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Motor oil is the primary determinant in the durability of an engine. It contains two basic components: base stocks and additives.
Base Stocks
The base stock is the bulk of the oil. The base stock lubricates internal moving parts, removes heat and seals piston rings. Motor oil base stocks can be made from:
- Petroleum
- Chemically synthetisized materials
- A combination of synthetics and petroleum (called para-synthetic, semi-synthetic, or synthetic blend.)
A petroleum base stock consists of many different oil fractions that form the final product. Generally, molecules of a petroleum base stock are long carbon chains that can be sensitive to the stress of heat and “boil off” at relatively low temperatures. Engine temperatures break down these molecular chains, changing the physical properties (such as viscosity) of the motor oil. The difference with synthetic base stocks is that molecules are uniformly shaped, which makes them more resistant to the stress of heat. Because AMSOIL Synthetic Motor Oils possess these uniformly shaped molecules, they have a low “boil off” rate. Thus, their physical properties (such as viscosity) do not change.
Additives
The various chemicals that comprise the additive system in motor oils function to provide anti-wear, antifoam, corrosion protection, acid neutralization, maintenance of viscosity, detergency and dispersancy. These are the chemicals that help modern motor oils meet the increasing demands of today’s high-tech engines. Their quality varies widely throughout the lubrication industry, ranging from a bare minimum in some oils (to comply with certain requirements) to exceptionally high quality, as in all AMSOIL Motor Oils.
What a Motor Oil Must Do
Modern motor oil is a highly specialized product carefully developed by engineers and chemists to perform many essential functions. A motor oil must:
• Permit easy starting
• Lubricate engine parts and prevent wear
• Reduce friction
• Protect against rust and corrosion
• Keep engine parts clean
• Minimize combustion chamber deposits
• Cool engine parts
• Seal combustion pressures
• Be non-foaming
• Aid fuel economy
Improvements in Oil
The quality of motor oil has changed dramatically in the past 30 years and new demands on lubricants in modern engine design call for oils that meet stringent requirements. Variations in an oil’s ability to meet the requirements determine which service classification rating and viscosity grade it receives. Service classifications are determined by the American Petroleum Institute. Viscosity grades of oils are determined by the Society of Automotive Engineers. These two organizations long have set industry standards for motor oils.
Viscosity
Viscosity, the most important property of an oil, refers to the oil’s resistance to flow. The viscosity of oil varies with changes in temperature – thinner when hot, thicker when cold. An oil must be able to flow at cold temperatures to lubricate internal moving parts upon starting the engine. It must also remain viscous or “thick” enough to protect an engine at high operating temperatures.
When an oil is used at a variety of temperatures, as it is in most engines, the change of viscosity with temperature variation should be as small as possible. The measure of an oil’s viscosity change is called the Viscosity Index Number; the higher the number, the smaller the viscosity change which means the better the oil protects the engine. The number does not indicate the actual viscosity in high and low temperature extremes of the oil. It represents the rate of viscosity change with temperature change.
Viscosity Improvers are viscous chemical compounds called polymers or polymeric compounds that decrease the rate at which oils change viscosity with temperature. These viscosity modifiers extend a motor oil’s operating temperature range and make multi-grade or all-season oils possible. The VI is measured by comparing the viscosity of the oil at 40°C (104°F) with its viscosity at 100°C (212°F). VI can provide insight into an oil’s ability to perform at high and low temperatures. Without this additive treatment, oils low enough in viscosity to meet the low-temperature requirements of SAE 5W or 10W motor oil will be unable to meet the high temperature viscosity requirements of SAE 30 or heavier oil. That’s because the normal rate of viscosity over the required range of ambient starting to engine operating temperatures is simply too large.
Cold Temperature Protection
Motor oil must begin to circulate as soon as the engine is started. If oil gets cold enough and begins to solidify, it fails to flow through the oil screen to the pump at engine start and causes bearings and other critical parts to fail almost immediately. Pour Point is an indicator of theability of an oil to flow at cold operating temperatures. It is the lowest temperature at which the fluid will flow. Modern refining techniques remove most of the wax from petroleum oil, but some wax-like molecules remain. These wax-like molecules are soluble at ambient temperatures above freezing, but crystallize into a honeycomb-like structure at lower temperatures and cause oil circulation problems at low temperatures. Pour Point Depressants keep wax crystals in the oil microscopically small and prevent them from joining together to form the honeycomb-like structure. They lower the temperature at which oil will pour or flow and are found in most motor oils designed for cold weather use. As synthetic motor oils do not contain those wax crystals, they do not require pour point depressant additives.
