Diesel engines are more complex and require more maintenance, but they also deliver superior performance, economical fuel consumption, low emission and higher reliability.

An unscheduled repair is no longer merely an inconvenience, it is now a financial liability. This emergence of downtime as a financial risk has required a change from the “Maintenance Base Condition" where the maintenance is carried out when fail occure an engine, to become the "Preventive Maintenance" where the maintenance is carried out to avoid failure with schedule maintenance.

Preventive maintenance can be divided into the following level :

• Level 1  :  Daily maintenance and routine maintenance.
• Level 2  :  Top overhaul or middle overhaul.
• Level 3  :  General overhaul.