Key Specifications
Crankcase, crosshead-bearing, guide-shoe and camshaft lubrication in slow-speed 2-stroke crosshead engines, held as a circulating charge in the sump.
Technical Detail
A circulating charge, not a total-loss oil
Where cylinder oil is consumed, system oil circulates and is reused. It is continuously cleaned by the engine's centrifugal separators. The oil must resist oxidation, carry loads on the bearings and guides, and hold up over thousands of running hours.
Water contamination and purification
The main threats are water ingress (from stuffing-box leakage or cooler faults) and contamination by cylinder-oil drain-down. Good demulsibility lets the purifier remove water cleanly; strong detergency keeps combustion by-products in suspension until they are separated out.
Load carrying and cleanliness
The crosshead bearing is one of the most heavily loaded plain bearings in any engine. System oil must maintain film strength under high specific load while keeping running gear and the sump clean. Routine oil analysis tracks water, BN retention, viscosity and wear metals.
Ports Where We Supply Marine System Oil
Seven Ocean procures and delivers Marine System Oil alongside bunker fuel at every major bunkering hub worldwide and across all 25 Indian ports — matched to your engine maker's approvals. Select a port for its full bunkering guide.
International Hubs
Indian Ports
Frequently Asked Questions
What is the difference between system oil and cylinder oil?
Cylinder oil is a total-loss lubricant injected onto the liner and consumed; system oil is a low-BN circulating oil that lubricates the crankcase and running gear and stays in service. They are not interchangeable.
Why is the BN so low compared with cylinder oil?
System oil does not contact the acidic combustion zone, so it needs little acid-neutralising reserve. A modest BN with strong detergency and demulsibility is what the crankcase requires.
How often should system oil be analysed?
Most operators sample every 1–3 months, tracking water content, viscosity, BN and wear metals. We can arrange grades and a testing programme together with the supply.