Guidelines for Fuels and Lubes Purchasing - MAN Diesel & Turbo

Guidelines for Fuels and 

Lubes Purchasing 

Operation on Heavy Residual Fuels 

MAN Diesel

Contents 

MAN B&W Diesel 

Fuel Oil Quality ............................................................................................5 

Analysis Data ...............................................................................................6 

Fuel Oil Stability ...........................................................................................8 

Fuel Oil Treatment ........................................................................................8 

Centrifuging Recommendations ....................................................................9 

High Density Fuels ..................................................................................... 10 

Fuel Sampling ............................................................................................ 11 

Supplementary Fuel Oil Treatment .............................................................. 11 

Fuel Oil System .......................................................................................... 13 

Operational Aspects ................................................................................... 14 

Low-sulphur Fuel Operation ....................................................................... 15 

Off-spec. Fuels........................................................................................... 15 

Lubricating Oil Qualities .............................................................................. 16 

Lube Oil Blending on Board ........................................................................ 17 

Cylinder Oil, Low Speed Diesels ................................................................. 18 

Performance Verification of Cylinder Oils ..................................................... 19 

Fuels and Lubes for Stationary Two-stroke MAN B&W Engines .................. 19 

List of References ...................................................................................... 20 

Guidelines for Fuels and Lubes Purchasing Operation on Heavy Residual Fuels 

3

4 Guidelines for Fuels and Lubes Purchasing Operation on Heavy Residual Fuels

Guidelines for Fuels and Lubes Purchasing 

Operation on Heavy Residual Fuels 

MAN B&W Two-stroke Engines 

Fuel Oil Quality 

MAN Diesel’s engines are designed to 

operate in accordance with the unifuel 

principle. For specific guidelines for fuel 

and lube oils for gensets, contact MAN 

Diesel in Augsburg, Germany. 

For guidance on purchase, reference 

is made to ISO 8217, BS6843 and to 

Residual marine fuel standards 

Characteristic 

Density at 15 ºC 

Kinematic viscosity 

at 50 ºC 

Flash point 

Pour point (upper) 

b 

- winter quality 

- summer quality 

Unit 

kg/m 3 

mm 2 /s a 

ºC 

ºC 


Limit 

max. 

max. 

min. 

max. 

max. 

CIMAC recommendations regarding 

requirements for heavy fuel for diesel 

engines, edition 2003. According to 

these, the maximum accepted grades 

are RMH 55 and K55. The mentioned 

ISO and BS standards supersede BS 

MA 100, in which the limit is M9. 

Category ISO-8217 (Class F) 

RMA 

30 

960,0 

0 

6 

30,0 

60 

RMB 

30 

975,0 

24 

24 

RMD 

80 

980 

80.0 

60 

30 

30 

RME 

180 

991.0 

180.0 

60 

30 

30 

RMF 

180 

RMG 

380 

991.0 

RMH 

380 

380.0 

60 

30 

30 

For reference purposes, an extract from 

the relevant standards and specifica- 

tions is shown in Table I. 

Based on our general service experi- 

ence, and as a supplement to the above- 

mentioned standards, MAN Diesel issues 

a guiding fuel oil specification, shown 

in Table I. 

RMK 

380 

1010.0 

RMH 

700 

991.0 

700.0 

RMK 

700 

1010.0 

Test method 

reference 

ISO 3675 or ISO 

12185 (see also 

7.1) 

ISO 3104 


60 

30 

30 

ISO 2719 

(see also 7.2) 

ISO 3016 

ISO 3016 

Carbon residue %(m/m) max. 10 14 15 20 18 22 22 ISO 10370 

Ash %(m/m) max. 0.10 0.10 0.10 0.15 0.15 0.15 ISO 6245 

Water %(v/v) max. 0.5 0.5 0.5 0.5 0.5 ISO 3733 

Sulphur c 

Vanadium 

Total sediment 

potential 

Aluminium + 

Silicon 

Used lubricating 

oil (ULO) 

- Zinc 

- Phosphorus 

- Calcium 

%(m/m) 

mg/kg 

%(m/m) 

mg/kg 

mg/kg 

max. 

max. 

max. 

max. 

max. 

max. 

max. 

3.50 

150 

0.10 

80 

4.00 

350 

0.10 

80 

4.50 

200 

The fuel shall be free of ULO d 

15 

15 

30 

0.10 

80 

500 

300 

4.50 

0.10 

80 

600 

4.50 

600 

0.10 

80 

ISO 8754 or ISO 

14596 


ISO 14597 or IP 

501 or IP 470 

(see also 7.8 

ISO 10307-2 


ISO 10478 or IP 

501 or IP 470 


IP 501 or IP 470 

(see 7.7) 

IP 501 or IP 500 

(see 7.7) 

IP 501 or IP 470 

(see 7.7) 

a Annex C gives a brief viscosity/temperature table for information purposes only. (1 mm 2 /s = 1 cSt) 

b Purchasers should ensure that this pour point is suitable for the equipment on board, especially if the vessel operates in both the northern and southern hemispheres. 

c A sulphur limit of 1.5 % (m/m) will apply in SO x emission control areas designated by the International Maritime Organization, when its relevant protocol comes into force. 

There may be local variations. 

d A fuel must be considered to be free of ULO if one or more of the elements zinc, phosphorus and calcium are below or at the specified limits. All three elements must exceed the 

same limits before a fuel shall be deemed to contain ULO. 

Table II 

5

In both tables the data refers to fuel 

oils as delivered to the ship, i.e. before 

onboard cleaning. Fuel oils within the 

limits of this specification have, to the 

extent of their commercial availability, 

been used with satisfactory results in 

MAN B&W two-stroke low speed diesel 

engines. 

It should be noted that current analysis 

results do not fully suffice for estimating 

the combustion properties of fuel oils. 

This means that service results could 

depend on oil properties which are not 

known beforehand. This applies espe- 

cially to the tendency of the fuel oil to 

form deposits in combustion cham- 

bers, gas passages and turbochargers. 

As mentioned, the data refers to the fuel as 

supplied, i.e. before the treatment. 

If a fuel oil exceeding the data in Table I is 

to be used, the engine builder or MAN 

Diesel should be contacted for advice. 

Analysis Data 

Viscosity 

Viscosity cannot be considered a qual- 

ity criterion in its own right for fuel oils, 

and is stated only for handling reasons 

(pumps, preheaters and centrifuges). 

