Engine Oil Viscocity
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Engine Oil Viscocity
Sticky please...
It took me so long to understand the Engine oil grading system since day 1 i join the member and got my car. This article was emailed to me by a friend.
so here is some understanding of how the engine oil is been graded for new members:
Here it Goes...
Most people are familiar with oil's Viscosity Rating—10W40, for example. However, very few know that the "W" refers to "winter," not "weight." And most of us have no idea what the weight-rating numbers mean other than that the vehicle's manufacturer specifies a particular viscosity. This story deals strictly with viscosity; we're saving the petroleum vs. synthetic debate for later.
Oil Duties
Inside an engine, oil is in a Catch-22 scenario: It has to seal rings and valves, but it also must reduce friction. In simple terms, oil has to accomplish two functions that have directly opposite requirements.
The viscosity of any oil changes with temperature. The higher the temperature, the lower the viscosity—the oil thins out. On the flipside, the lower the temperature the higher the viscosity. Because of this, the Society of Automotive Engineers (SAE) has established a series of viscosity classifications that establish oil performance at 100 and 0 degrees Celsius (212 and 32 degrees Fahrenheit, respectively).
Highs and Lows
Low-viscosity oils flow better than high-viscosity ones—the lighter-weight fluid is easier to pump and therefore circulates faster through the engine's various galleries. Low-viscosity oils also maintain a lower oil pressure, but the oil pump delivers a greater volume through the galleries than it would with thicker (higher-viscosity) oils. Heavier oils also tend to operate at higher temperatures because the oil pump has to work harder to force the lubricant through the system. Oil does not compress readily, so the added pressure increases the temperature. In the end, high-viscosity oils maintain a higher oil pressure, but the pump delivers a smaller volume of oil.
Multigrades
Multigrade oils typically begin as base oils, such as 10W. Then viscosity-index modifiers (polymers) are added in an effort to stabilize the viscosity. This allows a 10W40 oil to flow like a 10W at cold temperatures and a 40W at higher temperatures.
The multigrade oils' viscosity modifiers are long-chain molecules that lessen the change of viscosity with temperature variance. In the past, the polymer additives (used to thicken the oil) were sometimes susceptible to viscosity loss. Permanent viscosity loss occurred when high shear forces (such as the relationship between the main bearings and the crankshaft) actually break the polymer molecules into less-effective smaller pieces. On a similar note, temporary viscosity loss also occurred when the polymer molecules aligned themselves in order to create a path of least resistance.
Fortunately, today's additive packages have improved oil's shear-resistance. However, oils with the same rating from different manufacturers can exhibit different viscosity ratings in an operating engine, depending on the shear stability of their viscosity-modifying additives.
For technoids, weights are defined thusly (stokes and centistrokes are measurements of viscosity):
"SAE 30 is SAE 30 no matter what the "W" prefix number is: 0W, 5W or 10W. This viscosity in centistokes (cSt) @ 100 degrees C is with the minimum of 9.3 cSt and a maximum of 12.5 cSt.
"SAE 40 is SAE 40 no matter what the "W" prefix number is: 5W, 10W, 15W or 20W. The viscosity @ 100 degrees C is within the minim of 12.5 cSt and a maximum of 16.3 cSt.
"SAE 50 is SAE 50 no matter what the "W" prefix number is: 5W, 10W, 15W or 25W. The viscosity @ 100 degrees C is within the minimum of 16.3 cSt and a maximum of 21.9 cSt.
"SAE 60 is SAE 60 no matter what the "W" prefix number is: 10W, 15W or 25W. The viscosity @ 100 degrees C is within the minimum of 21.9 cSt and a maximum of 26.1 cSt.
"There is no SAE 70 and no one is likely to make one with a "W" prefix number although it is possible using a synthetic base oil. This viscosity is identified as Grade 70. The viscosity @ 100 degrees C has a minimum of 26.1 cSt and no maximum."