Wear Protection
Since one of an oil’s main functions is to prevent friction and wear,
Anti-wear Additives are part of the chemical composition of an oil. These additives protect engines by bonding to metal surfaces and forming a protective film layer between moving parts that are vulnerable to friction and wear when an engine is first started and before the oil begins to circulate completely. While this protective film doesn’t entirely eliminate metal to metal contact of moving parts at start up, it minimizes the effects of contact.
Oxidation
Because excessive engine heat causes chemical breakdown of oil, which in turn results in permanent thickening of the oil, oxidation inhibitors work to limit the impact of oxidation. Oil oxidation produces acidic gases and sludge in the crankcase. These gasses combine with water in the crankcase to corrode and rust the engine. Corrosion is especially critical in diesel engines.
TBN
An oil’s ability to neutralize acids is expressed by its Total Base Number (TBN). The greater the number, the greater the amount of acidic byproducts the oil can neutralize. A high TBN is particularly important in extended-drain interval oils, such as AMSOIL Motor Oils, because they neutralize acids, and more of them, for a longer period of time. Most oils for diesel engines in North America have a TBN between 8 and 12. AMSOIL manufactures several diesel oils with a TBN of 12.
Detergents
In the same way that some chemical compounds are used to prevent engine rust and corrosion, other chemicals are added to motor oil to help prevent combustion by-products from forming harmful sludge or varnish deposits. Detergents are added to motor oil because combustion causes carbon build-up and deposit formation on the pistons, rings, valves and cylinder walls. Carbon and deposits affect engine temperature, oil circulation, engine performance and fuel efficiency. Detergent additives clean these by-products from the oil. Some combustion by-products slip past the piston rings and end up in the motor oil, which can clog the engine’s oil channels.
Dispersants
While detergents help minimize the amount of combustion by-products, dispersant additives keep those byproducts suspended in a form so fine they minimize deposits. They keep the oil in the engine clean while they prevent the build-up of carbon or deposits from burned and unburned fuel and even from the oil itself. Eventually, these suspended particles are removed by the oil filter.
Foam
The addition of silicone or other compounds in very small amounts makes most oils adequately foam-resistant. It’s important to minimize foaming in motor oil because tiny air bubbles are whipped into motor oil by the action of many rapidly moving parts, resulting in a mass of oily froth that has very little ability to lubricate or aid in the cooling of the engine. These compounds weaken the air bubbles, causing them to collapse almost immediately upon forming, allowing the oil to continue to protect the engine.
Seal Swell
All motor oils must be compatible with the various seal materials used in engines. Oil must not cause seals to shrink, crack, degrade or dissolve. Ideally, oils should cause seals to expand or “swell” slightly to ensure continued proper sealing.
Heat Dispersal
Another function of motor oil is to cool the engine. The radiator/antifreeze system is responsible for about 60 percent of the engine cooling that takes place. This cools only the upper portion of the engine, including the cylinder heads, cylinder walls and valves. The other 40 percent is cooled by the oil. The oil is directed onto hot surfaces, such as the crankshaft, main and connecting rod bearings, the camshaft and its bearings, the timing gears, the pistons and many
other components in the lower portion of the engine that directly depend on the motor oil for cooling. Engine heat is created from friction of moving parts and the ignition of fuel inside the cylinder. Oil carries heat away from these hot surfaces as it flows downward and dissipates heat to the surrounding air when it reaches the crankcase. Lubricating an engine actually requires a very small amount of motor oil compared to the amount need to ensure proper cooling of these internal parts. The oil pump constantly circulates the oil to all vital areas of the
engine.
Classification Systems
Oil is classified by two systems. One system determine’s the oil’s viscosity (the SAE grade), and one determines its performance level, which oil to use in what type of engine (the API class).
