7.
Lubricating Oil System
7.1
Lubricating oil requirements
7.1.1 Engine lubricating oil
The lubricating oil must be of viscosity class SAE 40 and have a viscosity index (VI) of minimum 95. The
lubricating oil alkalinity (BN) is tied to the fuel grade, as shown in the table below. BN is an abbreviation of
Base Number. The value indicates milligrams KOH per gram of oil.
Table 7.1 Fuel standards and lubricating oil requirements, gas and MDF operation
Lubricating oil BN
Fuel standard
Category
10...20
GRADE 1-D, 2-D
DMX, DMA
DA, DX
ISO-F-DMX, DMA
ASTM D 975-01,
BS MA 100: 1996
CIMAC 2003
ISO 8217: 2005(E)
A
15...20
DMB
DB
ISO-F-DMB
BS MA 100: 1996
CIMAC 2003
ISO 8217: 2005(E)
B
If gas oil or MDF is continuously used as fuel, lubricating oil with a BN of 10-20 is recommended to be
used. In periodic operation with natural gas and MDF, lubricating oil with a BN of 10-15 is recommended.
The required lubricating oil alkalinity in HFO operation is tied to the fuel specified for the engine, which is
shown in the following table.
Table 7.2 Fuel standards and lubricating oil requirements, HFO operation
Lubricating oil BN
Fuel standard
Category
30...55
GRADE NO. 4D
GRADE NO. 5-6
DMC, RMA10-RMK55
DC, A30-K700
ISO-F-DMC, RMA30-RMK700
ASTM D 975-01
ASTM D 396-04,
BS MA 100: 1996
CIMAC 2003,
ISO 8217: 2005 (E)
C
In installation where engines are running periodically with different fuel qualities, i.e. natural gas, MDF and
HFO, lubricating oil quality must be chosen based on HFO requirements. BN 50-55 lubricants are to be
selected in the first place for operation on HFO. BN 40 lubricants can also be used with HFO provided that
the sulphur content of the fuel is relatively low, and the BN remains above the condemning limit for acceptable
oil change intervals. BN 30 lubricating oils should be used together with HFO only in special cases; for ex-
ample in SCR (Selective Catalyctic Reduction) installations, if better total economy can be achieved despite
shorter oil change intervals. Lower BN may have a positive influence on the lifetime of the SCR catalyst.
It is not harmful to the engine to use a higher BN than recommended for the fuel grade.
Different oil brands may not be blended, unless it is approved by the oil suppliers. Blending of different oils
must also be approved by Wärtsilä, if the engine still under warranty.
An updated list of approved lubricating oils is supplied for every installation.
7.1.2 Oil in speed governor or actuator
An oil of viscosity class SAE 30 or SAE 40 is acceptable in normal operating conditions. Usually the same
oil as in the engine can be used. At low ambient temperatures it may be necessary to use a multigrade oil
(e.g. SAE 5W-40) to ensure proper operation during start-up with cold oil.
7.1.3 Oil in turning device
It is recommended to use EP-gear oils, viscosity 400-500 cSt at 40°C = ISO VG 460.
An updated list of approved oils is supplied for every installation.
68
Product Guide Wärtsilä 34DF - 3/2012
Product Guide
7. Lubricating Oil System
