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

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

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.