The difference between a multigrade and a singlegrade oil: The singlegrade can't pass the low temperature viscosity test. If it did meet one of the following "W" viscosities, it would be a multigrade.
Singlegrade oils will become obsolete for performance engines in the future. We dropped SAE 30 and SAE 40 because SAE 10W40 does everything 30 or 40 can do—and some things the straight grades can't do—like increasing horsepower. If an off-roader doesn't like 10W40, then use 20W50. It can do everything a 10W40 can do except pass the sub-zero viscosity test at -20 degrees C.
Multigrade viscosities are run at six different sub-zero temperatures. When a racing-oil designer puts a formula together, he has to know the viscosity at 100 degrees C of every component in the additive composition. He has to have a target viscosity objective for the finished oil in each SAE grade. Once a formula is established, the technician who supervises the blending has to duplicate this formula in the correct proportions every time the product is blended. The viscosity at 100 degrees C has a plus or minus written into the oil's quality-control specification.
Multigrade or Multi-Vis?
One oil manufacturer claims that "some people in the industry use multi-viscosity as if it means the same thing as multigrade. An oil cannot be multi-viscosity, but it can be multigrade by meeting the viscosity requirements for SAE 30, 40, 50 or 60 and one of the sub-zero "W" viscosity requirements. At one time, some oil companies labeled oils SAE 10W, 20W30—as if the oil could be 10W and 20W at the same time. This is impossible because 10W is measured at -20 degrees C and 20W is measured at -10 degrees C, which eliminates the multi-viscosity theory."
API Numbers
Shortly after WWII, the American Petroleum Institute (API) developed a system that established three basic types of engine oils: regular, premium and heavy-duty. Naturally, three oil classifications could never hope to cover all of the different applications ranging from conventional passenger cars to heavy-duty trucks. The API eventually realized that other variables had to be considered, such as the type of engine and its usage. In 1952, the API launched the service classifications system.
The API system revolves around two general classification: S for Service (typical passenger cars and light trucks) and C for commercial applications (typical diesel equipment). The breakdown of "S" varieties is as follows:
SA: This is a plain mineral oil that doesn't contain additives common in today's high-tech lubricants. This oil was primarily used in the 1920s and is obsolete today.
SB: Lubes that contain anti-wear and oxidation inhibitors as well as corrosion inhibitors. This oil was primarily in use prior to 1964 and was created for vehicles that saw moderate conditions.
SC: This classification was originally recommended for use in 1964-67 vehicles. It contains additives that control rust, wear, corrosion and engine deposits. It too is now obsolete.
SD: SD lubes were recommended for use in 1968-70 vehicles as well as certain post-1970 passenger cars. This oil contains the same additive packages as the SC class and can be used in place of it.
SE: This category was recommended for certain 1971 vehicles as well as most 1972 vehicles. This classification offers more protection than the SD group of lubricants and is suitable for severe-duty applications. This classification can be used in place of SD oils.
SF: Recommended with 1980 and newer passenger vehicles. This oil has superior anti-wear properties and enhanced oxidation stability over SE lubricants.
SG: The SG rating was introduced in 1989 and combined the performance properties of the commercial rating CC (lubricants designed for use in supercharged/turbocharged diesel applications in moderate to severe service).
SH: Now obsolete, SH was designed for 1996 and older engines.
SJ: Introduced in 1996, this rating is for all automotive engines presently in use.
Generally speaking, think of the API system as a blueprint for oil. In order to gain an API classification, oil manufacturers have to follow a set of limitations. This creates a few problems for oil companies, especially those who produce racing oils. Race oil must conform to viscosity-grade standards but not to those for chemical-additive composition and base-oil composition. That's why you'll find several brands of race oil without API classifications.
