Piston - ring - liner combinations have been identified that will reduce oil consumptions to less than 1/4 of the consumption for small-bore diesel engines as received. This is based on 31 test series from 1966 to date wherein a factorial plan has been used. In the 31 series some of the potential factors have been studied many times and the resulting data have been compiled into a group of summary tables and these tables are presented. Some factors are specific to each engine and some are general to all engines. The need to have proper pistons and proper liners to make piston rings work are discussed.