VISCOSITY AND THERMAL PROPERTIES OF TWO BRANDS OF MOTOR OIL BSC ECT001

VISCOSITY AND THERMAL PROPERTIES OF TWO BRANDS OF MOTOR OIL

 

A RESEARCH PROJECT

 

DEPARTMENT OF PHYSICS

ELECTRONICS AND COMPUTER TECHNOLOGY UNIT

FACULTY OF SCIENCE

UNIVERSITY OF CALABAR,

PMB 1115, CALABAR, NIGERIA.

 

 

IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE AWARD OF BACHELOR OF SCIENCE (B.SC.) DEGREE IN ELECTRONICS AND COMPUTER TECHNOLOGY

 

 

 

MAY, 2014

ABSTRACT

            The viscosity and thermal properties of two brands of motor oil, involves the measurement and analysis of oando motor oil and pennzoil motor oil. This is done using dynamic viscosity test which measures how viscous or how fluid an oil is and also kinematic viscosity test which measures the density and calorimeter for thermal properties.

TABLE OF CONTENTS

Title page     -           -           -           -           -           -           -           i

Certification            -           -           -           -           -           -           -           ii

Dedication   -           -           -           -           -           -           -           iii

Acknowledgement           -           -           -           -           -           -           iv

Abstract       -           -           -           -           -           -           -           -           vi

Table of contents -           -           -           -           -           -           vii

CHAPTER ONE           

1.1      Introduction            -           -           -           -           -           -           1

1.2      Basic Principle of Lubrication     -           -           -           3

1.3      Thermal Degradation       -           -           -           -           7

1.4      Corrosion     -           -           -           -           -           -           8

1.5      Shearing       -           -           -           -           -           -           -           10

1.6      Contamination       -           -           -           -           -           12

CHAPTER TWO

2.1      Viscosity of Oil       -           -           -           -           -           15

2.1.1   Viscosity Index Improver            -           -           -           18

2.1.2  Viscosity Grades    -           -           -           -           -           21

2.3      Motor Oil SAE  Viscosity Classification          -           26      

CHAPTER THREE 

3.1      Motor Oil     -           -           -           -           -           -           -           29

3.2      Types of Motor Oil            -           -           -           -           -           30

3.3      Motor Oil Refining Process        -           -           -           32

3.4      Complex Blended Oil Additive  -           -           -           35

CHAPTER FOUR     

4.1      Motor Oil Viscosity Testing       -           -           -           37

4.2      Concerting to Synthetic Motor Oil      -           -           45

CHAPTER FIVE

5.1      Summary     -           -           -           -           -           -           48

5.2      Conclusion   -           -           -           -           -           -           48

            References  -           -           -           -           -           -             50

CHAPTER ONE

1.1      Introduction   

            One of the largest applications for lubricant, in the form of motor oil, is protecting internal combustion engines. Using the correct motor oil with its appropriate viscosity and thermal properties helps motor engines run smoothly. Primarily, oil stops the metal surfaces in engines from grinding together and wearing by creating a separating oil film between them.

The oil also disperses heat and reduces wear thereby protecting the engine. On top of this, good oil with adequate viscosity and thermal properties prevents dirt build up and deposits by keeping them in suspension. Motor oil even protects against sludge and fights oxidation, keeping the oil fresh and minimizing acids which can cause corrosion in a short time.

            Viscosity is a measure of a “flowability” of an oil. Specifically it is the property of an oil to develop and maintain a certain amount of sheering stress dependent on flow and then to offer continuous flow. (Hackett, 1999). Thicker oil generally have higher viscosity, and thinner oils a lower viscosity; this is the most important property for motor engine oils. An oil with too low viscosity can shear and loose film strength at high temperatures while an oil with too high a viscosity may not pump to the proper parts at low temperatures and film may tear at high temperature.

The weight given amount are arbitrary numbers assigned by the society of automotive engineers (S.A.E). These numbers correspond to “real” viscosity as measured by several accepted techniques and these measurement are taken at specific temperatures.           

