The paper discusses the design and development of indirect injection diesel engines with particular reference to their production of combustion soot and to the crankcase lubricating oils ability to handle it. Bench and field test results obtained from Perkins 4.108 engines are presented on the performance of bearings, camshaft/tappets and lubricants. These results show that no wear problem exists, that the dispersancy of lubricants can be effectively assessed and that there is a potential for an improvement in oil drain periods by the use of synthetic oils. Results also show that for one lubricant unacceptable bearing corrosion was obtained. This was disturbing since the lubricant was qualified to both MIL-L-46152 and 2104C performance levels.
