Chongo
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All about oil page 1 of 5
All About Oil
Why do we need oil?
We put oil in our engines to serve several purposes. First, obviously, oil acts as a lubricant. If your engine is operating correctly, there is almost no metal to metal contact - everything is riding on a thin film of oil. However, oil has several other important jobs to do. Oil circulates throughout your engine, and cools parts that cannot get near a water jacket. For example, it's becoming common in sport bikes to spray oil on the underside of the piston to cool it. There are no water jackets at all in your transmission. Motorcycle transmissions are oil cooled. Your piston rings do not do a perfect job of sealing. Some combustion by products will slip past the rings into the engine. This can be little particles of carbon. Remember, diamond is carbon that was combined under heat and pressure. These little carbon particles can be quite damaging to your engine. Another job of your oil is to hold these particles in suspension until the oil filter can grab them. Also, if your gasoline has sulpher in it (it does), this sulpher can react with water and oxygen to make sulpheric acid. This is some stuff that is seriously bad for your engine. Your oil has special ingredients in it called buffers to neutralize the sulpheric acid. Finally, your engine can get internal build ups of tars, waxes, and other gunk. Your oil has solvents to try to dissolve this stuff and get and keep your engine clean.
Where Oil Comes From
Most of the bio-mass on earth is single cell plants and microscopic critters in the ocean. When these die, they sink to the bottom. Often they fall into a deep crevasse or trench, where they may become covered up by an underwater landslide. After a couple hundred million years of high pressure and no air, the critters get squished into oil. So, oil isn't really "dead dinosaurs," but Sinclair Oil stations just wouldn't be the same with a picture of algie on their sign. Today we like to find this stuff, pump it to the surface, and burn it.
The oil we pump to the surface is a mixture of gasoline, kerosene, light weight lubricating oil, motor oil, gear oil, tars, paraffins, waxes, asphalt, sand, dirt, organic stuff (called aromatics) and the occasional dead cockroach. We call this stuff crude oil, for reasons that I think are now self-explanitory. The oil companies have the singularly smelly job of separating the crude oil into its component parts. A hundred years ago we would just heat the stuff up in a complicated still, and catch stuff that boiled off at different temperatures. Fifty years ago we started processing the crude oil with clay and solvents to do a more precise job. Today, we use very complicated systems where we heat the crude oil to precise temperatures, put it under high pressure, and bubble hydrogen and other stuff through it. The idea of all this is to try to get pure chemicals out of this stuff that we just found laying around in the desert.
Most motor oil has a lot of different chemicals in it with very different properties. The temperature at which the oil will start burning, called the flash point, is determined by the chemicals that burn at the lowest temperature. The higher the flash point, the more stable the oil is at high temperatures, and the less oil your engine will burn. The pour point is the temperature at which the oil stops flowing like a liquid. The lower this number is, the better protected your engine is when it's cold. The thickness of the oil, that is the resistance the oil offers to motion, is called the viscosity. The viscosity depends on all of the various chemicals in the oil and how they react to each other and to heat. Importantly, as the oil heats up, it thins out, that is the viscosity goes down. The better the oil is at retaining its viscosity at high temperatures, the higher the viscosity index. All of these properties depend on all the chemicals in the oil. If you could get only one precise kind of molecule out of the raw oil, you could do a lot better than you can do with a mix.
Refining Oil
The oil product you buy starts as a base oil. The base oil makes up about 85% of the oil you buy. The base oil can be refined from crude oil, chemically (synthetically) manufactured, or a blended combination.
Base oils that are refined from crude oil are colorless and pretty much odorless and are sold to the public as mineral oil. The curde oil is a combination of a lot of different chemicals, ranging from light gasolive types of fuels to waxes and tars. When you heat the crude oil, the gasolene and diesel oil boil off pretty early. Unfortunately, the mineral oil, paraffin, wax and tar molecules are all hooked up with each other, and it's not so easy to seperate them from each other. There are currently 5 classes of base oil, called Group I, II, III, IV, and V. Group I oil is refined the old-fashioned way using clay and solvents, and is used in about 2/3 of the oil sold in America today. Group I oils contain a fair amount of pariffin and wax. These molecules cause several problems in an engine: they sometimes fall out of solution, leading to buildups in your engine that must be cleaned out somehow. Also, as these molecules get hot they thin out quite a bit, much more than mineral oil, so they make the oil's high temperature performance rather poor.