Race Oil
In the old days, high-performance "racing" oils were generally sold in a straight 50 grade. Today, you have much more choice. There are dozens upon dozens of oils to choose from (even from one manufacturer or "packager"). According to Torco, five questions should influence your selection of oil viscosity:
(1) Does the engine operate on racing gasoline, alcohol or nitromethane? (2) Is the powerplant normally aspirated, turbocharged or supercharged? (3) Is there an oxidizer such as nitrous oxide or propylene oxide present? (4) How long will the engine be running and if racing, what is the duration of the race? (5) How often is the oil changed?
The following are suggestions for viscosity based upon the format of racing. In these maximum-horsepower applications, the suggestions are based upon the assumption that synthetic oils are used.
Resources
Torco International, (800) 649 5722, www.torcoracingoils.com
Amsoil, www.amsoil.com
Castrol, www.castrol.com
Chevron, www.chevron.com
Citgo, www.citgo.com
Coastal Unilube, www.coastalunilube.com
ExxonMobil, www.exxon.com
Kendall/Sunoco, www.kendallmotoroil.com
Neo, www.neosyntheticoil.com
Pennzoil/Quaker State, www.pennzoilquakerstate.com
Phillips 66, www.tropartic.com
Red Line, www.redlineoil.com
Royal Purple, www.synerlec.com
Texaco/Shell, www.texaco.com
Torco, www.torcoracingoils.com
Valvoline, www.valvoline.com
It took me so long to understand the Engine oil grading system since day 1 i join the member and got my car. This article was emailed to me by a friend.
so here is some understanding of how the engine oil is been graded for new members:
Here it Goes...
Most people are familiar with oil's Viscosity Rating—10W40, for example. However, very few know that the "W" refers to "winter," not "weight." And most of us have no idea what the weight-rating numbers mean other than that the vehicle's manufacturer specifies a particular viscosity. This story deals strictly with viscosity; we're saving the petroleum vs. synthetic debate for later.
Oil Duties
Inside an engine, oil is in a Catch-22 scenario: It has to seal rings and valves, but it also must reduce friction. In simple terms, oil has to accomplish two functions that have directly opposite requirements.
The viscosity of any oil changes with temperature. The higher the temperature, the lower the viscosity—the oil thins out. On the flipside, the lower the temperature the higher the viscosity. Because of this, the Society of Automotive Engineers (SAE) has established a series of viscosity classifications that establish oil performance at 100 and 0 degrees Celsius (212 and 32 degrees Fahrenheit, respectively).
Highs and Lows
Low-viscosity oils flow better than high-viscosity ones—the lighter-weight fluid is easier to pump and therefore circulates faster through the engine's various galleries. Low-viscosity oils also maintain a lower oil pressure, but the oil pump delivers a greater volume through the galleries than it would with thicker (higher-viscosity) oils. Heavier oils also tend to operate at higher temperatures because the oil pump has to work harder to force the lubricant through the system. Oil does not compress readily, so the added pressure increases the temperature. In the end, high-viscosity oils maintain a higher oil pressure, but the pump delivers a smaller volume of oil.
Multigrades
Multigrade oils typically begin as base oils, such as 10W. Then viscosity-index modifiers (polymers) are added in an effort to stabilize the viscosity. This allows a 10W40 oil to flow like a 10W at cold temperatures and a 40W at higher temperatures.
The multigrade oils' viscosity modifiers are long-chain molecules that lessen the change of viscosity with temperature variance. In the past, the polymer additives (used to thicken the oil) were sometimes susceptible to viscosity loss. Permanent viscosity loss occurred when high shear forces (such as the relationship between the main bearings and the crankshaft) actually break the polymer molecules into less-effective smaller pieces. On a similar note, temporary viscosity loss also occurred when the polymer molecules aligned themselves in order to create a path of least resistance.
Fortunately, today's additive packages have improved oil's shear-resistance. However, oils with the same rating from different manufacturers can exhibit different viscosity ratings in an operating engine, depending on the shear stability of their viscosity-modifying additives.
