OILS

The composition, functions, additives, types and certifying bodies of lubricating oils.

​Machinery like our automobiles relies on lubrication to keep the moving parts from wearing out quickly. Lubricating oil is processed from crude oil in a refinery, along with gasoline and diesel as well as with many other beneficial and useful products. Oil is much more than simply crude oil dumped into our engine’s crankcase; it is heavily processed to remove impurities, and many additives are put into the processed oil to enhance its lubricating qualities.

Each moving part in the engine needs lubricating oil. The system that moves the oil through the engine is called the lubrication system. This chapter covers the theory and components of lubrication systems. It provides a solid foundation for the next chapter, which is where we discuss servicing the lubrication system and its components.

​ A customer comes in needing a tire patched on his vehicle. When the vehicle is brought into the shop, an inspection is performed, and the oil doesn’t read on the dipstick. The customer tells you that her friend added two quarts to it when he borrowed it last week, and that it regularly needs that much or more oil. She says that she hasn’t been concerned about the level of the oil because the oil light is not on. She wants to know why the oil light didn’t come on and what oil does that is so important. How would you answer her following questions?

​You Are The Technician.

Open Ended

What functions does the oil perform inside an engine?

Open Ended

Why didn’t the oil pressure light indicate that the oil was below the “add” line?

Open Ended

What is viscosity?

Open Ended

What does “W” stand for in 5W30 oil?

Oil originates from the ground as crude oil . Crude oil varies in color from a dirty yellow to dark brown, to black. It can be thin like gasoline or a thick oil- or tarlike substance. Crude oil is pumped from the ground and processed into many products such as fuel for use in diesel and gasoline vehicles. Crude oil is also broken down into other products, which are used in plastics manufacturing as well as in kerosene, aviation fuel, asphalt, cosmetics, pharmaceuticals, and many other products. Many of the products refined from crude oil are used in the transportation industry.

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​ For example,
lubricating oil is distilled from the crude oil and used as a base stock. Additives are added to the base stock to make the lubricating oil useful in engines. Other additives, such as thickening agents, are added to the base stocks and used as lubricating grease in bearings. The additives that are added to the base stock perform a variety of tasks such as keeping acids from forming, cutting down on oxidation, and maintaining the correct viscosity over a broader temperature range. We cover those qualities in more depth later.

​Functions of Lubricating Oil

​ Lubricating oil performs five main functions: lubricates, cushions, cools, cleans, and seals. Lubrication involves reducing friction, protecting against corrosion, and preventing metal-to-metal contact between the moving surfaces. Friction occurs between all surfaces that come into contact with each other. When moving surfaces come together, friction tends to slow them down. Friction can be useful, as in a brake system. In the moving parts of engines, friction is a bad thing and will lead to serious damage. Friction can make metal parts so hot they melt and fuse together. When this happens, an engine is said to have seized and will need to be rebuilt or replaced.

Lubrication reduces unwanted friction as well as wear on moving parts. Clearances, such as those between the crankshaft journal and crankshaft bearing, fill with lubricating oil so that engine parts move or float on layers of oil instead of directly on each other .. By reducing friction, less power is needed to move these components, and more of the engine’s power can be used to turn the crankshaft instead of wasted as heat; the result is increased power to move the vehicle and better fuel economy.

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​ How long an engine lasts depends mostly on how well it is lubricated, especially at the points of extreme loading, or high-wear areas, such as between the cam lobe and cam follower. At the same time, the connecting rod and crankshaft bearings take large amounts of stress as the piston transfers thousands of pounds of force to the crankshaft each time the cylinder fires. The lubricating oil between the surfaces helps to cushion these shock loads, similar to the way a shock absorber absorbs a bump in the road.

Lubricating oil also helps cool an engine. The lubricating oil collects heat from the engine’s components and then returns to the oil pan, where it cools. The heat from the lubricating oil is picked up by the air moving over the oil pan. Many heavy-duty and high-performance vehicles have cooling fins on their oil pan or even a separate oil cooler to extract more heat from the oil, which helps the oil do an even better job of cooling critical engine components . When inspecting an engine for leaks, don’t forget to check the oil cooler, if equipped.