Density 

Density is related to the fuel quality be- 

cause fuels derived from extensive re- 

finery processing are left with a higher 

carbon content, are more aromatic 

and thus heavier. Therefore, fuels with 

a high density are also high in carbon 

residue and asphaltenes. 

The water separation ability of the fuel 

oil is ensured by limiting the density for 

reasons of centrifuging, as stated in the 

specification. 

Density is normally measured at higher 

temperatures, and the density at 15°C 

is calculated on the basis of tables 

which, depending on their origin, date 

of issue, and the data on which they are 

based, could give slightly differing den- 

sities at 15°C. 

Whereas the limit of 991 kg/m 3 must 

be observed when traditional centrifuges 

(before 1985, purifier – clarifier) are used, 

1010 kg/m 3 is accepted provided that 

modern centrifuges capable of hand- 

ling fuels of such density are installed. 

Flash point 

The flash point limit is set as a safeguard 

against fire only. 

Pour point 

The pour point indicates the minimum 

temperature at which the fuel should 

be stored and pumped. Temperatures 

below the pour point results in wax for- 

mation. 

Sulphur 

The corrosive effect of sulphuric acid 

during combustion is counteracted by 

adequate lube oils and temperature 

control of the combustion chamber 

walls. 

The cylinder lube oil feed rate must be 

according to the MAN Diesel recom- 

mendation. The sulphur content has a 

negligible effect on the combustion proc- 

ess. 

Carbon residue 

The carbon residue is measured as 

Conradson Carbon or Microcarbon. 

6 Guidelines for Fuels and Lubes Purchasing Operation on Heavy Residual Fuels 

Fuels with a high carbon residue con- 

tent could cause increased fouling of 

the gasways, necessitating more fre- 

quent cleaning, especially of the turbo- 

charger and exhaust gas boiler. 

Some changes in combustion, requir- 

ing adjustment of maximum pressures 

for reasons of economy, could also be 

attributed to a high carbon residue con- 

tent. Part of the carbon residues repre- 

sents asphaltenes. 

The effect of asphaltenes on the com- 

bustion process is similar to that of the 

carbon residue. Asphaltenes also af- 

fects the fuel oil lubrication properties. 

Fuels with a high content of asphaltenes 

may tend to emulsify with water. 

Water 

Water in the fuel should be removed by 

centrifuging the fuel before use. This 

applies especially to salt water, the 

sodium content of which can result in 

deposits on valves and turbochargers. 

If the water cannot be removed online, 

homogenising after centrifuging is recom- 

mended. 

Ash 

Ash represents solid contaminants as 

well as metals bound in the fuel (e.g. 

vanadium and nickel). Part of the ash 

could be catalyst particles from the refin- 

ing process. 

Catalyst particles are highly abrasive. 

Solid ash should be removed to the 

widest possible extent by centrifug- 

ing, and cleaning can be improved by 

installing a fine filter after the centrifuge 

(e.g. 50 μm).

Vanadium, magnesium and sodium 

Vanadium is bound in chemical com- 

plexes in the fuel and, consequently, 

cannot be removed. 

Vanadium deposits can be very hard, 

and may cause extensive damage to 

the turbocharger nozzle ring and tur- 

bine wheel. The only way to remove 

vanadium deposits is to disassemble the 

components and erase the deposits me- 

chanically. 

Sodium is normally present in the fuel 

as a salt water contamination and may, 

as such, be removed by centrifuging. 

Sodium can also reach the engine in 

the form of airborne sea water mist. 

Vanadium, in combination with sodium, 

may lead to exhaust valve corrosion 

and turbocharger deposits. This can 

occur especially if the weight ratio of 

sodium to vanadium exceeds 1:3, and 

especially in the case of a high vana- 

dium content. 

MAN Diesel has limited data to show 

that the level of sodium and vanadium 

in combination, and in this ratio, has led 

to the above-mentioned complications 

on MAN B&W engines. 

For lower contents of sodium and va- 

nadium, the weight ratio is considered 

of less importance (for a vanadium con- 

tent less than 150 mg/kg). 

Magnesium, either present in the fuel, 

in salt water contamination or intro- 

duced via additives can, to some ex- 

tent, increase the melting point of the 

vanadium, thus preventing the forma- 

tion of deposits. 


Aluminium and silicon 

The limit to aluminium and silicon has 

been introduced in order to restrict the 

content of catalytic fines, mainly Al 2 O 3 

and SiO 2 , in the oil. 80 mg Al and Si 

corresponds to up to 170 mg Al 2 O 2 and 

SiO 2 . 

Catalytic fines give rise to abrasive 

wear, and their content should, there- 

fore, be reduced as much as possible 

by centrifuging the fuel oil before it 

reaches the engine. 

MAN Diesel recommends that 80 ppm 

of catalytic fines before the centrifuge 

is reduced as much as possible by the 

fuel centrifuge and, as a guideline, the 

level should in any case not exceed 15 

ppm after the centrifuge, see Ref. [1] 

and Ref [2]. 

Ignition quality 

Normally applied analytical data for fuel 

oil contain no direct indication of igni- 

tion quality, neither do current specifi- 

cations and standards. However, this is 

not an important parameter for engines 

with high compression ratios. 

In a few cases (less than five), we have 

observed that the fuel had such poor 

ignition quality that the engines could 

not operate properly. Analysis of the 

fuel in question revealed that these 

fuels had all been contaminated by 

chemical waste. 

Tests performed together with fuel ana- 

lysing institutes give indications of the 

ignition and combustion qualities of the 

different fuels. Test instruments utilising 

a constant volume combustion technol- 

ogy have been developed and are cur- 

rently being used for marine fuel testing 

at a number of fuel laboratories and build- 

ers of marine diesel engines worldwide. 

The test presents the Rate of Heat Re- 

lease, reflecting the actual heat release 

process and, thus, the combustion 

quality of the fuel tested. By the use of 

calibration fuels, a recorded ignition de- 

lay in combination with the combustion 

quality can be converted into an instru- 

ment-related Cetane number. 

The test results reflect the differences 

in ignition and combustion properties of 

diesel engine fuels resulting from varia- 

tions in the chemical composition of the 

fuels being tested. 

However, these test results do not re- 

flect the functions of the actual com- 

bustion in the diesel engine, because 

the tests are conducted at different 

conditions/mechanisms than exist in 

the engine. 