            Typically, motor viscosity and their thermal properties are interesting in terms of how they influence the return of the lubricant to the compressor.

Furthermore, when hearing the word “viscosity” the thicker a liquid, the higher the viscosity why the lower the viscosity the thinner the liquid. While the definition also applies to oil, the system uses labels. The viscosity of Passanger Car Oil (PCEO) is one of the least understood automotive specifications. The lower the heat transfer fluids viscosity, the less the energy that would be required to pump it through the system.

1.2      Basic Principle of Lubricant 

            Before a proper lubricant is selected for a specific application some basic theory must be understood. When one surface moves over another there is always some degree of resistance to movement called friction. Friction can manifest it self in varying degrees from smooth easy sliding to uneven erratic movement, which can generate excessive heat and cause damage to moving surfaces.

            Friction is good when it causes the brakes and tries on cars and tracks to stop the vehicle or when it keeps our shoes from slipping on wet surfaces, yet friction is bad when it causes heat, wears and reduces energy in an engine or gearbox.

            Lubrication is simply the use of a material to improve the smoothness of movement by reducing friction. The immediate result is reduced wear and reduced heat generation. There are numerous types of lubricants but for this project the main consideration is synthetic and petroleum motor oils.

The needed force to start the movement is defined as static friction and is typically always greater that the dynamic friction, which is the force required to keep the two materials moving at the same speed once initial movement has started, Dave (2008). Different oils and different materials loading condition can create vastly different coefficients of friction that can affect performance and longevity of an engine and other mechanical components.

A few basic key functions of a motor oil is to reduce friction under all extremes of operating condition, prevent corrosion of internal engine components and provide cooling via transfer of heat.

            When it comes to reduction of friction (as well as preventing corrosion and providing effective heat transfer), for example when using a petroleum oil, under certain conditions, the lubricant film can be either too thin, thus allowing metal-to-metal contact or too viscous which causes high internal friction within the layers of the oil. The key is to select an oil grade that is thin enough to have low internal friction coefficient, yet still high enough to effectively separate two metal surfaces under all operational conditions and prevent excessive wear and heat generation.

The fact proves that synthetic oil because of its good film allows the oil to flow freely for low internal friction, yet still effectively separate metal-to-metal contact surfaces under normal and extreme operating condition and significantly reduce internal wear.

When looking at metal surfaces, such as piston to cylinder, and it is visually seen that they appear smooth, this does not accurately reflect reality until when viewed under a high powered microscope. The smoothest machined surfaces are rough and are viewed as million of peaks and valleys.

These peaks are under extremely high loading and need to wear in (commonly called break-in) on a new engine.

However, there is much discrepancy among automotive and motorsports enthusiast as to how the length of time required for engine wear-in and whether or not petroleum oil must be used for the initial wear-in. (Oscar, 1950).

1.3      Thermal Degradation  

            Whenever a motor oil is heated beyond a certain temperature, it will start to degrade, even if there is no oxygen present. This is called thermal degradation and causes the oil to change viscosity. (Marthin, 2004). The thermal stability of a motor oil cannot be improved by use of additives but it can be improved by refining out the same compounds that decrease the oxidation resistance. As temperature increases, thermal degradation increases. In order for oil to provide proper service protection at high operating temperature, highly refined oils with plenty of anti-oxidant should be used. There is also a direct correlation between price of a particular oil and it’s performance under temperature extremes, less costly oils are generally refined less and have a lower capability to prevent/reduce thermal degradation.

Petroleum oil has a lower thermal property operating temperature range while premium quality synthetic motor oil brands have a very high operating temperature range and are much more resistant to thermal degradation.

1.4      Corrosion    

            Petroleum oil that is new or kept clean by proper filtration is generally non-corrosive and will provide good protection against corrosion caused by the atmosphere. However, inside an engine oil oxidation by-products will attack internal engine steel and bearing materials that are typically manufactured aluminum, copper, lead and tin (a Lead Tin Flashing is used for break-in purpose on the few engines that use aluminum rod and main bearing). Most gasoline and diesel engines use copper lead main and connecting rod bearings.

