Engine Lubrication System
Engine Lubrication System
Engine Lubrication System
Terminologies
Friction - is created when there is relative motion
reduce friction
Any material used is called a lubricant
Friction
1. Crankshaft friction
Components
2. Reciprocating friction
2. Connecting rod bearings, piston assembly
3. Valve train
3. Camshafts, cam followers, valve actuation mechanisms
4. Auxiliary components
4. Oil, water and fuel pumps, alternator
5. Pumping loss
5. Gas exchange system (air filter, intake, throttle, valves,
exhaust pipes, after-treatment device, muffler)
6. Engine fluid flow (coolant, oil)
ENGINE O IL
1.
PURPOSE OF
LUBRICATING
OIL parts to reduce wear.
The oil lubricates moving
Clearances between moving parts are filled
with oil. The parts move on the layers of oil.
This reduces power loss in the engine.
2. Viscosity index.
This is a measure of how much the viscosity of an oil changes
with temperature. A single-viscosity oil could be too thick at
low temperatures and very thin at high engine temperatures.
Viscosity-index (VI) improvers are added to engine oil so its
viscosity stays nearly the same, hot or cold.
3. Viscosity Numbers.
There are several grades of single-viscosity of an oil changes
with temperature. They are rated for winter of for other than
winter. Winter-grade oils are SAE 0W, SAE 5W, SAE 10W, SAE
15W, SAE 20W, and SAE 25W. The SAE stands for Society of
Automotive Engineers, which developed the grading system.
The W stands for winter. For other than winter use, singleviscosity oil grades are SAE 20, SAE 30, SAE 40, and SAE 50.
The higher the number, the
thicker the oil.
4. Multiple-Viscosity Oil.
Many engine oils have a viscosity-index
improver added. It allows the oil viscosity to
remain relatively unchanged, hot or cold. A
multiple-viscosity (multi-viscosity) oil graded
SAE 5W-30 has the viscosity of an SAE 5W oil
when cold and an SAE 30n oil when hot.
Automotive manufacturers recommend multiviscosity oil for most driving conditions.
5. Resistance to carbon formation and oil oxidation.
When oil is refined, chemicals are added to fight carbon formation
and oxidation. These can occur at the high temperatures the engine.
6. Corrosion and rust inhibitors.
Additives are put in the oil to help fight corrosion and rust in the
engine. These additives displace water from metal surfaces so oil
coats them. The additives also neutralize acids.
7. Foaming Resistance.
The churning action of the crankshaft causes the oil to foam or
aerate. This reduces the lubricating effectiveness of the oil.
Foaming can cause the oil to overflow and pass through the
crankcase-ventilating system into the intake manifold and air
cleaner. The additives help prevent foaming. A baffle in the oil
pan and a windage tray between the pan and cylinder block also
reduce foaming.
8. Detergent-Dispersants.
These additives are similar in action to soap. They loosen and
detach particles of carbon and grit from engine parts. The
circulating oil carries the particles to the oil pan.
9. Extreme-Pressure Resistance.
Additives put into the oil improve the resistance of the oil film to
penetration. Engines subject the oil to very high pressures in the
bearings and valve train. The extreme-pressure (EP) additives
react chemically with the metal surfaces. The result is a strong,
slippery film that resists penetration and being squeezed out.
1. SF OIL.
2. SG OIL.
This oil was introduced in 1989. It provides better control of
engine deposits, oil oxidation, engine wear, and rust and
corrosion than SF oil. Any older spark-ignition engine can safely
use SG oil.
Note that the service rating is an open-end series. When there
is need for oil with additional properties, SH and SI oils can be
produced.
Lubricating oil for diesel engines (C Series) must have different
properties than oil for spark-ignition engines. The CA, CB, and
CC rating are obsolete. The CD, CE, and CF ratings indicate oils
for severe operating conditions. Use the oil recommended in the
owners manual. The recommended oil may have a combined
rating, such as SG/CE or SG/CF. an oil that does not have the
recommended combined designation may cause engine
damage.
Oil-Container Labeling
The viscosity grade and service rating of an oil are different. A
high-viscosity oil is not necessarily a heavy- duty oil. Viscosity
rating refers to the thickness of the oil. This is not a measure of
heavy-duty quality. An oil with a viscosity rating of SAE 5W-30
will have a service rating of SF or SG, or a combined rating such
as SG/CF. Likewise, an oil of any other viscosity grade can have
any of the service ratings that are in use.
All oil cans and containers are marked with the API symbol (fig
24-6). It tells the type of oil and is viscosity and service ratings.
For use in a vehicle, the markings should agree with the
recommendations in the owners manual.
Lubricating System
Components
O IL
PU M P
PRESSU RE RELIEF
VALVE
O IL CO O LER
O IL FILTERS
Figures 24-2 and 24-10 show external oil filters. They attach to
the outside of the engine.
Some engines have an internal oil filter (figure 2411). It mounts inside the pan and attaches directly
to the oil pump. Removing a large drain plug allows
the filter to be changed.