The test kit “LUBE OIL CHECK 5” is designed for regular on-board monitoring of 5 crucial parameters of engine lube oil: water in oil, base number (BN), oil viscosity, salt water and soot contamination. Routine in-service oil analysis can help to early detect any off-specification issues (ongoing degradation of the oil quality, abnormal wear) and changes in the oil condition (oil contamination) before an actual problem occurs, thereby improving the engine system maintenance planning.