SAE Grade
The Society of Automotive Engineers (SAE) Viscosity Grade is a system based on viscosity measures taken from a variety of tests. It developed 11 distinct motor oil viscosity classifications or grades: SAE 0W, SAE 5W, SAE 10W, SAE 15W, SAE 20W, SAE 25W, SAE 20, SAE 30, SAE 40, SAE 50 and SAE 60. These are single grade or single viscosity oils. These grades designate the specific ranges that the particular oil falls into. The “W” indicates the grade is suitable for use in cold temperatures. (Think of the “W” as meaning “Winter”.) The classifications increase numerically, readily indicating the difference between them and what the difference means. Simply put, the lower the number, the lower the temperature at which the oil can be used for safe and effective protection. The higher numbers reflect better protection for high heat and high load situations. SAE 20 and SAE 20W are two separate classifications. Single grade oils have a limited range of protection and, therefore, a limited number of uses. With today’s well-refined, high viscosity index oils, however, an SAE 20 oil usually will meet the viscosity requirements of SAE 20W and vice versa. Those that do are classified SAE 20W-20. This multi-grade or multi-viscosity ability increases an oil’s usefulness, because it meets the requirements of two or more classifications. Examples of multi-viscosity oils are SAE 5W-30, SAE 10W-30, SAE 15W-40 and SAE 20W-50. The number with the “W” designates the oil’s properties at low temperatures. The other number characterizes properties at high temperatures. For instance, a multi-viscosity or multi-grade oil such as 10W-30 meets the 10W criteria when cold and the 30 criteria once hot. SAE 10W-30 and SAE 5W-30 are widely used because under all but extremely hot or cold conditions, they are light enough for easy engine cranking at low temperatures and heavy enough to protect at high temperatures.
API Class
The American Petroleum Institute (API) developed a classification system to identify oils formulated to meet the operating requirements of various engines. The API system has two general categories: S-series and C-series. The S-series service classification emphasizes oil properties critical to gasoline or propane fueled engines. If an oil passes a series of tests in specific engines (API Sequence tests), the oil can be sold bearing the applicable API service classification. The classifications progress alphabetically as the level of lubricant performance increases. Each classification replaces those before it. SL oil may be used in any engine, unless the engine manufacturer specifies a “non-detergent” oil. SA and SB are non-detergent oils and are not recommended for use unless specified. New car warranties from 1980 to 1989 require SF oils, while new car warranties from 1990 to 1993 require SG oils. New car warranties beginning with the 1994 model year require oils with an API SH performance rating. Beginning with 1997, new car warranties require and API SJ oil. The year 2001 brought the introduction of SL oils. SL oils are designed to increase fuel economy, reduce emissions and protect hot, hard-working engines over the course of a very long warranty period. C-series classifications pertain to diesel engines. They are: CA, CB, CC, CD, CD-II, CE, CF, CF-II, CF-4, CG-4, CH-4 and CI-4. All are obsolete except CF, CF-II, CH-4, and the new CI-4 performance rated oils. However, oils used in turbocharged gasoline engines retain CF as part of their performance designation: SH, CF. Unlike S-series classifications, C-series classifications do not supersede one another. The current classifications, CF, CF-2, CH-4 and CI-4 are specified for various applications. CF for Indirect Injected Diesel Engine Service. Service Category CF denotes service typical of indirect injected diesel engines and other diesel engines that use a broad range of diesel fuels in off-road applications, including diesel fuel with greater than 0.5 percent sulfur by weight. CF oils may be used in place of CD oils. CF-2 for Two-Stroke Diesel Engine Service. This service category is typical of two-stroke engines requiring highly effective control over cylinder and ring-face scuffing and deposits. CF-2 oils may be used in engines for which CD-II oils are recommended. CI-4 for Severe Duty Diesel Engine Service. CG-4 typically is required in high speed four-stroke diesel engines used in heavy-duty on- and off-highway applications. CI-4 oils are especially effective in engines designed to meet 2000 exhaust emission standards. CI-4 oils may be used in place of CD, CE, CF-4, CG-4 and CH-4 oils. These classification systems aim to help motorists choose the right oil for their needs. The choice depends on the engine, the outdoor temperature and the type of driving the engine must withstand. SJ and SL are the current API class. SJ and SL oils are widely available and ensure the best engine protection available.
How Motor Oil Becomes Contaminated
Motor oil becomes unfit for service after a period of use. Two main reasons for this are the accumulation of contaminants in the oil and chemical changes (additive depletion and oxidation) in the oil itself. These factors cause deterioration of the oil and prevent it from doing the job of lubricating and cooling engine parts.