For technoids, weights are defined thusly (stokes and centistrokes are measurements of viscosity):
"SAE 30 is SAE 30 no matter what the "W" prefix number is: 0W, 5W or 10W. This viscosity in centistokes (cSt) @ 100 degrees C is with the minimum of 9.3 cSt and a maximum of 12.5 cSt.
"SAE 40 is SAE 40 no matter what the "W" prefix number is: 5W, 10W, 15W or 20W. The viscosity @ 100 degrees C is within the minim of 12.5 cSt and a maximum of 16.3 cSt.
"SAE 50 is SAE 50 no matter what the "W" prefix number is: 5W, 10W, 15W or 25W. The viscosity @ 100 degrees C is within the minimum of 16.3 cSt and a maximum of 21.9 cSt.
"SAE 60 is SAE 60 no matter what the "W" prefix number is: 10W, 15W or 25W. The viscosity @ 100 degrees C is within the minimum of 21.9 cSt and a maximum of 26.1 cSt.
"There is no SAE 70 and no one is likely to make one with a "W" prefix number although it is possible using a synthetic base oil. This viscosity is identified as Grade 70. The viscosity @ 100 degrees C has a minimum of 26.1 cSt and no maximum."
The difference between a multigrade and a singlegrade oil: The singlegrade can't pass the low temperature viscosity test. If it did meet one of the following "W" viscosities, it would be a multigrade.
Singlegrade oils will become obsolete for performance engines in the future. We dropped SAE 30 and SAE 40 because SAE 10W40 does everything 30 or 40 can do—and some things the straight grades can't do—like increasing horsepower. If an off-roader doesn't like 10W40, then use 20W50. It can do everything a 10W40 can do except pass the sub-zero viscosity test at -20 degrees C.
Multigrade viscosities are run at six different sub-zero temperatures. When a racing-oil designer puts a formula together, he has to know the viscosity at 100 degrees C of every component in the additive composition. He has to have a target viscosity objective for the finished oil in each SAE grade. Once a formula is established, the technician who supervises the blending has to duplicate this formula in the correct proportions every time the product is blended. The viscosity at 100 degrees C has a plus or minus written into the oil's quality-control specification.
Multigrade or Multi-Vis?
One oil manufacturer claims that "some people in the industry use multi-viscosity as if it means the same thing as multigrade. An oil cannot be multi-viscosity, but it can be multigrade by meeting the viscosity requirements for SAE 30, 40, 50 or 60 and one of the sub-zero "W" viscosity requirements. At one time, some oil companies labeled oils SAE 10W, 20W30—as if the oil could be 10W and 20W at the same time. This is impossible because 10W is measured at -20 degrees C and 20W is measured at -10 degrees C, which eliminates the multi-viscosity theory."
API Numbers
Shortly after WWII, the American Petroleum Institute (API) developed a system that established three basic types of engine oils: regular, premium and heavy-duty. Naturally, three oil classifications could never hope to cover all of the different applications ranging from conventional passenger cars to heavy-duty trucks. The API eventually realized that other variables had to be considered, such as the type of engine and its usage. In 1952, the API launched the service classifications system.
The API system revolves around two general classification: S for Service (typical passenger cars and light trucks) and C for commercial applications (typical diesel equipment). The breakdown of "S" varieties is as follows:
SA: This is a plain mineral oil that doesn't contain additives common in today's high-tech lubricants. This oil was primarily used in the 1920s and is obsolete today.
SB: Lubes that contain anti-wear and oxidation inhibitors as well as corrosion inhibitors. This oil was primarily in use prior to 1964 and was created for vehicles that saw moderate conditions.
SC: This classification was originally recommended for use in 1964-67 vehicles. It contains additives that control rust, wear, corrosion and engine deposits. It too is now obsolete.
SD: SD lubes were recommended for use in 1968-70 vehicles as well as certain post-1970 passenger cars. This oil contains the same additive packages as the SC class and can be used in place of it.