            The water present due to condensation caused by temperature and humidity changes or short stop and driving where the engine never reaches the proper operating temperature, although still hotter then the ambient temperature, can also cause corrosion. The hotter the oil when water is present, the more the chemical reaction is and corrosion related damage could definitely occur. In addition, water present in an oil for an extended period of time can emulsify the oil and form a mixture which is much more corrosive than the two components alone and can then form a sluge which may block oil filter or small passages. It is critical to operate an engine at normal operating temperature to prevent as well as burn off any water that is present by an evaporation process. The most severe type of driving an oil can be subjected to (as well as an internal components) is short drives and intermittent operation in which the engine and oil never have time to reach normal operating temperatures for an extended period of time.

A quality motor oil will have a corrosion inhibitor added. Corrosion inhibitors also vary in terms of effectiveness, quality and quantity.

1.5      Shearing            

            The word “oil breaking”, is used by many people to represent what they think is a motor oil that is “broken down” and is in need of changing, when in reality the actual process of “break down” is not properly understood. The correct word for this is oil break down due to shear forces. An internal combustion engine imparts high shear forces on a motor oil, which is mixed between two rotating sliding forces under load and heat. The molecular structure is essentially torn apart by these mechanical shear forces. The component of the oil affected most by these shear forces is the viscosity improver.

These viscosity improvers allow the manufacturer of the oil to create multi-grade oils suitable for a wider temperature range of operation. The end result of these shear forces is a decrease in the viscosity of the oil as well as a decrease in the viscosity index. Once a motor oil has sheared beyond a specific point it will not revert back to it is base structure when it cools down and the shear forces have ceased. This does not affect synthetic oil because synthetic motor oils are extremely resistant to the detrimental effects of shear forces.

            This phenomenon can be explained thus: A look at the molecular structure of motor oil under a microscope we see chains of molecules grouped together and linked together. The smaller molecular particles are attached to the larger ones. As an oil shears these smaller molecules break away and align in the chain. As engine heat and shear forces continue and increase these molecules break away from the base structure and in the process provide less and less resistance to wear. If this shearing continues over an extended period of time engine damage can occur. If shearing is not much then when the oil cools down the structure will be never back to its original structure and still be capable of providing proper engine protection. (Khomenko, 2007).           

1.6      Contamination

            Contamination of motor oil causes deterioration of the oil. Some of the more common contaminant sources include dirt, sand and dust from the air, soot, unburned fuel in the oil, water from condensation of the combustion process, wear, metal particulates that oil filter cannot trap and hold, corrosion by-products and additive elements that have degraded. A combination of dirt, sand and dust can continue to enter the engine and, in addition to creating more wear, combine with other contaminants and cause more damage than they would separately.

            One of the many by-products of combustion is soot.  Soot can be highly abrasive as well as cause filters to become filled and/or plugged in extreme cases. Another contaminant is acidic by-product of combustion, which can produce highly corrosive mixture and cause corrosion and pitting of internal engine component and additional generation of wear debris. These same acidic solutions can also mix with water inside the engine and form an emulsion that can cause problems with oil filters and passageways.

            Yet another source of contamination is fuel. A charge of fuel is rarely 100% burned during the combustion process. This unburned fuel can mix with the oil present in the cylinders.

Fuel contamination can also be caused by worn sealing components such as excessive piston ring to cylinder clearances allowing unburned fuel to blow-by the rings. When a motor oil is diluted with fuel the effect is that the viscosity is lowered. If this reaches extremes of contamination excessive wear and engine damage can take place. Operating an engine not sufficiently warned up can also increase combustion, blow-by. It is much better to let your engine sufficiently warm up before driving away which can have a significant effect on preventing fuel blow by as well as producing a much more efficient combustion cycle.

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