Chapter 10: Final Review & Key Terms

1. Ready for Review

• The lubrication system reduces friction between moving parts in an engine and is essential for cooling, cleaning, sealing, and absorbing shock loads inside the engine.
• Lubrication systems in today’s diesels have new demands because of emissions legislation and durability requirements.
• Oil works by forming a separating film between parts, which minimizes direct contact between moving parts, reducing friction and heat buildup caused by friction.
• Oil may be derived from biological sources, but lubricating oils, even synthetics, are primarily a product of petroleum refined from crude oil.
• Engine oils are classified by the API and carry an API designation indicating their suitability for an engine application.
• Viscosity is a liquid’s resistance to flow; a numerical designation developed by the SAE is used to measure oil viscosity.
• Motor oils are typically 75–85% base stock, which is the raw mineral processed from crude oil. The remainder of the oil volume is chemical additives.
• Additives improve the original properties of the base stock oil; enhancing the performance of motor oil base stocks is necessary to adjust the performance of the oil to suit its intended application.
• Synthetic oils are oils with base stock that was synthetically derived or manufactured.
• For years, biodiesel has been considered a lubricity additive to keep moving parts operating smoothly inside fuel injection systems. However, the dilution of engine oil with biodiesel is another matter, as biodiesel promotes fuel dilution to a much greater extent than mineral diesel fuel.
• The lubrication system accomplishes its tasks as a function of a number of major lubrication system components, including pressure-regulating and pressure-relief valves, the oil pump, the oil pan, the oil cooler, and the oil filter(s).
• The function of the oil pan is to store an adequate supply of oil for the lubrication system.
• Oil pumps are used to pressurize the lubrication system of a diesel engine.
• The oil pump can produce more oil flow than the engine can use; an oil pressure-regulating valve is used to control oil pressure.
• Oil coolers are heat exchangers used to remove excess heat from engine oil.
• The purpose of lubrication oil filtration is contamination removal; oil contamination can cause abrasives to rapidly wear engine components if not properly controlled.
• Today’s diesel engine technology requires lubrication oils to meet a variety of operating conditions and provide for long service intervals and engine durability.
• The main factors that can limit oil life are the percentage of solids suspended in the oil, sulfur and combustion acids, and oxidized oil.
• Oil change intervals are based on the operating conditions an engine encounters and the amount of fuel consumed; as a general rule, every 45 gallons (170 L) of fuel consumed by the diesel engine produces enough contaminants to use up 1 quart (1 L) of oil.
• It is in the interest of owners and the environment to extend oil change intervals.
• Operation of the valves and oil pump is evaluated using a pressure gauge in the main oil gallery.

1.1. Key Terms

additives A chemical package that improves the original properties of the base stock oil.

American Petroleum Institute (API) An organization that has developed specifications to define engine oil performance standards.

anti-drainback valve A valve that prevents the oil in the engine from returning to the crankcase when the engine is shut down.

base stock The raw mineral oil processed from crude oil.

cartridge filter A filter element consisting simply of filter media unenclosed by a metal container.

dynamic viscosity A measurement of a fluid’s resistance to flow when acted upon by different bearing loads.

hot-draining Draining the oil filter at or near engine operating temperature. After the filter is removed from the engine while it is still warm, it is punctured or crushed and drained.

kinematic viscosity A measurement of a fluid’s resistance to flow while acted upon by only the forces of gravity.

multigrade oil A blend of several different oils with different viscosities; also known as multiweight oil.

oil quality sensor An electric device that measures the amount of soot loading in engine oil.

polyalphaolefin (PAO) A man-made base stock (synthetic) used in place of mineral oil. PAO molecules are smaller and more consistent in size; no impurities are found in this oil because it is derived through chemical processes.

scheduled oil sampling (SOS) An extremely detailed analysis of the condition of the engine and the quality of the engine oil.

Society of Automotive Engineers (SAE) viscosity rating An oil performance criteria that indicates an oil’s flow characteristics.

spin-on filter Filter media enclosed in a metal can that is threaded onto a filter header.

synthetic oil Oil made from base stock that is synthetically derived or manufactured.

total acid number (TAN) The acidity of an oil. Certain contaminants cause engine oil to increase in acidity, which is measured using this index.

total base number (TBN) The measurement of a lubricant’s reserve alkalinity, which aids in the control of acids formed during the combustion process.

virtual sensors Nonphysical sensors that produce data based on predictive algorithms or mathematical formulas that generate data based on other sensor inputs. An engine oil life monitor is a common example of a virtual sensor.

viscosity A measure of an oil’s resistance to flow.

viscosity index (VI) A measurement of the total amount of change in an oil’s viscosity due to temperature.

viscosity index (VI) improver An additive that prevents oil from thickening when cold and thinning when hot.