Defination: a substance (such as grease) capable of reducing friction, heat, and wear when

introduced as a film between solid surfaces. 2 : something that lessens or prevents friction or
difficulty a social lubricant.There are 4 types of lubricants: Oil, Grease,
Penetrating Lubricants, and Dry Lubricants. The 2 most common lubricants you'll be dealing
with daily are oil and grease, however, your facility will still be using dry and
penetrating lubricants.

Need for Lubrication In an I.C. engine,

moving parts rub against each other causing frictional force. Due to the frictional force, heat is
generated and the engine parts wear easily. Power is also lost due to friction, since more power is
required to drive an engine having more friction between rubbing surfaces

Lubrication System

Lubricating system is a mechanical system of lubricating internal combustion engines in which a pump
forces oil into the engine bearings.

PURPOSE OF LUBRICATION

➢ To reduce the friction between moving parts

➢ To increase the efficiency

➢ To minimize the vibrations

➢ To reduce the corrosion and carbon deposits

➢ To reduce the heat of moving parts

➢ To minimize power loss due to friction

➢ To reduce the noise created by moving parts

➢ To provide cooling to the engine

TYPES OF LUBRICANTS

➢SOLID LUBRICANTS

❑ e.g. graphite ,molybdenum ,mica

➢ SEMI-SOLID LUBRICANTS

❑ e.g. heavy greases

➢ LIQUID LUBRICANTS
❑ e.g. mineral oil obtained by refining petroleum.

PROPERTIES OF LUBRICANTS

➢ Viscosity

❑ It is a measure of the resistance to flow of an oil

❑ It is measured in saybolt universal seconds (SUS)

❑ It is expressed in centistokes ,centipoises and redwood seconds

➢ Viscosity Index

❑ viscosity of oil decreases with increase in temperature

➢ Cloud point

❑ If an oil is cooled , it will start solidifying at some time .

❑ Temperature at which oil starts solidifying , is called cloud point

➢Pour point

❑ It is temperature just above which the oil sample will not flow under

certain prescribed conditions

❑ this property is important for operation of engines and substances at

low temperature conditions

➢ Flash point and Fire point

❑ The temperature at which vapour of an oil flash when subjected to a

naked flame is called flash point

❑ Fire point is the temperature at which the oil ,it once lit with flame ,will

burnt steadily at least

for 5 seconds

➢ Specific Gravity

❑ It varies between 0.85 to 0.96

SAE Number
• Society of Automotive Engineer has recommended

SAE viscosity number for lubricating oils.

• viscosity number is determined by the range of

viscosities within it fall at the given temperature.

• For winter use 5W,10W,20W

• For normal use 20,30,40

1925-01-01

THE EFFECTS OF ENGINE OPERATION ON LUBRICATING OIL 250034

Effects of engine operation on the lubricating oil used in it determine to a large extent the ability of the
oil to maintain continuous lubrication and, consequently, of the engine to function efficiently. Engine
operation has three major effects on the oil: (a) complete destruction of part of the oil, (b) physical and
chemical changes in the oil and (c) contamination of the oil by foreign matter.

Oil is not worn out by friction but is destroyed by burning or decomposition caused by exposure to the
intense heat of fuel combustion in the cylinders or the metallic parts of the combustion-chamber. The
quantity so destroyed depends upon (a) fuel-combustion temperatures, (b) temperatures of the metallic
parts, (c) quantity of oil exposed to these temperatures, (d) length of time of such exposure, and (e)
volatility of the oil.

The quantity of oil that is exposed to the destructive temperatures, and thus consumed, depends upon
the mechanical condition of the engine, the operating conditions and the viscosity of the oil. With the
splash system of cylinder lubrication an excess of oil is supplied, some of which passes above the piston-
rings and spreads over the tops of the pistons, the combustion-chamber walls and the valve heads,
where it is constantly exposed to the flame of combustion and is destroyed. Oil on the cylinder-walls is
covered by the piston-skirts part of the time and is renewed at every piston-stroke, hence less oil
destruction occurs there. The common practice of using an oil of high viscosity to reduce leakage past
the piston-rings, thereby decreasing the oil consumption, may easily be carried too far and result in
inadequate lubrication of the upper cylinder-walls and consequent excessive wear there. With an engine
running at 1000 r.p.m., the duration of the power-stroke is approximately 1/2000 min., or 1/33 sec.,
during which brief interval only a small portion of the oil on the cylinder-walls can be destroyed.

Lubricating oil must be converted into a gas before it can burn, hence its volatility is important. The
flash-test, however, is of little value and may be misleading in determining volatility, as it does not
indicate the volatility of the entire mass. Straight-run oils composed of a narrow range of fractions from
crude petroleum and having a straight distillation-curve may show a slightly lower flash-point than a
blended oil, yet contain a smaller total quantity of the more volatile fractions than an oil having a higher
flash-point and hence will have greater ability to resist heat.
Ordinary temperature changes do not permanently alter the viscosity of an oil but the specific viscosity
is changed by relatively high temperature and by contamination. Distribution of oil to the bearing
surfaces, ability of the oil to maintain complete separation of the surfaces, internal friction or resistance
of the oil to motion and effectiveness of the oil as a piston seal are all functions of its viscosity; therefore
changes in viscosity are of importance. These are caused by gradual consumption of the lighter fractions
by oxidation and cracking and by the admixture of water, unburned fuel, carbon, dust and metallic
particles.