SE: This category was recommended for certain 1971 vehicles as well as most 1972 vehicles. This classification offers more protection than the SD group of lubricants and is suitable for severe-duty applications. This classification can be used in place of SD oils.
SF: Recommended with 1980 and newer passenger vehicles. This oil has superior anti-wear properties and enhanced oxidation stability over SE lubricants.
SG: The SG rating was introduced in 1989 and combined the performance properties of the commercial rating CC (lubricants designed for use in supercharged/turbocharged diesel applications in moderate to severe service).
SH: Now obsolete, SH was designed for 1996 and older engines.
SJ: Introduced in 1996, this rating is for all automotive engines presently in use.
Generally speaking, think of the API system as a blueprint for oil. In order to gain an API classification, oil manufacturers have to follow a set of limitations. This creates a few problems for oil companies, especially those who produce racing oils. Race oil must conform to viscosity-grade standards but not to those for chemical-additive composition and base-oil composition. That's why you'll find several brands of race oil without API classifications.
Race Oil
In the old days, high-performance "racing" oils were generally sold in a straight 50 grade. Today, you have much more choice. There are dozens upon dozens of oils to choose from (even from one manufacturer or "packager"). According to Torco, five questions should influence your selection of oil viscosity:
(1) Does the engine operate on racing gasoline, alcohol or nitromethane? (2) Is the powerplant normally aspirated, turbocharged or supercharged? (3) Is there an oxidizer such as nitrous oxide or propylene oxide present? (4) How long will the engine be running and if racing, what is the duration of the race? (5) How often is the oil changed?
The following are suggestions for viscosity based upon the format of racing. In these maximum-horsepower applications, the suggestions are based upon the assumption that synthetic oils are used.
Resources
Torco International, (800) 649 5722, www.torcoracingoils.com
Amsoil, www.amsoil.com
Castrol, www.castrol.com
Chevron, www.chevron.com
Citgo, www.citgo.com
Coastal Unilube, www.coastalunilube.com
ExxonMobil, www.exxon.com
Kendall/Sunoco, www.kendallmotoroil.com
Neo, www.neosyntheticoil.com
Pennzoil/Quaker State, www.pennzoilquakerstate.com
Phillips 66, www.tropartic.com
Red Line, www.redlineoil.com
Royal Purple, www.synerlec.com
Texaco/Shell, www.texaco.com
Torco, www.torcoracingoils.com
Valvoline, www.valvoline.com
Last edited by theboy; Apr 4, 2006 at 03:36 AM.
Dee Dee Velocity Red
Joined: Jan 2006
Posts: 63
Likes: 0
From: Brunei Darussalam
Originally Posted by theboy
Sticky please...
It took me so long to understand the Engine oil grading system since day 1 i join the member and got my car. This article was emailed to me by a friend.
so here is some understanding of how the engine oil is been graded for new members:
Here it Goes...
Most people are familiar with oil's Viscosity Rating—10W40, for example. However, very few know that the "W" refers to "winter," not "weight." And most of us have no idea what the weight-rating numbers mean other than that the vehicle's manufacturer specifies a particular viscosity. This story deals strictly with viscosity; we're saving the petroleum vs. synthetic debate for later.
Oil Duties
Inside an engine, oil is in a Catch-22 scenario: It has to seal rings and valves, but it also must reduce friction. In simple terms, oil has to accomplish two functions that have directly opposite requirements.
The viscosity of any oil changes with temperature. The higher the temperature, the lower the viscosity—the oil thins out. On the flipside, the lower the temperature the higher the viscosity. Because of this, the Society of Automotive Engineers (SAE) has established a series of viscosity classifications that establish oil performance at 100 and 0 degrees Celsius (212 and 32 degrees Fahrenheit, respectively).
