soot being present in used oils. This paper builds on earlier work with fresh oils and describes a study of the effect of highly sooted oils on the low temperature pumpability in diesel engines. Four experimental diesel engine oils, of varying MRV TP-1 viscosities, were run in a Mack T-8 engine to obtain a soot level ranging between 6.1 and 6.6%. These sooted oils were then run in a Cummins M11 engine installed in a low temperature cell. Times to lubricate critical engine components were measured at temperatures ranging between -10 °C and -25 °C. A clear correlation was established between the MRV TP-1 viscosity of a sooted oil and the time needed to lubricate critical engine components at a given test temperature.

A 1995, 276kW (370 BHP) diesel engine was instrumented to provide measurements of temperature and oil pressure in five critical engine areas: the oil filter, the main gallery, the rocker shaft, the cam roller follower and the turbocharger. In addition, oil flow measurements were completed at the turbocharger. Using a proprietary test procedure, four different commercial SAE 15W-40 formulations were evaluated at -15 °C. Significant differences were observed between the test lubricants in terms of flow rate and time for establishing pressure in critical areas of the engine. In addition, with one oil, as a result of the high pressure drop in the filter, the bypass valve stayed open for several minutes, leaving unfiltered oil circulating in the engine. Our findings show that the MRV TP-1 viscosity at -20 °C or -25 °C is not capable of predicting all aspects of pumping performance of lubricants in a modern heavy duty engine.