In 1990, Chevron developed a new method of refining base oils called Hydrocracking, where you process the raw oil at high temperatures and pressures with hydrogen. In Hydrocracking, many of the pariffin and wax molecules are broken up into mineral oil molecules, which increases the performance of the base oil dramatically. Base oils made with this method are called Group II, and are significantly more pure and have higher performance than Group I base oils. Chevron Delo 400, Mobil Delvac 1300, and Shell Rotella are made from pure Group II oils. Motor oils made with hydrocracked base oils leave far fewer wax and tar deposits in your engine, and have much better high temperature performance than group I oils.
Since 1990, Chevron's process has been improved. By increasing the severity of the hydrocracking process, raising the temperature and pressure to break up more and more of the unwanted wax and pariffin molecules, the viscosity index (VI) can be improved further. The VI tells us how much the oil thins out as it gets hot. Oils with higher VIs maintain their viscosity better at high temperatures. If the VI is 90 to 100, we call it Group II; if it's refined to a VI of 110 to 115 we call it Group IIa. In the late '90s, an even more involved process was invented yielding base oils with VIs over 120. These base oils are called Group III or "unconventional base oils." The higher the VI, the fewer additives are necessary to achieve the required viscosity. For example fewer additives are needed to turn a Group III base oil into 10w-40 than are required for Group II base oils.
These Group III oils have properties approaching synthetics, so long as the temperature is above about 40°. Group III based oils are often claimed to not perform as well as synthetics in a couple ways: their low temperature performance is not nearly as good, it is sometimes claimed on the basis of the "ball bearing test" that they offer lower impact resistance, and since their flash point is slightly lower it is claimed that they burn off more easily. However, most modern engines are water-cooler, so it's hard to see how the slightly better flash points of the synthetics ever come into play. I personally don't make a habit of dropping a handful of ball bearing into my oil pan, so I'm not completely clear on what the impact tests mean to me. The low temperature performance of the Group III oils can be improved enormously by blending in a relatively small amount of synthetic base stock.
In the late 1990s, Castrol started selling an oil made from Group III base oil and called it SynTec Full Synthetic. Mobil sued Castrol, asserting that this oil was not synthetic, but simply a highly refined petroleum oil, and therefore it was false advertising to call it synthetic. In 1999, Mobil lost their lawsuit. It was decided that the word "synthetic" was a marketing term and referred to properties, not to production methods or ingredients. Castrol continues to make SynTec out of Group III base oils, that is highly purified oil with most all of the cockroach bits removed.
Shortly after Mobil lost their lawsuit, most oil companies started reformulating their synthetic oils to use Group III base stocks instead of PAOs or diester stocks as their primary component. Most of the "synthetic oil" you can buy today is actually mostly made of this highly-distilled and purified dino-juice called Group III oil. Group III base oils cost about half as much as the synthetics. By using a blend of mostly Group III oils and a smaller amount of "true" synthetics, the oil companies can produce a product that has nearly the same properties as the "true" synthetics, and nearly the same cost as the Group III oil. In fact, Mobil-1 is now primarily made from Group III unconventional base oils, exactly the stuff Mobil was claiming was not really synthetic. The much more expensive traditional synthetics are now available in their pure forms only in more expensive and harder to obtain oils.
Synthetic Oils
Synthetic oils were originally designed for the purpose of having a very pure base oil with excellent properties. By starting from scratch and building up your oil molecules from little pieces, you can pretty much guarantee that every molecule in the oil is just like every other molecule, and therefore the properties are exactly what you designed in, not compromised by impurities from dead cockroach shells or whatever. Synthetics were thus originally a reaction to the relatively poor refining processes available from about 1930 to about 1990. The original synthetics were designed for the Army Air Force in WW II.