With the modern high compression ra- 

tio engines, the denoted differences in 

the fuel, both good and bad, are not at 

the level indicated by the test results. 

The cetane number in an ignition qual- 

ity test might, as such, only provide an 

indication of the difference in the fuels, 

but not whether this will have an influ- 

ence on the engine performance. 


7

Fuel Oil Stability 

Fuel oils are produced on the basis of 

widely varying crude oils and refinery 

processes. Due to incompatibility, such 

fuels can occasionally tend to be unsta- 

ble when mixed, for which reason mix- 

ing on board should be avoided to the 

widest possible extent. 

A mixture of incompatible fuels in the 

tanks can result in rather large amounts 

of sludge being taken out by the centri- 

fuges or even lead to centrifuge blocking. 

Inhomogeneity in the service tank can 

be counteracted by recirculating the 

contents of the tank through the cen- 

trifuge. This will have to be carried out 

Diesel oil 

service 

tank 

From centrifuges 

Booster 

pump 

- - - - - - - - - - Diesel oil 

Heavy fuel oil 

Heated pipe with insulation 

at the expense of the benefits derived 

from a low centrifuge flow rate as de- 

scribed below. 

With the introduction of new IMO emis- 

sion regulations and the fuel sulphur 

limit in SECAs (sulphur emission control 

areas), more blending of fuels to com- 

ply with the regulations is taking place. 

For this reason, the risk of incompat- 

ibility of fuels is also higher. 

Fuel Oil Treatment 

Fuels supplied to a ship must be treat- 

ed on board before use. Detailed infor- 

mation on fuel oil system layout can be 

found in the CIMAC Recommendations 

issued in 2005, Volume 9, concerning the 

Deck 


service tank 

Overflow valve 

adjusted to 4 bar 

Supply pumps Circulating 

pumps 

Auxiliary 

engines 

Fig. 1: Pressurised uni-fuel oil system for both main engine and gensets 


Automatic de-aerating valve 

Venting box 

Common fuel oil supply unit 

Full flow filter 

Heater 

Auxiliary 

engines 

To fresh water cooling 

pump suction 

design of heavy fuel treatment plants for 

diesel engines. Practically all fuel speci- 

fications refer to fuel as supplied and, 

as such, serve primarily as purchasing 

specifications. Furthermore, the data in 

a standard fuel analysis serves to ad- 

just the onboard treatment and is ac- 

tually of little use to the operator when 

referring to the engine operational data. 

Hence the basic design criterion is that 

engines must be capable of accepting 

all commercially available fuel oils, pro- 

vided that they are adequately treated 

on board. 

For this purpose, a well-designed fuel 

oil treatment system is a must. General 

Fuel oil 

drain tank 

Main engine 

Auxiliary 

engines

minimum recommendations for the lay- 

out of such a system have been speci- 

fied and should be complied with in 

order to ensure proper treatment of the 

fuel permitted by the guiding specifica- 

tion. The operation of the fuel prepara- 

tion system is the responsibility of the 

operator. Good results require both the 

correct system and the correct opera- 

tion of the system. 

The fuel oil system consists of a clean- 

ing plant (comprising centrifuging) and 

a pressurised fuel oil system. 

Fig. 1 shows the pressurised fuel oil 

system common for MAN B&W main 

and GenSet engines. 

Centrifuging Recommendations 

Fuel oils, whether HFO or DO, should 

always be considered as contaminated 

upon delivery and should therefore be 

thoroughly cleaned to remove solid as 

well as liquid contaminants before use. 

The solid contaminants in the fuel are 

mainly rust, sand, dust and refinery cat- 

alysts. Liquid contaminants are mainly 

water, i.e. either fresh water or salt wa- 

ter. 

Impurities in the fuel can cause damage 

to fuel pumps and fuel valves, and can 

result in increased cylinder liner wear 

and deterioration of the exhaust valve 

seats. Also increased fouling of gas- 

ways and turbocharger blades could 

result from the use of inadequately 

cleaned fuel oil. 

Effective cleaning can only be ensured 

by using a centrifuge. We recommend 

that the capacity of the installed centri- 


fuges should, at least, be according to 

the centrifuge maker’s specifications. 

To obtain optimum cleaning, it is of the 

utmost importance that the centrifuge 

is operated with as low a fuel oil viscos- 

ity as possible, and that the fuel oil is al- 

lowed to remain in the centrifuge bowl 

for as long as possible. 

Temperature of HFO before centri- 

fuges 

It is often seen that the HFO preheat- 

ers are too small, or the steam supply 

of the preheater is limited, or that they 

have too low a set point in tempera- 

ture. Often the heater surface is partly 

clogged by deposits. These factors all 

lead to reducing the separation tem- 

perature and hence the efficiency of the 

centrifuge. 

In some cases, the temperature of the 

HFO from the preheater is unstable and 

fluctuates, which again results in im- 

proper cleaning of the fuel. 

In order to ensure that the centrifugal 

forces separate the heavy contaminants in 

Capacity for same separation (%) 

100 

90 

80 

70 

180 cSt 

300 cSt 

700 cSt 

the relatively limited time that they are 

present in the centrifuge, the centrifuge 

should always be operated with an inlet 

temperature of 98°C. 

A temperature decrease has to be fol- 

lowed by a reduced throughput to en- 

sure the same cleaning efficiency, see 

Fig. 2. 

The fuel is kept in the centrifuge as long 

as possible by adjusting the flow rate 

through the centrifuge so that it corre- 

sponds to the amount of fuel required 

by the engine without excessive recir- 

culation. Consequently, the centrifuge 

should operate for 24 hours a day ex- 

cept during necessary cleaning. 

Centrifuges with separate feed pumps 

with a capacity matched to the engine 

output are to be preferred. 

Taking today’s fuel qualities into con- 

sideration, the need for maintenance of 

the centrifuges should not be underes- 

timated. 

77 90 92 94 96 98 100 

o 

cSt at 50 C 

Fig. 2: Relationship of throughput and temperature 


9

On centrifuges equipped with adjusting 

screws and/or gravity disks, their cor- 

rect choice and adjustment is of special 

importance for the efficient removal of 

water. 

The centrifuge manual states which 

disk or screw adjustment should be 

chosen on the basis of the density of 

the fuel. 

The normal practice is to have at least 

two centrifuges available for fuel clean- 

ing purposes, operating in serial or par- 

allel mode. 