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​Lubricating oil also works as a cleaning agent. There are additives in the lubricating oil that allow it to collect particles of metal and carbon and carry them back to the oil pan. Larger pieces fall to the bottom of the oil pan while smaller pieces are suspended in the oil and are removed when the oil moves through the oil filter. When oil is changed, most of the particles are removed with the oil filter and old oil. The last function of oil is that it seals. It plays a key role in sealing the piston rings to the cylinder walls. Without a small film of oil between the rings and cylinder walls, blowby gases would be much higher, resulting in diluted oil, lower compression, lower power, and lower fuel economy. Knowing the five functions of oil will allow you to better diagnose and maintain customer’s vehicles, so remember them as we explore how the system works, as well as each component.

​Viscosity

​For oil to be able to cushion parts, it needs to have the proper viscosity. Viscosity is a measure of how easily a liquid flows. Low-viscosity liquid is thin and flows easily. High-viscosity liquid is thick and flows slowly. Lubricating oil must be thin enough to circulate easily between moving parts, but not so thin that it will be squeezed out easily. If it is too viscous, it moves too slowly to get to the moving parts, especially in a cold engine. As engine machining and metal technology have become more advanced, the clearances between lubricated parts have decreased. As a result, engine manufacturers have specified thinner oils for their engines so that oil can flow into the smaller clearances. The thinner oil also flows more easily, which reduces drag and increases fuel economy.

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Oil Additives

​Special chemicals called additives are added to the base oil by the oil companies. Different combinations of these additives allow the oil to perform the different functions in an engine. A description of common additives follows:

​Extreme-pressure additives coat parts with a protective layer so that the oil resists being forced out under heavy load. This improves the cushioning effect.
Oxidation inhibitors stop very hot oil from combining with oxygen in the air to produce a sticky tarlike material that coats parts and clogs the oil galleries and drain-back passages. Oil galleries are the passageways that carry oil through the engine. They are either cast or drilled into the engine block and head(s).
Corrosion inhibitors help stop acids from forming that cause corrosion, especially on bearing surfaces. Corrosion due to acid etches into bearing surfaces and causes premature wear of the bearings.
Antifoaming agents reduce the effect of oil churning in the crankcase and minimize foaming. Foaming allows air bubbles to form in the engine oil, reducing the lubricating quality of oil and contributing to breakdown of the oil due to oxidation. Because air is compressible, oil with foam reduces the ability of the oil to keep the moving parts separated, causing more wear and friction.

​Detergents reduce carbon deposits on parts such as piston rings and valves. Dispersants collect particles that can block the system, separate them from each other, and keep them moving. They will be removed when the oil and filter are changed Pour point depressants keep oil from forming wax particles under cold temperature operation. When wax crystals form, they result in the gelling of the oil and keep oil from flowing during cold start-up conditions. Gelling is the thickening of oil to a point that it will not flow through the engine; it becomes close to a solid in extreme cold temperatures.

​As stated above, one of the functions of lubrication is corrosion protection. Acids build up in the engine due to the accumulation of combustion byproducts and moisture. Blowby gases contain chemicals that are trapped in the oil. The chemicals react and form acids. When the engine is turned off, it begins to cool. The cooling process creates moisture that then condenses into droplets that fall into the oil and form acids. The acids attack the internal components, causing unnecessary damage. The oil contains anticorrosion additives that coat the engine surfaces, helping to protect them from the effects of the acids and water.

Types of Oil

​Conventional oil is processed from crude oil pumped from the ground . The crude oil contains many impurities that are removed during the refining process. One of the impurities found in all crude oil is wax. This wax is removed during refining and is used for candle wax; it also serves as an additive in some food and candy. Wax is not a good thing in oil because it creates a thickening effect when it gets cold, becoming too thick to flow through the engine. Crude is broken down into mineral oil, which is then combined with additives to enhance the lubricating qualities. Without the additives, conventional oil would not work well. It would foam easily, break down quickly, and corrode the engine parts after being in the engine for a short time.

​Synthetic Oil

There are two main categories of synthetic lubricating oils: type 3, which is nota true synthetic, and type 4 (PAO), which is a true synthetic oil. Both types of synthetics are more costly to manufacture, as the base stocks are more highly refined or are developed in a lab and are therefore more costly. Conventional oil is processed from crude oil pumped from the ground. customer. Synthetic lubricants have a number of advantages over conventional oils. They offer better protection against engine wear and can operate at the higher temperatures needed by performance engines. Synthetic oils have better low temperature viscosity, which allows the oil to be circulated through the engine more quickly during low temperature engine start-ups. Synthetics have fewer wax impurities that coagulate at low temperatures, they are chemically more stable, and they are generally thinner so they allow for closer tolerances in engine components without loss of lubrication. Modern high, performance engines run much tighter tolerances, so the need for a thinner oil that is able to hold up under higher temperatures is desirable. Some synthetics also last considerably longer, extending oil change intervals to 20,000 miles (30,000 km) or more, which benefits the environment by reducing the used oil stream and reducing the need for finding new sources of oil.