All About Oil
Why do we need oil?
We put oil in our engines to serve several purposes. First, obviously, oil acts as a lubricant. If your engine is operating correctly, there is almost no metal to metal contact - everything is riding on a thin film of oil. However, oil has several other important jobs to do. Oil circulates throughout your engine, and cools parts that cannot get near a water jacket. For example, it's becoming common in sport bikes to spray oil on the underside of the piston to cool it. There are no water jackets at all in your transmission. Motorcycle transmissions are oil cooled. Your piston rings do not do a perfect job of sealing. Some combustion by products will slip past the rings into the engine. This can be little particles of carbon. Remember, diamond is carbon that was combined under heat and pressure. These little carbon particles can be quite damaging to your engine. Another job of your oil is to hold these particles in suspension until the oil filter can grab them. Also, if your gasoline has sulpher in it (it does), this sulpher can react with water and oxygen to make sulpheric acid. This is some stuff that is seriously bad for your engine. Your oil has special ingredients in it called buffers to neutralize the sulpheric acid. Finally, your engine can get internal build ups of tars, waxes, and other gunk. Your oil has solvents to try to dissolve this stuff and get and keep your engine clean.
Where Oil Comes From
Most of the bio-mass on earth is single cell plants and microscopic critters in the ocean. When these die, they sink to the bottom. Often they fall into a deep crevasse or trench, where they may become covered up by an underwater landslide. After a couple hundred million years of high pressure and no air, the critters get squished into oil. So, oil isn't really "dead dinosaurs," but Sinclair Oil stations just wouldn't be the same with a picture of algie on their sign. Today we like to find this stuff, pump it to the surface, and burn it.
The oil we pump to the surface is a mixture of gasoline, kerosene, light weight lubricating oil, motor oil, gear oil, tars, paraffins, waxes, asphalt, sand, dirt, organic stuff (called aromatics) and the occasional dead cockroach. We call this stuff crude oil, for reasons that I think are now self-explanitory. The oil companies have the singularly smelly job of separating the crude oil into its component parts. A hundred years ago we would just heat the stuff up in a complicated still, and catch stuff that boiled off at different temperatures. Fifty years ago we started processing the crude oil with clay and solvents to do a more precise job. Today, we use very complicated systems where we heat the crude oil to precise temperatures, put it under high pressure, and bubble hydrogen and other stuff through it. The idea of all this is to try to get pure chemicals out of this stuff that we just found laying around in the desert.
Most motor oil has a lot of different chemicals in it with very different properties. The temperature at which the oil will start burning, called the flash point, is determined by the chemicals that burn at the lowest temperature. The higher the flash point, the more stable the oil is at high temperatures, and the less oil your engine will burn. The pour point is the temperature at which the oil stops flowing like a liquid. The lower this number is, the better protected your engine is when it's cold. The thickness of the oil, that is the resistance the oil offers to motion, is called the viscosity. The viscosity depends on all of the various chemicals in the oil and how they react to each other and to heat. Importantly, as the oil heats up, it thins out, that is the viscosity goes down. The better the oil is at retaining its viscosity at high temperatures, the higher the viscosity index. All of these properties depend on all the chemicals in the oil. If you could get only one precise kind of molecule out of the raw oil, you could do a lot better than you can do with a mix.
Refining Oil
The oil product you buy starts as a base oil. The base oil makes up about 85% of the oil you buy. The base oil can be refined from crude oil, chemically (synthetically) manufactured, or a blended combination.
Base oils that are refined from crude oil are colorless and pretty much odorless and are sold to the public as mineral oil. The curde oil is a combination of a lot of different chemicals, ranging from light gasolive types of fuels to waxes and tars. When you heat the crude oil, the gasolene and diesel oil boil off pretty early. Unfortunately, the mineral oil, paraffin, wax and tar molecules are all hooked up with each other, and it's not so easy to seperate them from each other. There are currently 5 classes of base oil, called Group I, II, III, IV, and V. Group I oil is refined the old-fashioned way using clay and solvents, and is used in about 2/3 of the oil sold in America today. Group I oils contain a fair amount of pariffin and wax. These molecules cause several problems in an engine: they sometimes fall out of solution, leading to buildups in your engine that must be cleaned out somehow. Also, as these molecules get hot they thin out quite a bit, much more than mineral oil, so they make the oil's high temperature performance rather poor.