For old type centrifuges, results from 

experimental work on the centrifuge 

treatment of today’s residual fuel quali- 

ties have shown that the best cleaning 

effect, particularly in regard to removal 

of catalytic fines, is achieved when the 

centrifuges are operated in series, i.e. 

in purifier/clarifier mode. 

For the automatically operating centri- 

fuges delivered from the mid-1980s, 

suitable for treating fuels with densi- 

ties higher than 991 kg/m 3 at 15°C, it 

is recommended to operate the centri- 

% Rate of flow, related to rated capacity of centrifuge 

80 

60 

40 

20 

fuges in parallel, as this results in reduced 

throughput, i.e. longer retention time in the 

centrifuge. However, the maker’s specific 

instructions should be followed. 

In this context, see section on high 

density fuels. If the centrifuge capacity 

installed is on the low side, in relation 

to the specific viscosity of the fuel oil 

used, and if more than one centrifuge is 

available, parallel operation should be 

considered as a means of obtaining an 

even lower flow rate. However, in view 

of the above results and recommenda- 

tions, serious consideration should be 

given to installing new equipment in 

compliance with today’s fuel qualities 

and flow recommendations. 

For determination of the centrifuging 

capacity, we generally advise that the 

recommendations of the centrifuge 

maker be followed, but the curves in 

Fig. 3 can be used as a guide. 

It is recommended that new centrifuges 

have gone through a separation perfor- 

mance standard test according to the in- 

dustry standard CWA 15375. 

200 400 600 1500 3500 7000 sec RI/100 F 

o 

Fig. 3: Centrifuge makers´ capacity specification 


In order to check the performance of 

the centrifuge, fuel samples taken reg- 

ularly before and after the centrifuge 

should be analysed. 

High Density Fuels 

In view of the fact that some fuel oil 

standards incorporate fuel grades with- 

out a density limit, and also the fact 

that the traditional limit of 991 kg/m 3 

at 15°C is occasionally exceeded on 

actual deliveries, some improvements 

in the centrifuging treatment have been 

introduced to enable treatment of fuels 

with higher density. 

Since the density limit used so far is, as 

informed by centrifuge makers, given 

mainly to ensure interface control of the 

purifier, new improved clarifiers, with 

automatic desludging, have been in- 

troduced, which means that the purifier 

can be dispensed with. 

With such equipment, adequate sepa- 

ration of water and fuel can be carried 

out in the centrifuge, for fuels up to a 

density of 1010 kg/m 3 at 15°C. 

Therefore, this has been selected as 

the density limit for new high density 

fuel grades. 

Thus we have no objections to the use of 

such high density fuels in our engines, 

provided that these types of centrifuges 

are installed. They should be operated 

in parallel or according to the centri- 

fuge maker’s instructions.

Fuel Sampling 

Sampling 

To be able to check whether the speci- 

fication indicated and/or the stipulated 

delivery conditions have been complied 

with, we recommend that a minimum 

of one sample of each bunker fuel lot 

be retained. In order to ensure that 

the sample is representative for the oil 

bunkered, the sample should be con- 

tinuously taken at the ship manifold 

throughout the bunkering period. This 

is done by a continuous collection of 

drip sample during the bunker delivery, 

see Ref. [3]. 

This is without including the BDN (bun- 

ker delivery note) for compliance with 

IMO Annex VI. 

Analysis of samples 

The samples received from the bunker- 

ing company are frequently not identi- 

cal with the heavy fuel oil actually bun- 

kered. It is also appropriate to verify the 

heavy fuel oil properties stated in the 

bunker documents, such as density, 

viscosity and pour point. If these values 

deviate from those of the heavy fuel oil 

bunkered, there is a risk that the heavy 

fuel oil separator and the preheating 

temperature are not set correctly for the 

given injection viscosity. 

Sampling equipment 

Several suppliers of sampling and fuel 

test equipment are available on the 

market, but for more detailed and ac- 

curate analyses, a fuel analysing insti- 

tute should be contacted. 


Supplementary Fuel Oil Treatment 

In a traditional system, the presence of 

large amounts of water and sludge will 

hamper the functioning of a clarifier, for 

which reason a purifier has been used 

as the first step in the cleaning process. 

With the new automatic desludging 

clarifiers, the purifier can, as mentioned, 

be dispensed with. We consider the re- 

moval of solids to be the main purpose 

of fuel treatment. 

Although not necessarily harmful in its 

own right, the presence of an uncon- 

trolled amount of water and sludge in 

the fuel makes it difficult to remove the 

solid particles by centrifuging. 

Therefore, the following additional equip- 

ment has been developed: 

Homogenisers 

Homogenisers are used to disperse 

any sludge and water remaining in the 

fuel after centrifuging. A homogeniser 

placed after the centrifuge will render 

fresh water (not removed by centrifug- 

ing) harmless to the engine. 

Homogenising may also be a means 

to cope with the more and more fre- 

quently occurring incompatibility prob- 

lems, which are not really safeguarded 

against in any fuel specification. Both 

ultrasonic and mechanical homogenis- 

ers are available. 

Homogenisers can also be used for 

moderate emission control in conjunc- 

tion with emulsification of freshwater 

into the fuel. 

Homogenisers installed before the fuel 

centrifuge can, when considering the 

full range of the ISO 8217 fuel speci- 

fi-cation, reduce the efficiency of the 

centrifuge and, thus, the cleanliness of 

the fuel delivered to the engine. The so- 

dium will not be removed from the fuel 

in the form of salt water. The cat fines 

and other abrasive material might be 

split up into very small particles, which 

are difficult for the centrifuge to sepa- 

rate and which will still have a harmful 

wear effect on the engine components. 


11

To drain tank 

F.O. drain 

tank 

Main 

engine 

TSA 

TE 8005 

304 

Automatic de�aerating valve 

To F.W. cooling 

pump suction Full flow filter 

Diesel oil 


Heated pipe with insulation 

Fig. 4: Pressurised fuel oil system, with homogeniser 

Installation of homogenisers before the 

centrifuge, see Fig. 4, is therefore not 

advisable. 

In order to reduce the NOx level in the 

engine exhaust gas, water can be added 

to the fuel oil to create an emulsion. 