​True synthetic oils are based on artificially made hydrocarbons, commonly polyalphaolefin (PAO) oil, which is a artificially made oil base stock—meaning it is not refined from crude oil. Synthetic oils were developed in Germany during World War II due to the lack of crude oil. Synthetic oil was used primarily in jet engines because of the high heat demands of these engines. Normal conventional oil would create heavy carbon deposits on bearings due to the extreme heat, which led to failures. Amsoil was the first synthetic to be approved by the API in 1972. Many companies now offer synthetic oils. Very few synthetic oils on the market are full PAO oils. Many of the oils allowed to be labeled as synthetic are in fact blends of processed mineral oil (highly refined base stock refined from crude oil) and PAO, or even just highly refined base stock, that possess lubrication qualities similar to PAOs.

Multiple Choice

Amsoil was the first synthetic to be approved by the API.

• True

• False

Multiple Choice

Viscosity is a measure of how easily a liquid flows.

• True

• False

Open Ended

Lubricating oil performs five main functions: what are they?

Multiple Choice

One of the impurities found in all crude oil is wax

• True

• False

​Synthetic Blends

Synthetic blends give some of the benefit of the full synthetic with the cost effectiveness of conventional oil. These oils are a mix of conventional high, quality oil and full synthetic oil. They need to be changed sooner than a full synthetic but less frequently than conventional oil. The purer the base stock is after the refinement process, the longer the oil will last in the engine. Some manufacturers are now recommending synthetic blend oil over conventional oil due to the better protection and performance of these types of oils. Because it is half synthetic, half conventional, the full benefit of the thinner, higher performance pure synthetic is diluted, but in turn the conventional half is improved by adding oil that has no impurities.

Oil-Certifying Bodies and Their Rating Standards

​ There are several certifying bodies for engine oil, each with its own standards. The three most common are the American Petroleum Institute (API), the American Society of Automotive Engineers (SAE), and the International Lubricant Standardization and Approval Committee (ILSAC). However, there are three others that technicians must be aware of: the Japanese Automotive Standards Organization (JASO); the Association des Constructeurs Européens d’Automobiles (ACEA), also called the European Automobile Manufacturers Association; and the original equipment manufacturers’ (OEM) own standards. Let’s look at them one at a time.

​American Petroleum Institute (API)

​The API sets minimum performance standards for lubricants, including engine oils. The API has a two-part classification: service class and service standard. The API service class has two general classifications: S for spark ignition engines and C for compression ignition engines, also referred to as “commercial.” Engine oil that meets the API standards may display the API service symbol, which is also known as the API “donut.” This protocol is important to understand because S-rated oil cannot be used in compression ignition engines unless they also carry the appropriate C rating, and vice versa. Be careful that the wrong oil is not used in a particular engine.

​ The API service standard (SA) was used in engines up until 1930, which means pure mineral oil without any additives. As engine manufacturers improved engine technology—or as government regulations changed, such as requiring reduced amounts of phosphorus—engine oil with new qualities was required, and the API would introduce a new rating level. The API SN level was added in October 2010 for 2011 gasoline vehicles. API CJ-4 was added in 2010 to meet four-stroke diesel engine requirements. New CK-4 (backward compatible) and FA-4 (not backward compatible) ratings came into effect in Dec 2016.

​The API symbol is the donut symbol located on the back of the oil bottle. In the top half of the symbol is the service class—S or C—and the service standard that the oil meets. The center part carries the SAE viscosity rating for the oil. The API symbol may also carry a “Resource Conserving” or “Energy Conserving” designation if it is a fuel-saving oil. Be sure to use oil that has a correct API rating and also an energy-conserving designation in all North American vehicles.

​The API also created a “starburst” symbol that can be placed on oil containers that meet the current engine protection standard and fuel economy requirements of the ILSAC, which is a joint effort of U.S. and Japanese automobile manufacturers.

​ Group 1 oils are produced by simple distillation of crude oil, which separates the components of the oil by their boiling point and by the use of solvents to extract sulfur, nitrogen, and oxygen compounds. This method was the only commercial refinement process until the early 1970s, and the bulk of commercial oil products on the market are still produced by this process, such as conventional engine oils.

