Marine Trunk Piston Engine Oils (TPEO) — 4-Stroke Engine Lubricants

Key Specifications

Technical Detail

One oil for cylinders and crankcase

Because the trunk piston runs directly in the cylinder and connects to the crankshaft, the same oil lubricates the combustion side and the bearings. TPEO therefore needs both acid-neutralising reserve for the cylinders and oxidation stability plus detergency for the crankcase.

Selecting BN by fuel

Distillate-burning gensets (MGO/MDO) typically use BN 12–30 TPEO; medium-speed engines on residual fuel (HFO/VLSFO) use BN 40–55 to handle the higher sulphur and combustion residue. Matching BN to fuel avoids both corrosive wear and deposit formation.

Soot and dispersancy

Medium-speed engines generate soot that the oil must keep dispersed to prevent filter blocking, ring sticking and bearing lacquer. High dispersancy and thermal stability protect performance across long drain intervals; oil analysis governs the actual change point.

Ports Where We Supply Marine TPEO

Seven Ocean procures and delivers Marine TPEO 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 does 'trunk piston' mean?

It describes a 4-stroke engine where the piston is directly connected to the connecting rod and runs in the cylinder as a single unit — so one oil charge lubricates both the cylinder and the crankcase, unlike a crosshead 2-stroke which uses separate cylinder and system oils.

Which BN do I need for my genset?

It depends on fuel sulphur: distillate-fuelled auxiliaries usually take BN 12–30, residual-fuelled units BN 40–55. We'll match the engine-maker-approved grade to your fuel.

Do you carry approved grades for MAN, Wärtsilä and Yanmar auxiliaries?

Yes — TPEO grades with the relevant engine-builder approvals are part of our lubricant supply at all hubs.