Clean freshwater should be used, and 

this is homogenised into the fuel oil at 

PI PI 

PT 

PSA 

8002 

307 

TI TI 

Venting tank 

Circulating pumps 


VSA 

303 

Pre� 

heater 

VT 8004 


service tank 

Deck 

Supply pumps 

Acceptable location 

of homogeniser 

a maximum ratio of approx. one part of 

water to two parts of fuel oil. The water 

emulsion can be stable with HFO but 

with lighter fuels, such as gas oil and 

diesel oil, it may be necessary to add 

an emulsifier to the fuel oil before homogenising 

the fuel and water. The homogeniser 

is located between the HFO 

service tank and the engine, i.e. after 

the fuel oil purifiers. 

Suggested location of homogeniser 

by some suppliers. 

Not acceptable 

for engine performance 

Diesel 

oil 

service 

tank 

Fine filters 

Centrifuges 

From diesel centrifuges 

Fuel 

storage 

tank 

Fine filters are placed directly after the 

centrifuge, or in the supply line to the 

engine, in order to remove any solid 

particles not taken by centrifuging. The 

mesh is very fine, i.e. down to 5 μm. 

Homogenising before a fine filter can 

reduce the risk of fine filter blocking by 

the agglomeration of asphaltenes.

Temperature after heater 

o 

C 

170 

160 

150 

140 

130 

120 

110 

100 

90 

80 

70 

60 

50 

40 

Fuel Oil System 

A pressurised fuel oil system, as shown 

in Fig. 1, is necessary when operating 

on high viscosity fuels. When using high 

viscosity fuels requiring high preheating 

temperatures, the oil from the engine 

fuel oil system to the return line will also 

have a relatively high temperature. 

The fuel oil pressure measured on the 

engine (at fuel pump level) should be 

about 8 bar, which is equivalent to a cir- 

culating pump delivery pressure of up 

to 10 bar. This maintains a pressure mar- 


Normal heating limit 

Approximate pumping limit 

cSt Sec 

RW 

7 43 

10 52 

12 59 

15 69 

20 87 

30 125 

10 15 25 35 45 55 cSt/100 C 

o 

30 60 100 180 380 600 cSt/50 C 

o 

200 400 800 1500 3500 6000 sec. RW/100 F 

o 

30 

Viscosity of fuel 

Fig. 5: Heating chart for heavy fuel oil 

Approximate viscosity 

after heater 

gin against gasification and cavitation in 

the fuel system, even at 150°C preheat. 

In order to ensure correct atomisation, 

the fuel oil temperature must be ad- 

justed according to the specific fuel oil 

viscosity used. 

An inadequate temperature can influ- 

ence the combustion and could cause 

increased wear on cylinder liners and 

piston rings, as well as deterioration 

of the exhaust valve seats. Too low a 

heating temperature, i.e. too high vis- 

cosity, could also result in a too high 

injection pressure, leading to excessive 

mechanical stresses in the fuel oil sys- 

tem. 

In most installations, heating is carried 

out by means of steam, and the viscosity 

is kept at the specified level by a viscosity 

regulator controlling the steam supply. 

Depending on the viscosity/tempera- 

ture relationship of the fuel oil (the vis- 

cosity index), an outlet temperature of 

up to 150°C might be necessary, as in- 

dicated on the guidance curves shown 

in Fig. 5, which illustrate the expected 

heating temperature as a function of the 

specific fuel oil viscosity in cSt/50°C. 

The recommended viscosity meter set- 

ting is 10-15 cSt. However, service ex- 

perience has shown that the viscosity 

of the fuel before the fuel pump is not 

a too critical parameter, for which rea- 

son we allow a viscosity of up to 20 cSt 

after the heater. In order to avoid too 

rapid fouling of the heater, the temper- 

ature should not exceed 150°C. 


13

Operational Aspects 

All low speed engines from and in- 

cluding the K-GF types (from around 

1973) are equipped with uncooled, all- 

symmetrical lightweight fuel injection 

valves. 

These allow constant operation on 

heavy fuel, due to the built-in possibility 

of circulating heated heavy fuel through 

the high-pressure fuel pipes, and fuel 

valves during engine standstill. 

In view of the emission regulations and 

the increased use of low-sulphur fuels, 

a special procedure is made to protect 

the engine when changing between fu- 

els (see the chapter: ‘‘Low-sulphur Fuel 

Operation’’). 

If a change to diesel oil is necessary as 

a result of, for instance, the need for 

a major repair of the fuel oil system, a 

prolonged stop, or the use of very low- 

sulphur fuels, as required by environ- 

mental legislation, the heavy fuel in the 

system can be changed with diesel oil 

at any time, provided the change-over 

procedure is followed, even when the 

engine is not running. See also the en- 

gine instruction book. 

During engine standstill, the heated fuel 

oil circulating through the fuel system 

does not require the same low viscosity 

as recommended for injection. 

Thus, in order to save steam, the heat- 

ing temperature may be lowered by 

some 20°C, giving the circulating oil a 

viscosity of up to 30 cSt. 

The temperature should be raised to 

the recommended service value, as il- 

lustrated in Fig. 5, about 30 minutes 

before starting-up is expected. 

As previously mentioned, the heating 

temperature must not exceed 150°C, 

and during operation it is not necessary 

to apply pipe heating by means of heat 

Compatibility 

of mixed fuels! 

Tank system 

considerations! 

High S% 


Fuel change-over unit 

Engine 

Low S% 

tracing. When running on diesel oil, the 

heat tracing system must not be used 

at all. 

However, it should be noted that the 

pipe heating system on drain pipes 

should remain in operation when run- 

ning on heavy fuel. 

Fig. 6: Considerations to be made to before changing between high/low sulphur fuels 

Fig. 7: Recommended cylinder oil feed rates depending on the fuel sulphur level 

Oil 

Viscosity! 

BN 

10-40-70!

Low-sulphur Fuel Operation 

Today, there are ECAs (emission control 

area, based on EU and IMO regulations) 

in the Baltic Sea, the North Sea and the 

English Channel. And more such areas 

are expected to come. In the USA, the 

EPA (Environmental Protection Agency) 

is considering to designate Long Beach 

an ECA very soon. 

The sulphur content has an impact on 

the sulphur acid emission to the air, sea 

and land, as well as a major impact on 

the particle level in the exhaust gas. 

Even though MAN B&W two-stroke en- 

gines are largely insensitive to the fuel 

quality, changing between fuels with 

different levels of viscosity is an impor- 

tant consideration to make. 

The cylinder lube oil base number must 

be considered. Operating on normal 

BN70 cylinder oil for too long when 

burning low-sulphur fuel will prevent 

controlled corrosion on the cylinder lin- 

ers. 