​The API classifies oils into five groups:

​Group 2 and Group 3 oils are refined with hydrogen at much higher temperatures and pressures, in a process known as hydrocracking. This process results in a base mineral oil with many of the higher performance characteristics of synthetic oils.
The more heavily hydrocracked group 3 oils have a very high viscosity index (above 120) and many, but not all, of the higher performance characteristics of a full polyalphaolefin (PAO) synthetic oil. Although not fully synthetic, these oils can be sold as synthetic oil in North America. And because of their lower cost, many of the oils billed as “synthetic” are of group 3 base stock.

​Group 4 oils are all of the full synthetic PAO group (most common true synthetic). This synthetic oil has more robust qualities and benefits over group 3 oils.
Group 5 includes all other types of synthetic oil. Typically, group 5 oils are more expensive than group 4 oils, and although they are very thermally stable, they are more commonly used in aviation and industrial applications.

​International Lubricant Standardization and Approval Committee (ILSAC)

​ILSAC works in conjunction with the API in creating new specifications for gasoline engine oil. However, ILSAC requires that the oil provide increased fuel economy over a base lubricant. These oils should reduce vehicle owners’ fuel costs a small amount compared to an oil that does not meet the ILSAC standard. Like the API standard, ILSAC issues sequentially higher rating levels each time the standards are changed. ILSAC GF-5 replaced GF-4 and became the standard in October 2010. Engine oils that meet the highest ILSAC standard (currently GF-5) can display the API starburst symbol, which the API created to verify that the oil meets the highest ILSAC standard. The next ILSAC standard is scheduled to be called GF-6, and oils meeting the standard will be released by April 2018. This higher standard will allow engine manufacturers to keep enhancing their engines, with the goal of meeting the 2025 fuel economy standard of 54.4 mpg.

​Association des Constructeurs Européens d’Automobiles (ACEA)

​The ACEA classifications formulated for engine oils used in European vehicles are much more stringent than the API and ILSAC standards. Some of the characteristics the ACEA-rated oil must score high on are soot thickening, water, sludge, piston deposits, oxidative thickening, fuel economy, and aftertreatment compatibility. Although some of these may be tested by the API and ILSAC, the standards are set high to achieve ACEA certification ratings. This means that the engine oil provides additional protection or characteristics that API- or ILSAC-rated oils may not match. If you are servicing a European vehicle, it is advised that you do not go by any API recommendations; instead, make sure the oil meets the recommended ACEA rating specified by the manufacturer or the manufacturer’s own specification rating .

​Japanese Automotive Standards Organization (JASO)

​The JASO standards set the classification for motorcycle engines, both two stroke and four-stroke, as well as Japanese automotive diesel engines. For four cycle motorcycle engines, the JASO T 903:2011 came into effect in October 2011 and designates different ratings for wet clutch (MA) and dry clutch (MB). For two-stroke motorcycles, JASO M 35:2003 came into effect in October 2003. And for automotive diesel engines, JASO M355:2015 came into effect in October 2015.

​OEM-Specific Standards

​As engine manufacturers continued to design new features or longer drain intervals into their engines, faster than some of the oil rating organizations could (or would) change their standards, engine manufacturers came up with their own standards. These standards are specific to individual manufacturers or even individual engines of a particular manufacturer. A few examples follow: Oil meeting Volkswagen’s VW 506.00 standard is suitable for use on diesel engines (not with single injector pump), with an extended service interval of up to 31,000 miles or two years. Oil meeting General Motor’s dexos1™ was specified for use starting with all 2011 GM gasoline-powered vehicles and was backward compatible in all older GM vehicles.

​General Motor’s dexos2™ is specified for all GM vehicles equipped with Duramax diesel engines. Its viscosity is SAE 5W30 and meets the ACEA A3/B3 standard. It has a service interval of up to 18,600 miles. Oil meeting BMW’s Longlife-04 standard is approved for fully synthetic long-life oil and is usually required for BMWs equipped with a diesel particulate filter. As you can see, it is important to understand the oil requirements for the vehicle you are working on and only use the specified oil. Using the wrong oil can result in severe damage to the engine. Furthermore, using the wrong oil can void the customer’s warranty, leaving the customer, or your shop, responsible for repairs. Long gone are the days of grabbing five bottles of any 10W-30 oil off the shelf and putting it into any car that rolls through the door. So always research the specified oil requirements for the vehicle you are servicing before selecting an oil to use.