Highs and Lows
Low-viscosity oils flow better than high-viscosity ones—the lighter-weight fluid is easier to pump and therefore circulates faster through the engine's various galleries. Low-viscosity oils also maintain a lower oil pressure, but the oil pump delivers a greater volume through the galleries than it would with thicker (higher-viscosity) oils. Heavier oils also tend to operate at higher temperatures because the oil pump has to work harder to force the lubricant through the system. Oil does not compress readily, so the added pressure increases the temperature. In the end, high-viscosity oils maintain a higher oil pressure, but the pump delivers a smaller volume of oil.
Multigrades
Multigrade oils typically begin as base oils, such as 10W. Then viscosity-index modifiers (polymers) are added in an effort to stabilize the viscosity. This allows a 10W40 oil to flow like a 10W at cold temperatures and a 40W at higher temperatures.
The multigrade oils' viscosity modifiers are long-chain molecules that lessen the change of viscosity with temperature variance. In the past, the polymer additives (used to thicken the oil) were sometimes susceptible to viscosity loss. Permanent viscosity loss occurred when high shear forces (such as the relationship between the main bearings and the crankshaft) actually break the polymer molecules into less-effective smaller pieces. On a similar note, temporary viscosity loss also occurred when the polymer molecules aligned themselves in order to create a path of least resistance.
Fortunately, today's additive packages have improved oil's shear-resistance. However, oils with the same rating from different manufacturers can exhibit different viscosity ratings in an operating engine, depending on the shear stability of their viscosity-modifying additives.
For technoids, weights are defined thusly (stokes and centistrokes are measurements of viscosity):
"SAE 30 is SAE 30 no matter what the "W" prefix number is: 0W, 5W or 10W. This viscosity in centistokes (cSt) @ 100 degrees C is with the minimum of 9.3 cSt and a maximum of 12.5 cSt.
"SAE 40 is SAE 40 no matter what the "W" prefix number is: 5W, 10W, 15W or 20W. The viscosity @ 100 degrees C is within the minim of 12.5 cSt and a maximum of 16.3 cSt.
"SAE 50 is SAE 50 no matter what the "W" prefix number is: 5W, 10W, 15W or 25W. The viscosity @ 100 degrees C is within the minimum of 16.3 cSt and a maximum of 21.9 cSt.
"SAE 60 is SAE 60 no matter what the "W" prefix number is: 10W, 15W or 25W. The viscosity @ 100 degrees C is within the minimum of 21.9 cSt and a maximum of 26.1 cSt.
"There is no SAE 70 and no one is likely to make one with a "W" prefix number although it is possible using a synthetic base oil. This viscosity is identified as Grade 70. The viscosity @ 100 degrees C has a minimum of 26.1 cSt and no maximum."
The difference between a multigrade and a singlegrade oil: The singlegrade can't pass the low temperature viscosity test. If it did meet one of the following "W" viscosities, it would be a multigrade.
Singlegrade oils will become obsolete for performance engines in the future. We dropped SAE 30 and SAE 40 because SAE 10W40 does everything 30 or 40 can do—and some things the straight grades can't do—like increasing horsepower. If an off-roader doesn't like 10W40, then use 20W50. It can do everything a 10W40 can do except pass the sub-zero viscosity test at -20 degrees C.
Multigrade viscosities are run at six different sub-zero temperatures. When a racing-oil designer puts a formula together, he has to know the viscosity at 100 degrees C of every component in the additive composition. He has to have a target viscosity objective for the finished oil in each SAE grade. Once a formula is established, the technician who supervises the blending has to duplicate this formula in the correct proportions every time the product is blended. The viscosity at 100 degrees C has a plus or minus written into the oil's quality-control specification.
Multigrade or Multi-Vis?
One oil manufacturer claims that "some people in the industry use multi-viscosity as if it means the same thing as multigrade. An oil cannot be multi-viscosity, but it can be multigrade by meeting the viscosity requirements for SAE 30, 40, 50 or 60 and one of the sub-zero "W" viscosity requirements. At one time, some oil companies labeled oils SAE 10W, 20W30—as if the oil could be 10W and 20W at the same time. This is impossible because 10W is measured at -20 degrees C and 20W is measured at -10 degrees C, which eliminates the multi-viscosity theory."
