An Overview of the Types, Characteristics, and Additive Selection of Marine Lubricating Oils

Marine lubricants include cylinder oil, system oil, and medium-speed tubular marine oil. They are designed to meet the demands of marine vessels that operate in extreme conditions.

 

Marine lubricants include cylinder oil, system oil, and medium-speed tubular marine oil. They are designed to meet the demands of marine vessels that operate in extreme conditions. 

 

1. Marine System Oil

• Application: Used for lubricating the crankcase of large crosshead low-speed diesel engines.
• Characteristics:
  • Strong Demulsibility: Easily separates from water.
  • Good Oxidation Stability: Resistant to oxidation at high temperatures.
  • Cleanliness and Dispersibility: Prevents the formation of deposits.
  • Acid Neutralization and Corrosion Resistance: Protects non-ferrous metals and bearing alloys.

 

 

Appropriate Viscosity and Viscosity Index: Kinematic viscosity at 100℃ is 11-14M㎡/S, viscosity index >90.

 

• Additives:
  • Cleanliness and Dispersibility Agent: Prevents deposit formation.
  • Antioxidant: Prevents oil oxidation at high temperatures.
  • Demulsifying Agent: Ensures separation from water.
  • Rust Inhibitor: Protects non-ferrous metals and bearing alloys.

 

2. Medium-Speed Tubular Marine Oil

 

• Application: Used for lubricating medium-speed tubular piston diesel engines.
• Characteristics:
  • High Load-Carrying Capacity: Reduces wear under boundary lubrication conditions.
  • Excellent Thermal Oxidation Stability: Minimizes the formation of lacquer, carbon, and sludge.
  • Moderate Total Base Number: Neutralizes acidic substances to prevent corrosion.
  • Good Cleanliness and Dispersibility: Maintains performance during centrifugal purification.

Good Water Resistance: Despite high-alkaline additives, maintains water resistance. 

• Additives:
  • Cleanliness and Dispersibility Agent: Prevents deposit formation, especially during centrifugal purification.
  • Antioxidant: Reduces lacquer, carbon, and sludge formation at high temperatures.
  • TBN Booster: Neutralizes acidic substances.
  • Anti-Wear Agent: Reduces wear.
  • Water Resistance Agent: Ensures performance in water-exposed conditions.

 

3. Cylinder Oil

 

• Application: Used for lubricating the piston and cylinder liner of large crosshead low-speed diesel engines.
• Characteristics:
  • Excellent Cleanliness and Dispersibility: Prevents carbon buildup in piston ring grooves and cylinder liner air ports.
  • Good Wear Resistance: Reduces sliding friction between piston rings and cylinder liner.
  • Strong Storage Stability: High additive content ensures stability.
• Additives:
  • Cleanliness and Dispersibility Agent: Prevents carbon buildup in piston ring grooves and cylinder liner air ports.
  • Anti-Wear Agent: Reduces sliding friction between piston rings and cylinder liner.
  • TBN Booster: Ensures storage stability.
  • Antioxidant: Although requirements are slightly lower, still necessary for harsh conditions.

Differences Among Them

• Lubrication Parts:
  • Marine System Oil: Lubricates, cools, and protects the crankcase.
  • Medium-Speed Tubular Marine Oil: Lubricates piston/cylinder parts and internal crankcase components.
  • Cylinder Oil: Lubricates the piston and cylinder liner.
• Working Conditions:
  • Marine System Oil: Does not come into direct contact with high-temperature exhaust gases, relatively mild conditions.
  • Medium-Speed Tubular Marine Oil: Direct contact with high-temperature pistons, cylinder liners, and exhaust gases from inferior fuels.
  • Cylinder Oil: Harsh conditions, high temperature and pressure.
• Performance Requirements:
  • Marine System Oil: Emphasizes demulsibility, oxidation stability, cleanliness, acid neutralization, and corrosion resistance.
  • Medium-Speed Tubular Marine Oil: Focuses on load-carrying capacity, thermal oxidation stability, cleanliness, and water resistance.
  • Cylinder Oil: Stresses cleanliness, wear resistance, and storage stability.

Additive Types

• Cleanliness and Dispersibility Agent: Prevents deposit formation.
• Antioxidant: Prevents oil oxidation at high temperatures.
• TBN Booster: Neutralizes acidic substances to prevent corrosion.
• Anti-Wear Agent: Reduces wear.
• Water Resistance Agent: Ensures performance in water-exposed conditions.
• Rust Inhibitor: Protects non-ferrous metals and bearing alloys.