Maintaining the quality of lubricating oil in main and auxiliary diesel engines is required to prevent engine breakdowns and ensure safe operation. Lubricating oil reduces friction, prevents corrosion, and acts as a cooling medium. Regular testing of the oil is essential to monitor its condition and identify potential problems, such as water contamination or a decrease in viscosity. Onboard testing can provide immediate analysis, while shore-based laboratories offer more detailed analysis, including future life and performance capability. Early detection and correction of issues can prevent costly repairs and downtime.

Methods adopted to maintain the quality of crankcase oil:

(i) Filtration system

The filtration system consists of 3 filters, as shown in the above figure:

• Suction filter with a magnet before the LO pump
• Auto backwash filter after LO cooler
• Bypass filter for auto backwash filter

(ii) Purification system:

• The purification system is shown in the above diagram
• The purifier is run sump to sump to separate water and impurities.
• It helps to maintain the quality of crankcase LO and also avoids the growth of microbes.

(iii) Shipboard LO test:

• LO test is carried out onboard to check the water content, TBN and viscosity of the oil
• This helps to constantly monitor the system and maintain the LO properties

(iv) Laboratory test:

• LO samples are sent for shore analysis to know the detailed condition of LO quality and actions or suggestions given to maintain the quality.

(v) Other methods adopted:

• Visual check of LO sump for discolouration, smell, impurities, etc
• Maintaining proper LO temperature
• Maintaining good LO cooler efficiency
• Keeping the combustion system in a good state.