API Numbers
Shortly after WWII, the American Petroleum Institute (API) developed a system that established three basic types of engine oils: regular, premium and heavy-duty. Naturally, three oil classifications could never hope to cover all of the different applications ranging from conventional passenger cars to heavy-duty trucks. The API eventually realized that other variables had to be considered, such as the type of engine and its usage. In 1952, the API launched the service classifications system.
The API system revolves around two general classification: S for Service (typical passenger cars and light trucks) and C for commercial applications (typical diesel equipment). The breakdown of "S" varieties is as follows:
SA: This is a plain mineral oil that doesn't contain additives common in today's high-tech lubricants. This oil was primarily used in the 1920s and is obsolete today.
SB: Lubes that contain anti-wear and oxidation inhibitors as well as corrosion inhibitors. This oil was primarily in use prior to 1964 and was created for vehicles that saw moderate conditions.
SC: This classification was originally recommended for use in 1964-67 vehicles. It contains additives that control rust, wear, corrosion and engine deposits. It too is now obsolete.
SD: SD lubes were recommended for use in 1968-70 vehicles as well as certain post-1970 passenger cars. This oil contains the same additive packages as the SC class and can be used in place of it.
SE: This category was recommended for certain 1971 vehicles as well as most 1972 vehicles. This classification offers more protection than the SD group of lubricants and is suitable for severe-duty applications. This classification can be used in place of SD oils.
SF: Recommended with 1980 and newer passenger vehicles. This oil has superior anti-wear properties and enhanced oxidation stability over SE lubricants.
SG: The SG rating was introduced in 1989 and combined the performance properties of the commercial rating CC (lubricants designed for use in supercharged/turbocharged diesel applications in moderate to severe service).
SH: Now obsolete, SH was designed for 1996 and older engines.
SJ: Introduced in 1996, this rating is for all automotive engines presently in use.
Generally speaking, think of the API system as a blueprint for oil. In order to gain an API classification, oil manufacturers have to follow a set of limitations. This creates a few problems for oil companies, especially those who produce racing oils. Race oil must conform to viscosity-grade standards but not to those for chemical-additive composition and base-oil composition. That's why you'll find several brands of race oil without API classifications.
Race Oil
In the old days, high-performance "racing" oils were generally sold in a straight 50 grade. Today, you have much more choice. There are dozens upon dozens of oils to choose from (even from one manufacturer or "packager"). According to Torco, five questions should influence your selection of oil viscosity:
(1) Does the engine operate on racing gasoline, alcohol or nitromethane? (2) Is the powerplant normally aspirated, turbocharged or supercharged? (3) Is there an oxidizer such as nitrous oxide or propylene oxide present? (4) How long will the engine be running and if racing, what is the duration of the race? (5) How often is the oil changed?
The following are suggestions for viscosity based upon the format of racing. In these maximum-horsepower applications, the suggestions are based upon the assumption that synthetic oils are used.
Resources
Torco International, (800) 649 5722, www.torcoracingoils.com
Amsoil, www.amsoil.com
Castrol, www.castrol.com
Chevron, www.chevron.com
Citgo, www.citgo.com
Coastal Unilube, www.coastalunilube.com
ExxonMobil, www.exxon.com
Kendall/Sunoco, www.kendallmotoroil.com
Neo, www.neosyntheticoil.com
Pennzoil/Quaker State, www.pennzoilquakerstate.com
Phillips 66, www.tropartic.com
Red Line, www.redlineoil.com
Royal Purple, www.synerlec.com
Texaco/Shell, www.texaco.com
Torco, www.torcoracingoils.com
Valvoline, www.valvoline.com
It took me so long to understand the Engine oil grading system since day 1 i join the member and got my car. This article was emailed to me by a friend.
so here is some understanding of how the engine oil is been graded for new members:
Here it Goes...