In 1990, Chevron developed a new method of refining base oils called Hydrocracking, where you process the raw oil at high temperatures and pressures with hydrogen. In Hydrocracking, many of the pariffin and wax molecules are broken up into mineral oil molecules, which increases the performance of the base oil dramatically. Base oils made with this method are called Group II, and are significantly more pure and have higher performance than Group I base oils. Chevron Delo 400, Mobil Delvac 1300, and Shell Rotella are made from pure Group II oils. Motor oils made with hydrocracked base oils leave far fewer wax and tar deposits in your engine, and have much better high temperature performance than group I oils.
Since 1990, Chevron's process has been improved. By increasing the severity of the hydrocracking process, raising the temperature and pressure to break up more and more of the unwanted wax and pariffin molecules, the viscosity index (VI) can be improved further. The VI tells us how much the oil thins out as it gets hot. Oils with higher VIs maintain their viscosity better at high temperatures. If the VI is 90 to 100, we call it Group II; if it's refined to a VI of 110 to 115 we call it Group IIa. In the late '90s, an even more involved process was invented yielding base oils with VIs over 120. These base oils are called Group III or "unconventional base oils." The higher the VI, the fewer additives are necessary to achieve the required viscosity. For example fewer additives are needed to turn a Group III base oil into 10w-40 than are required for Group II base oils.
These Group III oils have properties approaching synthetics, so long as the temperature is above about 40°. Group III based oils are often claimed to not perform as well as synthetics in a couple ways: their low temperature performance is not nearly as good, it is sometimes claimed on the basis of the "ball bearing test" that they offer lower impact resistance, and since their flash point is slightly lower it is claimed that they burn off more easily. However, most modern engines are water-cooler, so it's hard to see how the slightly better flash points of the synthetics ever come into play. I personally don't make a habit of dropping a handful of ball bearing into my oil pan, so I'm not completely clear on what the impact tests mean to me. The low temperature performance of the Group III oils can be improved enormously by blending in a relatively small amount of synthetic base stock.
In the late 1990s, Castrol started selling an oil made from Group III base oil and called it SynTec Full Synthetic. Mobil sued Castrol, asserting that this oil was not synthetic, but simply a highly refined petroleum oil, and therefore it was false advertising to call it synthetic. In 1999, Mobil lost their lawsuit. It was decided that the word "synthetic" was a marketing term and referred to properties, not to production methods or ingredients. Castrol continues to make SynTec out of Group III base oils, that is highly purified oil with most all of the cockroach bits removed.
Shortly after Mobil lost their lawsuit, most oil companies started reformulating their synthetic oils to use Group III base stocks instead of PAOs or diester stocks as their primary component. Most of the "synthetic oil" you can buy today is actually mostly made of this highly-distilled and purified dino-juice called Group III oil. Group III base oils cost about half as much as the synthetics. By using a blend of mostly Group III oils and a smaller amount of "true" synthetics, the oil companies can produce a product that has nearly the same properties as the "true" synthetics, and nearly the same cost as the Group III oil. In fact, Mobil-1 is now primarily made from Group III unconventional base oils, exactly the stuff Mobil was claiming was not really synthetic. The much more expensive traditional synthetics are now available in their pure forms only in more expensive and harder to obtain oils.
Synthetic Oils
Synthetic oils were originally designed for the purpose of having a very pure base oil with excellent properties. By starting from scratch and building up your oil molecules from little pieces, you can pretty much guarantee that every molecule in the oil is just like every other molecule, and therefore the properties are exactly what you designed in, not compromised by impurities from dead cockroach shells or whatever. Synthetics were thus originally a reaction to the relatively poor refining processes available from about 1930 to about 1990. The original synthetics were designed for the Army Air Force in WW II.
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