System oils for crosshead crankcases.
A two-stroke crosshead engine separates its cylinder lubrication from its crankcase. The system oil circulates through bearings, the crosshead guide and the cooling circuit — a very different duty from the cylinder oil above it.
SYS 30 BN 5 — Everllence No Objection Letter
NOL No. 17679-2026, issued 12 March 2026 and valid to 12 March 2031. Scope: system oil, 5 BN, SAE 30, Group 1 — for Everllence B&W two-stroke engines.
See the documentsBN 5 or BN 6?
SYS 30 BN 5
The standard choice for modern Everllence B&W and WinGD crosshead engines, and the grade carrying the current No Objection Letter.
SYS 30 BN 6
Slightly higher alkaline reserve where cylinder oil carry-over into the crankcase is a known characteristic of the installation.
Guidance only. Follow the engine builder's prevailing system oil recommendation and your condition monitoring results.
Typical properties
| Product | TBNmgKOH/g | KV 100°CcSt | KV 40°CcSt | VI | Flash°C | Pour°C | Densityg/ml |
|---|---|---|---|---|---|---|---|
| SYS 30 BN 5 | 5.0 | 11.40 | 105.9 | 94 | 246 | -18 | 0.891 |
| SYS 30 BN 6 | 6.0 | 11.50 | 106.4 | 95 | 246 | -18 | 0.893 |
Both grades SAE 30, Group 1. Performance claims: MAN and WinGD. Typical values from Sinova Group technical data sheets (Form 002-EN, 5 January 2025).
Questions we get asked
What is marine system oil "3005" or "3006"?
Trade shorthand for an SAE 30 system oil with a base number of 5 or 6 — our SYS 30 BN 5 and SYS 30 BN 6. Both are crankcase oils for two-stroke crosshead engines; typical values from the data sheet are in the table above.
What is the difference between system oil and cylinder oil?
A crosshead engine keeps two environments apart with the stuffing box on the piston rod. Above it, cylinder oil (SAE 50, BN 40–140) is injected, does its work and is lost. Below it, system oil (SAE 30, BN 5–6) lubricates the main, crankpin and crosshead bearings, guides, thrust bearing and camshaft drive, cools the pistons, then drains to the sump, is filtered and purified, and stays in service for years.
Why a crosshead engine uses two different oilsWhat does an Everllence (MAN ES) No Objection Letter cover?
SYS 30 BN 5 holds Everllence No Objection Letter No. 17679-2026: system oil, 5 BN, SAE 30, Group 1, for Everllence B&W two-stroke engines, issued 12 March 2026 and valid to 12 March 2031. An NOL states that the engine builder does not object to the oil being used within that scope and period; it is not a performance endorsement, and it covers only the product, grade and engine types written on it.
Validated, approved, NOL or letter of supportWhy does a two-stroke main engine need two oils when an auxiliary engine manages with one?
Because of the crosshead layout. In a trunk piston auxiliary the connecting rod attaches directly to the piston and the crankcase sits open beneath it, so one circulating oil serves liner and bearings alike. In a crosshead engine the piston rod passes through a stuffing box that separates combustion from the crankcase, and each side gets the oil its own conditions demand.
The mechanical reason, in full