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, MDF operation
Fuel S content, [% m/m]
Lubricating oil BN
Fuel standard
Category
< 0.4
10...20
21-30*)
GRADE 1-D, 2-D, 4-D
DMX, DMA, DMB
DX, DA, DB
ISO-F-DMX - DMB
ASTM D 975-17,
BS MA 100: 1996
CIMAC 2003
ISO 8217:2017(E)
A
0.4 - 1.5
15...20
10-14)**)
21-30)*)
GRADE 1-D, 2-D, 4-D
DMX, DMA, DMB
DX, DA, DB
ISO-F-DMX - DMB
ASTM D 975-17
BS MA 100: 1996
CIMAC 2003
ISO 8217:2017(E)
B
*) Though the use of BN 21-30 lubricating oils is allowed in distillate fuel operation, there is no
technical reason for that but a lower BN level shown in the above table is well enough.
**) BN 10-14 lubricating oils cannot be recommended in the first place when operating on
>0,40% m/m sulphur distillate fuels due to shortened oil change interval resulting from BN
depletion.
Table 7-2
Fuel standards and lubricating oil requirements, HFO operation
Fuel S content, [% m/m]
Lubricating oil BN
Fuel standard
Category
≤
3.50 or statuatory require-
ments***)
30...55
GRADE NO. 4D
GRADE NO. 5-6
DMC, RMA10-RMK55
DC, A30-K700
RMA10-RMK700
ASTM D 975-17
ASTM D 396-17,
BS MA 100: 1996
CIMAC 2003,
ISO 8217:2017(E)
C
***) Sulphur content can be also higher than 3,50% m/m.
It is recommended to use in the first place BN 50 - 55 lubricants when operating on residual
fuel. This recommendation is valid especially for engines having wet lubricating oil sump and
using residual fuel with sulphur content above 2,0 % mass.
BN 40 lubricants can be used when operating on residual fuel as well if experience shows that
the lubricating oil BN equilibrium remains at an acceptable level.
In residual fuel operation BN 30 lubricants are recommended to be used only in special cases,
like e.g. such as installations equipped with an SCR catalyst. Lower BN products eventually
have a positive influence on cleanliness of the SCR catalyst.
With BN 30 oils lubricating oil change intervals may be rather short, but lower total operating
costs may be achieved because of better plant availability provided that the maintenance
intervals of the SCR catalyst can be increased.
If both distillate fuel and residual fuel are used in turn as fuel, lubricating oil quality has to be
chosen according to instructions being valid for residual fuel operation, i.e. BN 30 is the
minimum.
DAAB605814
7-1
7. Lubricating Oil System
Wärtsilä 46F Product Guide
Summary of Contents for 46F Series
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