Key Specifications
Cylinder-liner and piston-ring lubrication in slow-speed 2-stroke crosshead marine diesel engines, delivered by the engine's cylinder lubricators.
Technical Detail
Matching BN to fuel sulphur
The Base Number is chosen to neutralise the sulphuric acid formed during combustion. Since IMO 2020, vessels burning VLSFO (≤0.50% sulphur) typically use BN 25–40 cylinder oils, while scrubber-fitted ships on HSFO (up to 3.50% sulphur) run BN 70–100 and occasionally BN 140. Over-based oil on low-sulphur fuel can leave hard calcium deposits; under-based oil on high-sulphur fuel allows corrosive liner wear.
Feed rate and lubricators
Cylinder oil is metered by electronically controlled lubricators (MAN Alpha, Wärtsilä, Hans Jensen). Feed rate is tuned to load and fuel sulphur to strike the balance between adequate acid neutralisation and avoiding deposit build-up. Modern engines run feed rates around 0.6–1.2 g/kWh.
Cold corrosion and deposits
Low-load and low-sulphur operation can cause cold corrosion at the top of the liner where combustion gases condense. Correct BN selection, feed-rate management and periodic drain-oil / scrape-down analysis keep liner wear within engine-maker limits.
Ports Where We Supply Marine Cylinder Oil
Seven Ocean procures and delivers Marine Cylinder 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
How do I choose the right BN cylinder oil?
Match it to the sulphur content of the fuel you are burning. VLSFO (≤0.50%) generally calls for BN 25–40; HSFO on scrubber vessels calls for BN 70–100. Your engine maker's service letters give the exact recommendation for your unit.
Can one cylinder oil cover both VLSFO and HSFO?
Some mid-BN and dual-purpose oils exist, but running a single BN across widely different fuel sulphur is a compromise. Vessels switching between fuels often carry two grades and change feed accordingly.
Do you supply engine-maker approved grades?
Yes. We supply cylinder oils carrying MAN Energy Solutions and WinGD/Wärtsilä No-Objection Letters. Tell us the engine type and fuel and we'll match the approved grade.