Abrasives
Road Dust and Dirt
Design limitations of air cleaners, some oil fill caps, and crankcase ventilation systems unfortunately allow some dust and dirt to enter the engine. Leaks in the intake system also permit unfiltered air to enter the engine. However, proper maintenance of the engine and its accessories can minimize the amount of contaminants entering the lubrication system and extend engine life.
Metal Particles
Normal wear of parts in an engine produces very small metal particles that are picked up and circulated by the oil. Particles of road dust and dirt increase the rate of wear and generate larger metal particles, that in turn are quite abrasive. These, too, are circulated through the engine by the oil. While oil filters help keep these particles at a minimum, they can’t remove them entirely.
Combustion By-products
Water
Combustion produces water vapor, or steam. When engine temperatures are high, most of the water remains in vapor form and goes out through the exhaust. However, when engine temperatures are low, such as at start-up, warm-up and short trip operation in low ambient temperatures, the water vapor condenses (turns into a liquid) on cylinder walls and is picked up in the crankcase oil. Here it leads to the formation of sludge, rust and corrosion.
Acids
The combustion process produces acidic gases which, like water vapor, condense on cylinder walls at cold engine temperatures and also find their way into the crankcase oil. These combine with water to cause rust and corrosion.
Soot and Carbon
Incomplete combustion produces soot, carbon and other deposit-forming materials. An engine running too “rich,” or with too much fuel, increases the amount of contaminants. In gasoline engines, light-load and low-speed operations increase these combustion by-products more than high-load, high-speed operations. Diesel engines produce more of the by-products with lowspeed, high-load operations.
Dilution
When and engine is started or running abnormally, some unburned fuel in liquid form is deposited on cylinder walls. That means raw fuel leaks past the rings into the crankcase, where it reduces the viscosity of the oil. Dilution lowers the film strength of the oil and increases oil consumption. Usually this is a minor problem when engine operation is at high-speed, high-temperatures, but it can be a problem in vehicles consistently used for short trip driving. While all of the processes by
which a motor oil is contaminated are not fully defined, the use of high quality motor oils such as AMSOIL Synthetic Motor Oils, which allow motorists continued protection of their engines along with extended drain intervals limit the contaminants in the oil and prolong engine life.
Engine Wear
Automotive experts agree dirt is the number one cause of engine wear. Analysis by Federal-Mogul Corporation reports that 43.4 percent of all engine bearing distress is caused by dirt. Engine dirt particles are so small – mere dust specks – and an engine is a highly sophisticated piece of machinery, crafted from the most durable metal alloys. How, then, can these minute particles bring down such a high-tech giant? The answer lies in the fact that dirt particles are extremely abrasive. They consist of razor-like flakes of road dust and airborne grit drawn into the engine through the intake manifold. as well as manufacturing scarf and wear metal particles generated inside the engine. These particles are carried by the oil into the precision clearances between bearings and other moving parts. Once they work in between these parts, they grind and gouge surfaces, altering clearances and generating more abrasive debris. This wear cycle continues, making precision components sloppy and fatigued until they fail altogether. Filtration is the key to preventing costly engine repairs caused by dirt. Filtration removes contaminants by trapping and holding them outside the system of oil circulation. In order for a filter to be truly effective, it must be able to capture contaminants of all types and sizes. AMSOIL has developed a complete line of sophisticated filtration products designed to offer the best protection available against virtually all harmful engine contaminants.
Air Filtration
An engine “breathes” air to mix with fuel for combustion – about 9,000 gallons of air for every gallon of gas. All that air contains more than 400 tons of suspended dirt in one cubic mile over a typical city, and the concentration is much higher in rural areas where travel frequently is over unpaved roads. The air filter is the first line of defense against the abrasive airborne grit that gets into an engine. In order to do the job right, the air filter must effectively filter the dangerous
particles without obstructing the vital flow of air that sustains the engine. Conventional air filters use pleated paper as the filter media. These paper surfaces quickly become obstructed with dirt, reducing vital engine air intake, leading to poor engine performance and low fuel efficiency. They require frequent replacement.