The mechanism is a creation of an ex- 

cess of deposits originating from the 

cylinder oil’s additives. Low-BN oil is 

available from the major oil companies, 

and recommendations on the use of 

low and high-BN oils are also available. 

The fuel change-over process must fol- 

low the thermal expansion of both the 

fuel pump plunger and the barrel, and 

a procedure has been created to avoid 

causing damage to the fuel pumps. 

An automatic change-over unit will be 

available in 2009. 

In order to ensure the creation of a hy- 

drodynamic oil film between the fuel 

pump plunger and barrel, a viscosity 


of 2 cSt is required at the engine in- 

let. This may be difficult to achieve for 

some DO and GOs, and some opera- 

tors may have to introduce a cooler in 

the fuel oil system to ensure a satisfac- 

tory viscosity level. 

The ignition quality of a fuel oil is not 

an issue for MAN B&W two-stroke en- 

gines. MAN Diesel has conducted a 

number of research tests showing that 

the MAN B&W two-stroke engine is in- 

sensitive to the poor ignition combus- 

tion quality fuels on the market today. 

A separate booklet called ‘‘Low-sulphur 

fuel operation’’ is available from MAN 

Diesel, Ref. [4]. 

Off-spec. Fuels 

Several selected off-spec. fuels (i.e. 

beyond ISO 8217) have been tested 

on MAN B&W’s two-stroke research 

engine: 

Natural gas 

Bitumen 

Orimulsion 

Tallow 

Our research facility in Copenhagen is 

available for such testing. In the event 

that off-spec. fuels are considered for 

use on MAN B&W engines, it is recom- 

mended that MAN Diesel is contacted 

for further information regarding opera- 

tional experience and any necessary 

precautions. 

Table II shows the guiding biofuel spec- 

ification for MAN B&W two-stroke low 

speed diesel engines. 

MAN Diesel can be contacted for fur- 

ther recommendations on the use of 

biofuels. 

Guiding Biofuel Specification for MAN B&W 

Two-stroke Low Speed Diesel Engines 1) 

Designation 

Density at 15 o C kg/m 3 1010 

Kinematic viscosity at 10 o C 2) 

cSt 55 

Flash point o C >60 

Carbon residue % (m/m) 22 

Ash % (m/m) 0.15 

Water % (m/m) 1.0 

Sulphur 3) % (m/m) 5.0 

Vanadium ppm (m/m) 600 

Aluminium + Silicon mg/kg 80 

Sodium plus potassium ppm (m/m) 200 

Calcium ppm (m/m) 200 

Lead ppm (m/m) 10 

TAN (Total Acid Number) mg KOH/g 4)

Lubricating Oil Qualities 

Low speed diesel rust and oxidation in- 

hibited alkaline engine oils of the SAE 

30 viscosity grade should be chosen 

for circulating oil. The oils should have 

adequate dispersancy/detergency to 

keep the crankcase and the piston 

cooling spaces free from deposits. 

For engines with an integrated gear 

driven Power Take Off (PTO), a mini- 

mum FZG load level (Foursquare gear 

oil test) of 8 should be observed. For 

electronically controlled engines, a min- 

imum FZG load level of 10 is required. 

Contamination of system lube oil 

Increase of BN (Base Number) and vis- 

cosity of the system lube oil during op- 

eration is unavoidable. 

The piston rod stuffing box separates 

the combustion and scavenge air 

spaces from the crankcase. Therefore, 

Table III 

lube oil will not be severely contami- 

nated with combustion products and 

used cylinder lube oil. However, some 

cylinder lube oil leaks through the stuff- 

ing box, down into the system lube oil 

sump. This is revealed by increasing 

BN and viscosity levels of the system 

lube oil. 

Normally, the increase will stop after 

some time and remain at a stable level 

where topping up with new system lube 

oil, to make up for normal consump- 

tion, will balance the degree of contam- 

ination of the system oil with cylinder 

lube oil. 

Water may also contaminate system oil. 

Excess water levels may harm tin-alu- 

minum bearings, for which reason MAN 

Diesel recommends that the water level 

does not exceed 0.2% (0.5% water al- 

lowed for shorter periods of time), Ref. 


[5]. 

In some cases, fuel has been seen 

leaking through the fuel pump umbrel- 

la sealings into the system oil. Fuel is 

known to form deposits on hot spots, 

i.e. in the piston undercrown space. It 

is therefore important to keep the rec- 

ommended overhaul intervals on fuel 

pumps to secure that the pump pack- 

ings/sealings are replaced. 

BN level consideration 

The increase in BN can influence the 

ability of the oil to reject water by the 

usual centrifuging. Water together with 

calcium compounds from oil additives 

may form calcium hydroxide recom- 

mended to ensure calcium carbonate 

and build up a deposit of lacquer on 

the bearings. Another risk is the in- 

creased sludge formation when water 

is present. 

Experience shows, however, that many 

engines are operating with up to 30 BN 

International brands of lubricating oils which have been applied with satisfactory results on MAN B&W engines, 

on a large number of vessels 

Lubricating oils - Low speed main engines 

Type Circulating oil Cylinder oil 

Requirement SAE 30, BN 5-10 SAE 50, BN 60-80 SAE 50, BN 40-50 

Oil company 

BP Energol OE-HT 30 Energol CLO-50M/CL 605 Energol CL 505/CL-DX 405 

Castrol CDX 30 Cyltech 70/80 AW Cyltech 40 SX/50 S 

Chevron 

(Chevron, Texaco, Caltex) 

Veritas 800 Marine 30 

Taro Special HT 70 

Taro Special HT LS 40 

Total Atlanta Marine D 3005 Talusia HR 70/Talusia Universal Talusia LS 40 

Exxon Mobil Mobilgard 300 Mobilgard 570 Mobilgard L540 

Shell Melina 30/30S Alexia 50 Alexia LS 

* depending on load profile and sulphur content, see MD recommendation for cylinder feed rate

(starting from approx. 6 BN) without 

any operational problems, and without 

any changes in the lube oil performance 

that give reason for renewing the oil. 

An increase in BN to an equilibrium 

value of up to 25 in BN and in viscosity 

from SAE 30 to SAE 40 is considered 

normal, and no action is called for. An 

increase beyond that is not really harm- 

ful and can, in most cases, be counter- 

acted by new low-BN topping oil. 

