This document discusses lubrication of medium speed diesel engines. It covers topics like the properties required for lubrication in internal combustion engines including bearing lubrication, piston cooling, cylinder lubrication, and cam shaft/gear lubrication. It also discusses recent engine design trends that impact lubrication like higher combustion pressures and describes how this affects properties like viscosity and detergency needed in lubricating oils. The document provides an overview of used oil analysis and how it can help identify issues like ingression of fuel or combustion byproducts into the oil from sources like leakage. It provides an example analysis of engine #1 where rises in viscosity and drops in base number indicate likely fuel ingression that could be addressed by identifying and fixing the ingress source.

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2. OVERVIEW
Medium Speed Diesel Engine Lubrication
Used Oil Analysis
2TRIBOLOGY & LUBRICATION by
SANJIV WAZIR

3. LUBRICATION OF
MEDIUM SPEED DIESEL ENGINES
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4. LUBRICATION IN
INTERNAL COMBUSTION ENGINES
 Bearing Lubrication: Adequate
Viscosity to form oil film
 Piston Cooling: Oxidation Stability
 Cylinder Lubrication: Adequate
Detergency, Dispersancy, Alkalinity,
Viscosity
 Cam Shaft/Gear Lubrication:
Adequate Anti-Wear & EP
 Fuel/Lubricating Oil
Compatibility

5. LUBE PROPERTIES REQUIRED

6. ENGINE DESIGN TRENDS
 Longer Stroke, Stroke/Bore Ratios
 Higher Combustion Pressure
 Higher BMEP
 Higher Thermal Efficiency
 Fuel Oil Quality
 Anti Bore Polish Rings
 Miller timing
 EGR,SCR,etc
 Smaller Sumps

7. IMPACT OF HIGHER
COMBUSTION PRESSURES
ON DEW POINT

8. EFFECT OF ABPR ON
OIL CONSUMPTION & WEAR
 The use of such a ring
prevents the contact
between the carbon deposits
on the piston crown and the
liner.
 These deposits often cause
liner polishing which results
in gas blow-by, risk of
scuffing and increase lube
Oil consumption.

9. OTHER ENGINE DEVELOPMENTS
PRE-PROFILING & COATING
PLATEAU HONING
ANTI BORE-POLISHING
RING

11. STRESSES ON TPEO
STRESS CAUSED BY CONSEQUENCES
THERMAL &
OXIDATIVE
STRESS
High Temperatures
causing accelerated
breakdown of lubricants
Deposits, Sludge, increased
acid generation, corrosive wear
of bearing materials, hot
corrosion of piston crown, oil
thickening, viscosity increase,
shorter oil life
ACID STRESS Acids from combustion
of S in fuels, Oxidation &
Nitration products
Corrosive wear, deposits, loss
of BN, shorter oil life
FUEL &
ASPHALTENE
STRESS
Changed nature of
residual Fuels, Higher
ingress of Asphaltenes
(raw) from fuel pump
leaks, & (burnt) from
blow-past
Deposits, lacquers, hot
corrosion, Oil thickening &
shorter oil life

12. ENG COMPONENT STRESS -
LO/ADDITIVE PROPERTY REQUIRED

13. CREATING
& MAINTAINING AN OIL FILM
Viscosity is the a
key property
SAE 30 & 40 are
mainly used
SANJIV WAZIR 13

14. MAINTAIN CLEANLINESS OF
CRANKCASE,CYLINDER LINER
& PISTON RING PACK
Detergents
Dispersants
are the key
properties
Fuel Quality Deteriorating
Fuel ingress Increasing pressures
Combustion conditions more severe
Blowby of combustion gases
Centrifuge & Fiteration
Lubricant Condition
It is estimated that a 0.4mm thick
deposit layer in Piston Underside can
cause a 100 C rise in Piston crown
temperature
SANJIV WAZIR 14

15. NEUTRALIZE SULPHURIC ACID
 Crudes contain Sulphur in varying
quantities (0 – 4%)
 Refinery processes tend to
concentrate the Sulphur in the
“bottom” residual products
 Residual Fuels can contain up to
4.5% S
 When residual fuels are burned,
the S also combusts, combining
with Oxygen from the air, forming
acidic Sulphur Oxides
 Alkalinity (BN) is the key propertySANJIV WAZIR 15

16. THE OIL IN USE
 The engine hardly ever, apart from the first start up, enjoys
unused, fresh oil
 The engine requirements are met by a combination of oil
performance reserve and the efficiency of the oil maintenance
system
 If the engine requirements are not met, undesirable
consequences can occur, such as increased LO consumption,
more frequent/unplanned oil changes, increase in fouling,
wear & tear of components, more frequent maintenance, even
engine damage & failure

17. OIL CIRCULATION &
REPLENISHMENT SPEED CONDITION

18. LUBRICATING OIL
SOURCES OF CONTAMINATION

19. MAINTAINING THE OIL CONDITION
 Maintaining the oil within acceptable limits is a function of:
1. Lube oil’s additive package reserve
2. Degree of contamination from products of combustion & other
sources
3. Excessive LO consumption due to leakage or poor engine
maintenance
4. Degree of LO cleaning by filtration & separation (centrifuging)
5. Frequency & amount of top-ups
 Extended lubricating oil life or running hours can be obtained
by optimising all these influences.

20. LUBRICATING OIL
TREATMENT SYSTEM

21. ………..TO SUMMARISE
 Larger number of product types needed to suit the wide range of
applications.
 Matching the product to the application results in the lowest overall cost.
 Improved cleanliness is essential for modern engines operating on poor
quality residual fuel.
 OEMs now prefer Higher Viscosity products
 Higher BN products are becoming more common.

23. USED OILO ANALYSIS
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24. TRIBOLOGY & LUBRICATION by
SANJIV WAZIR
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OWNER,
EQUIPMENT &
LO PARTICULARS
R.HRS OF EQPT &
OIL, SAMPLING
DATE
PHYSICAL &
CHEMICAL
PROPERTIES OF
THE SAMPLE
SPECTROMETRY
RESULTS
WEAR
METALS
CONTAMINANTS
RATING OF
CURRENT
SAMPLE
ANALYSTS
COMMENTS
SUGGESTED
ACTIONS
RESULTS OF
CURRENT
SAMPLE
PAST SAMPLE
RESULTS
TRENDING
HFO
CONSTITUENTS

25. DP ENGINE #1
HFO
CONSTITUENTS
RISING
DROPPING

26. DP PLANT
DISCUSSION
 Rise in KV and Drop in BN correlate well with the rise in
Vanadium+ Nickel (and Na), hence ingress of Bunt/Unburnt
Fuel components and Combustion by-products is likely to be
the cause.
 Soot/Insolubles levels are also up, supporting above
hypothesis
 Wear metal levels are satisfactory
 High KV could affect bearing cooling and result in temperature
rise
 Degradation of additives and ingress of combustion could
lead to increased air entrainment
TRIBOLOGY & LUBRICATION by
SANJIV WAZIR
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27. DP PLANT
SUGGESTIONS
 Source of ingress needs to be identified and rectified to
minimise oil degradation.
 Some likely source could be:
Raw Fuel: Leakage from plunger/barrel, poor injector spray
Combustion By-products: Blow-past, Mixing of Combustion
gases in T/Charger Lubrication
 Maintain the OEM recommended SLOC by regular top-up and
sweetening (if required)
 Maintain operating parameters such as Oil, Water, Air,
Exhaust temperatures and pressures within specified limits
TRIBOLOGY & LUBRICATION by
SANJIV WAZIR
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