AMSOIL Filters Last Indefinitely
AMSOIL uses thick layers of polyurethane foam in its 2-Stage Air Filter construction. This foam is wetted with a light coating of “tack” oil. As air is drawn through the honeycomb network of oiled fibers, dirt particles are trapped by the oil and only clean air emerges from the foam and passes into the engine. AMSOIL 2-Stage Foam Air Filters are designed to last indefinitely with proper service. Under normal driving conditions they may be used for 25,000 miles or one year, then cleaned, re-oiled, reinstalled and used again for thousands of additional miles of trouble-free service.
Oil Filtration
Full-flow oil filters install directly into the line of oil circulation. The “full-flow” of oil passes through the filter as the oil journeys between the oil pump and the engine. A full-flow filter must be able to remove and hold contaminants without obstructing oil flow to the engine. Most filters on the market compromise the filtration of finer particles by using a thin layer of porous filter paper. These filters have almost no extended cleaning ability since they have a low capacity for storing
dirt. These “surface-type” paper filters quickly become restricted as debris builds up on the paper surface. When this happens, the filter by-pass valve opens and allows unfiltered oil into the engine. The AMSOIL SDF Engine Oil Filter is composed of a special cellulose, synthetic and glass blend media to provide longer life and improved efficiency. Performance tests demonstrate that AMSOIL SDF Filters provide up to 100 percent more capacity than other leading filters. They also achieve nearly 95 percent operating efficiency, outperforming all major brands. An oil pressure relief valve assures proper oil flow at all times under all operating conditions. Each heavy-duty case has a drawn steel doublecrimp at the base with rolled-under seaming. An anti-drain back valve keeps dirty oil in the filter when the engine is not running.
By-Pass Oil Filtration
An average full flow filter traps particles as small as 20 microns. The filter can’t remove finer particles because the oil must be filtered quickly while removing most of the particles in the oil. However, particles in the 5 to 20 micron range cause up to 60 percent of all engine wear. Not only does the AMSOIL By-Pass Oil Filter trap particles in the 5 to 20 micron range, it traps particles significantly smaller. Unlike the full-flow filter, a by-pass filter is attached outside the main line of oil circulation. The by-pass filter taps into the main line, bleeding off and cleaning only a portion of the oil at any one time. It retains the oil longer and does a thorough job of removing contaminants without the worry of obstructing oil circulation. Because the AMSOIL By-Pass Filter traps even the smallest of particles, it leaves oil analytically clean and free from harmful dirt particles. Although the AMSOIL By-Pass Filter draws only about 10 percent of the oil in the system at one time, it will filter all the oil in a six-quart system in about five minutes at an engine speed equivalent to 45 miles per hour.
Water Removal
As discussed earlier, engines accumulate water from intake air and fuel combustion. Water promotes rust and corrosion in engines. It also reacts with oil additives to reduce additive effectiveness. Water is particularly harmful in cars that are not driven often. The unique composition of the AMSOIL By-Pass filtering media allows the removal of water from engine oil. Even water that has been thoroughly churned into the oil by mechanical agitation is separated and safely stored in the cartridge, or filter element, eliminating the risk of oil degradation and engine rust and corrosion.
Reduces Oil Changes
By cleaning the oil so completely, the AMSOIL By-Pass Oil Filter not only prolongs engine life but also the life of the oil itself. With the AMSOIL By-Pass Oil Filter, oil changes can be extended well beyond normal, in many cases virtually indefinitely, depending upon the conditions and severity of use.
Dual Remote: Patented Protection
Available only from AMSOIL, the Dual Remote Oil Filtration System replaces conventional full flow filters, mounting in any convenient location in the engine, and gives full flow and by-pass oil filter protection. With Dual Remote, filter changes are quick, clean and
easy. It also increases an engine’s oil capacity, helping oil work better, not harder.
Oil Analysis
By analyzing used engine oil, a qualified lab can determine the degree of protection the oil is delivering and make certain the oil has not been contaminated. Oil analysis also can detect impending engine
failure. The AMSOIL TRIGARD Plan offers motorists AMSOIL Synthetic Motor Oil, AMSOIL Oil and Air Filters and oil analysis for their personal use vehicles. The AMSOIL G-1318 and G-1451 offer oil analysis for heavy duty diesel engines in commercial use. They also may be used for passenger car oil analysis. Oil analysis helps motorists derive the longest life from their AMSOIL Synthetic Motor Oil and from their engines.
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