The excessive quantity of fuel used when starting and warming-up a cold engine is the principal cause of
dilution by fuel, water contamination is due to cold surfaces in the crankcase that condense the water
vapor of combustion, dust enters the engine through the carbureter and breather-pipe and metallic
particles wear off of the bearing surfaces most rapidly when wearing-in a new engine. Contamination by
fuel reduces the viscosity of the oil, water forms an emulsion and, with carbon, dust and metallic
particles, forms a sludge. All of these conditions are likely to have deleterious effects on the engine.

DOI: https://doi.org/10.4271/250034

Citation: WAGNER, L., "THE EFFECTS OF ENGINE OPERATION ON LUBRICATING OIL," SAE Technical Paper
250034, 1925, https://doi.org/10.4271/250034.
Download Citation

Author(s): LAWRENCE T WAGNER

Pages: 13

Event: Pre-1964 SAE Technical Papers

ISSN: 0148-7191

e-ISSN: 2688-3627

What are environmentally acceptable lubricants? 

Environmentally acceptable lubricants (EALs) are defined as a lubricant that has:

 Good biodegradability – a measure of the breakdown of a chemical (or chemical

mixture) by micro-organisms
 Low toxicity – including low toxicity to aquatic organisms
 Low bioaccumulation – build-up of chemicals within the tissues of an organism
over time.
Several countries require EALs to be used in place of mineral oil-based products in
environmentally sensitive areas, or where there is an oil-to sea interface. There are also
several interrelated classification systems for EALs including:

 European Ecolabel (LuSC list)

 United States Department of Agriculture (USDA) BioPreferred®
 Vessel General Permit legislation (VGP).
Many of our products meet the criteria for all the above classification systems, including
our industry leading range of Priolube™ ester base oils.  

Environmentally acceptable industrial gear oils 

Lubricants and fuels constitute some of the biggest losses to the marine environment,
the boundary between the oil and sea interface is under continuous scrutiny by
regulatory authorities and customers must now develop solutions that have an
acceptable environmental profile. Environmentally acceptable industrial gear oil
applications include:

 Marine thrusters
 Marine deck machinery. 
Environmentally acceptable greases
Biodegradability and renewability are vital formulation attributes in the selection of the
right grease for a given application, particularly as new and changing environmental
standards come into effect. Environmentally acceptable grease applications include: 

 Bearings
 Open gears
 Wire rope. 

Environmentally acceptable lubricants 

The properties of engine oils can affect engine emissions in a number of ways. As discussed under
Exhaust Particulate Matter, heavy hydrocarbons derived from the engine oil are a known significant
contributor to the organic fraction (OF) or organic carbon (OC) portion of diesel particulates [Voss 1995].
Engine oil hydrocarbons have also been suspected of contributing to the nucleation mode OF and,
therefore, to particle number emissions [Kittelson 2002]. Another possible contributor to particle
number emissions are high molecular mass polymers, such as viscosity modifiers, a single molecule of
which could in theory be counted as a particle by particle counting instruments.

These lube oil derived emissions are controlled through lowering the amount of oil consumed by the
engine. This can be achieved through (1) engine design and/or by (2) modifying oil properties, such as
lower volatility, better seal compatibility to minimize leakage, and better detergency/oxidative stability
to minimize cylinder deposits.

Impact of Engine Oil on Emissions and Fuel Economy

Hannu Jääskeläinen

The oil consumption from heavy-duty diesel engines meeting US EPA 2004 on-highway emission
standards can be estimated from a benchmarking study carried out on 4 heavy heavy-duty and 3 light
heavy-duty diesel engines and operated over a cycle based on the AVL 8-mode cycle [Froelund 2005].
Based on this work, the brake-specific oil consumption of these engines is estimated to vary between
0.09 to 0.45 g/kWh. This represents about 0.2% or less of fuel consumption.

For low emission diesel engines using aftertreatment, the most important emission aspect of diesel
engine oil is its compatibility with exhaust aftertreatment technologies. There are three major
mechanisms for possible interference between lube oil components and aftertreatment devices:

Accumulation of ash in particulate filters, which is a source of increased pressure drop and requires
periodic maintenance (cleaning) of the DPF.

Poisoning of catalysts by certain elements from the lube oil additive package, such as phosphorus, zinc,
or sulfur.

Formation of sulfates downstream of a catalyzed DPF or other oxidation catalysts.

Truly green lubricants are those that optimise energy efficiency and minimise wear in
the machinery which they lubricate and which have maximised service lifetimes in order
to reduce the amount of lubricant required. Increasing importance of these criteria in
lubricant selection and design is expected to lead to more widespread use of high
performance synthetic basefluids and effect additives.