The circulation oil consumption on the 

MC/ME/ME-B/C/S engines is very low 

because the engines are designed to 

have fewer leaks and because of the 

much reduced stuffing box oil drain, 

compared to previous engine types, 

causing a higher increase in BN and 

viscosity. Therefore, it may be neces- 

sary to add some new oil to the lube oil 

sump at times to ensure a proper qual- 

ity and BN level of the lube oil. This is 

done by exchanging part of the circula- 

tion oil in the sump based on an analysis 

of the oil. 


Lube Oil Blending on Board 

A new blending-on-board (BoB) con- 

cept makes it possible to add addi- 

tives to the engine system oil and then 

utilise it as cylinder lube oil. By top- 

ping up the thereby used system oil, 

a steady renewal of the oil is ensured 

as well as improved viscosity control 

and cleanliness. The oil suppliers get 

the advantage of supplying only one oil 

and a limited amount of additives. The 

traditionally consumed cylinder oil is re- 

placed with the blended lube oil. 

Furthermore, the idea with the BoB 

concept is that the operator will ulti- 

mately be able to adjust the cylinder oil 

BN to the current fuel sulphur level by 

changing the blending ratio. In 2007, 

MAN Diesel issued a No Objection Let- 

ter (NOL) on a BN70 blend. The NOL 

applies to a specific additive in a spe- 

cific system oil. 

Testing of a BN60 blend on is ongoing, 

on an engine in service, and the condi- 

tion is so far found to be satisfactory. 

Technically, it is currently being investi- 

gated how the blending-on-board con- 

cept could cover all BN levels on just 

the same additive package. 

Some considerations must be made in 

this respect: 

System oil condition prior to blending 

must be acceptable 

Quality control of the additives must 

be ensured 

Technical performance of additive 

package in different concentrations 

(BN40, BN50, BN60…) must be 

clarified 

MAN Diesel shares a common inter- 

est with the oil companies – to keep 

the lube oil expenses predictable and 

optimal. Therefore, also in this field it 

is of the utmost importance to ensure 

the reliable performance of the blended 

products. This requires continuous ver- 

ification tests. 

No-objection letters will be issued as 

the tests with BoB and lower BN oils 

are successfully concluded. 

MAN Diesel can be contacted for infor- 

mation on the test status. 


17

Cylinder Oil, Low Speed Diesels 

For engines operating on heavy residual 

fuel oil, a cylinder oil with a viscosity of 

SAE 50 and BN of 70 is recommended. 

In most cases the high BN cylinder lubri- 

cant will also be satisfactory during tempo- 

rary operation on diesel oil/gas oil. 

In general, changing the cylinder oil 

type to correspond to the fuel type 

used (i.e. bunker fuel or diesel oil/gas 

oil) is considered relevant only in cases 

where operation on the respective fuel 

type is to exceed two weeks. However, 

cylinder oil feed rate adjustments might 

be required. 

There is a high risk when using BN70 

cylinder oils in connection with frequent 

bunkering of low-sulphur fuels, with a 

sulphur content of below to 1.5%, see 

Ref. [6] 

The main problem has been the ac- 

cumulation of unused cylinder oil ad- 

ditives, resulting in excessive deposits 

on the piston topland. This has led to 

high wear, and to a situation where in- 

creased lubrication does not improve 

the condition. On the contrary, in- 

creased lubrication increases the for- 

Stationary applications 

mation of deposits, leading to accelera- 

tion of the problem. 

It has been established that a certain 

degree of controlled corrosion en- 

hances lubrication, in that the corro- 

sion generates small “pockets” in the 

cylinder liner running face from which 

hydrodynamic lubrication from the oil in 

the pocket is created. The alternative, 

no corrosion, could lead to bore polish 

and, subsequently, hamper the crea- 

tion of the necessary oil film on the liner 

surface, resulting, eventually, in accel- 

erated wear. Controlled corrosion – not 

avoiding corrosion – is therefore crucial, 

and adjusting the BN to the fuel oil sul- 

phur content is essential. 

Low alkaline cylinder lubricants are 

therefore available on request from the 

major lubricating oil suppliers. 

Table III shows typical lube oils used 

on marine applications together with 

the fuel oils specified in Table I. In or- 

der to control and prevent uncontrolled 

sulphur corrosion, it has become the 

industry standard for marine engines to 

use cylinder lubricants with a BN of 70 

in combination with the average marine 

fuels, i.e. 380 cSt and 2.7% sulphur 

content. 


Special running conditions because of 

frequent bunkering of low-sulphur fuels 

and environmental fuel regulations (by 

the authorities or self imposed), requir- 

ing the use of low-sulphur fuel and spe- 

cial running conditions, might call for 

a lowering of the total alkaline additive 

content. This can be done by lowering 

the dosage towards our minimum feed 

rate or, alternatively, by using one of the 

specially designed cylinder oils with a 

lower BN and with full detergency. 

Service tests with such specially de- 

signed low-BN oils have shown good 

results. However, it may be difficult to 

determine whether changing to a BN40 

or BN50 cylinder oil will be adequate 

for operation of ultra-low sulphur fuels. 

A lower BN than 40-50 might be the 

future oil for low-sulphur operation. 

For this reason, we recommend that 

you contact MAN Diesel, or the engine 

builder, before operation on ultra-low 

sulphur fuel. 

General 

Ambient conditions Stationary engines Marine engines 

Table IV 

Maximum Average Minimum 

It should be considered that, irrespective 

of the sulphur content being high or low, 

the fuels used in low speed engines are 

usually low quality heavy fuels. 

Tropical Design 

Cooling water temp. yearly site yearly site yearly site 32°C 25°C 

Air inlet temp. climatic cond. climatic cond. climatic cond. 45°C 25°C 

Blower inlet pressure Depends on height above sea level 1000 mbar 1000 mbar

Therefore, the cylinder oils must have 

full capacity in respect of detergency 

and dispersancy, irrespective of the BN 

specified. This is a technology which 

has to be mastered by the lube oil sup- 

pliers, who can individually tailor a cyl- 

inder lube oil to the relevant fuel. 

Breaking-in cylinder lube oils for 

testbed running 

In addition to determining the optimum 

oil design for normal operation of the 

two-stroke MAN B&W engines, we 

also investigate and test various lube 

oil designs in cooperation with the oil 

companies to find the optimum cylinder 

lube oils for testbed running. 

Most builders of MAN B&W two-stroke 

engines are using low-sulphur DO fu- 

els, primarily for environmental reasons. 

This, in combination with a relatively 

high running-in lube oil dosage, re- 

quires a high detergency level in the oil. 

Therefore, we generally recommend the 

use of a BN70 cylinder oil, irrespective 

of the sulphur content of the fuel oil. 

When introducing alucoating on piston 

rings and semi-honed cylinder liners, 

we also introduced a shorter running- 

in period which, furthermore, limits the 

period in which excess cylinder lube oil 

is supplied, and improves the running- 

in conditions. This means that the en- 

tire running-in period, up to 100 hours, 

is fully acceptable for using BN70 cylin- 

der lube oils. 


Performance Verification of Cylinder 

Oils 

All oils listed have gone through a per- 

formance test for about 4,000 running 

hours on a relevant engine type in serv- 

ice and have, during the test, been in- 

spected by engineers from MAN Diesel, 

in cooperation with the oil supplier. 

When satisfactory results have been 

achieved, MAN Diesel issues a ‘Let- 

ter of No Objection’ for the use of the 

oil on MAN B&W two-stroke engines. 

However, MAN Diesel does not assume 

responsibility for any damage caused 

due to the quality of an oil mentioned in 

a ‘Letter of No Objection’. The perform- 

ance of the oil is the responsibility of the 

oil supplier. It is up to the operator to 

obtain guarantees from the oil supplier 

that the oil is suitable for operation on 

the plant in question in conjunction with 

the currently used fuel. 

If an oil on the list fails to provide ac- 

ceptable performance, then MAN 

Diesel will work together with the oil 

company to clarify the reasons and, if 

needed, have a better oil introduced. 

If an oil fails, the ‘Letter of No Objec- 

tion’ will be withdrawn. 

The list should not be considered com- 

plete, and oils from other companies 

may be equally suitable. Upon request, 

MAN Diesel will inform whether a given 

oil has been tested and whether the 

test results were acceptable. 

Further information about the oil test 

and ‘Letter of No Objection’ can be 

obtained by contacting MAN Diesel in 

Copenhagen. 

Fuels and Lubes for Stationary Twostroke 

MAN B&W Engines 

Stationary engines operate at load pat- 

terns and ambient conditions which 

differ widely from those of their marine 

counterparts. This is illustrated in Fig. 8 

and Table IV showing the typical oper- 

ating conditions for both applications. 

Thus, Fig. 8 shows that for stationary 

engines, the average load is 95-100% 

during 8,000 hours, or more, per year 

in operation, whereas for marine en- 

gines the average load is around 80% 

and, furthermore, often only for 6,000 

hours per year in operation. This means 

that stationary engines typically have a 

more than 60% higher load factor than 

marine engines. 

Stationary engines are exposed to 

widely varying ambient conditions, i.e. 

higher and lower air and cooling water 

temperatures, see Table IV. Further- 

more, stationary engines are frequently 

exposed to fuel oils of non-marine qual- 

ities. The fuel is often delivered from 

one permanent supplier, meaning that 

the quality from this supplier, good or 

bad, will prevail. 

Fig. 8: Typical load profile during a year in opera- 

tion 

% load 

110 

100 

90 

80 

70 

60 

Stationary 

Marine 

0 2,000 4,000 6,000 

8,000 

hours 

Time in service over one year 


19

Therefore, lube oils, especially cylinder 

oil, have to be individually selected and, 

at times, even individually specified and 

optimised in order to match the fuel oil 

available. 

Table III shows typical lube oils to be 

used for marine applications together 

with the fuel oils specified according to 

ISO 8217. In order to control/prevent 

sulphur corrosion, it has become the 

industry standard for marine engines to 

use cylinder lubricants with a BN of 70 

for use with the average marine fuels. 

This simple rule does not apply to sta- 

tionary engines, where the sulphur level 

in the fuel usually remains constant, i.e. 

at the level set by the supplies available, 

or, when regulated by local legislation, 

often shows a decreasing tendency 

over the lifetime of the plant. 

Hence, the constant use of a higher 

than average sulphur content, possibly 

even higher than that found in the ma- 

rine specification, will call for the use of 

a higher BN, and for this situation lube 

oils with a BN of up to 100 are avail- 

able. 

Correspondingly, long-term use of 

lower-than-average sulphur fuels will 

call for the use of lower BN lube oils, as 

described for low-sulphur marine fuels. 

In addition, the engine load for station- 

ary engines is usually very high, and the 

ambient temperature is often higher as 

well, ref. Fig. 8 and Table IV. 

Hence, temperatures are high in the 

combustion chamber, and the need to 

counteract cold corrosion with alkaline 

additives is lower, thus reducing the BN 

requirement. 


List of References 

[1] “Heavy Fuel Oil Treatment”, 

Service Letter SL05-452, 

Kjeld Aabo, MAN Diesel, 

Copenhagen, Denmark 

[2] “Marine diesel engines, catalytic 

fines and a new standard to ensure 

safe operation”, by Alfa Laval, BP 

Marine and MAN B&W Diesel 

[3] “Guidelines for the sampling of fuel 

oil for determination of compliance 

with Annex VI of MARPOL 73/78”, 

Resolution by the IMO Marine 

Environment Protection 

Committee, MEPC 96 

[4] “Operation on Low-sulphur Fuel”, 

by Kjeld Aabo, MAN Diesel, 

Copenhagen, Denmark, publication 

no.: 5510-0001-01ppr, 

January 2006 

[5] “Cylinder Lubrication Guidelines 

Operation on Fuels with Varying 

Sulphur Contents All MC/MC-C 

and ME/ME-C type engines Mk 6 

and higher, with Alpha ACC 

System”, and “Cylinder Lubrication 

New ACC Guidelines All MC/MC-C 

and ME/ME-C type engines Mk 6 

and higher, with Alpha ACC System”, 

Service Letters SL05-455 and 

SL07-479, Henrik Rolsted, MAN 

Diesel, Copenhagen, Denmark

MAN Diesel 

Teglholmsgade 41, 

2450 Copenhagen, Denmark 

Phone +45 33 85 11 00 

Fax +45 33 85 10 30 

mandiesel-cph@mandiesel.com 

www.mandiesel.com 

Copyright © MAN Diesel · Subject to modification in the interest of technical progress. · 5510-0041-01ppr Nov 2009 Printed in Denmark

Guidelines for Fuels and Lubes Purchasing - MAN Diesel & Turbo

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