Most people are familiar with oil's Viscosity Rating—10W40, for example. However, very few know that the "W" refers to "winter," not "weight." And most of us have no idea what the weight-rating numbers mean other than that the vehicle's manufacturer specifies a particular viscosity. This story deals strictly with viscosity; we're saving the petroleum vs. synthetic debate for later.
Oil Duties
Inside an engine, oil is in a Catch-22 scenario: It has to seal rings and valves, but it also must reduce friction. In simple terms, oil has to accomplish two functions that have directly opposite requirements.
The viscosity of any oil changes with temperature. The higher the temperature, the lower the viscosity—the oil thins out. On the flipside, the lower the temperature the higher the viscosity. Because of this, the Society of Automotive Engineers (SAE) has established a series of viscosity classifications that establish oil performance at 100 and 0 degrees Celsius (212 and 32 degrees Fahrenheit, respectively).
Highs and Lows
Low-viscosity oils flow better than high-viscosity ones—the lighter-weight fluid is easier to pump and therefore circulates faster through the engine's various galleries. Low-viscosity oils also maintain a lower oil pressure, but the oil pump delivers a greater volume through the galleries than it would with thicker (higher-viscosity) oils. Heavier oils also tend to operate at higher temperatures because the oil pump has to work harder to force the lubricant through the system. Oil does not compress readily, so the added pressure increases the temperature. In the end, high-viscosity oils maintain a higher oil pressure, but the pump delivers a smaller volume of oil.
Multigrades
Multigrade oils typically begin as base oils, such as 10W. Then viscosity-index modifiers (polymers) are added in an effort to stabilize the viscosity. This allows a 10W40 oil to flow like a 10W at cold temperatures and a 40W at higher temperatures.
The multigrade oils' viscosity modifiers are long-chain molecules that lessen the change of viscosity with temperature variance. In the past, the polymer additives (used to thicken the oil) were sometimes susceptible to viscosity loss. Permanent viscosity loss occurred when high shear forces (such as the relationship between the main bearings and the crankshaft) actually break the polymer molecules into less-effective smaller pieces. On a similar note, temporary viscosity loss also occurred when the polymer molecules aligned themselves in order to create a path of least resistance.
Fortunately, today's additive packages have improved oil's shear-resistance. However, oils with the same rating from different manufacturers can exhibit different viscosity ratings in an operating engine, depending on the shear stability of their viscosity-modifying additives.
For technoids, weights are defined thusly (stokes and centistrokes are measurements of viscosity):
"SAE 30 is SAE 30 no matter what the "W" prefix number is: 0W, 5W or 10W. This viscosity in centistokes (cSt) @ 100 degrees C is with the minimum of 9.3 cSt and a maximum of 12.5 cSt.
"SAE 40 is SAE 40 no matter what the "W" prefix number is: 5W, 10W, 15W or 20W. The viscosity @ 100 degrees C is within the minim of 12.5 cSt and a maximum of 16.3 cSt.
"SAE 50 is SAE 50 no matter what the "W" prefix number is: 5W, 10W, 15W or 25W. The viscosity @ 100 degrees C is within the minimum of 16.3 cSt and a maximum of 21.9 cSt.
"SAE 60 is SAE 60 no matter what the "W" prefix number is: 10W, 15W or 25W. The viscosity @ 100 degrees C is within the minimum of 21.9 cSt and a maximum of 26.1 cSt.
"There is no SAE 70 and no one is likely to make one with a "W" prefix number although it is possible using a synthetic base oil. This viscosity is identified as Grade 70. The viscosity @ 100 degrees C has a minimum of 26.1 cSt and no maximum."
The difference between a multigrade and a singlegrade oil: The singlegrade can't pass the low temperature viscosity test. If it did meet one of the following "W" viscosities, it would be a multigrade.
Singlegrade oils will become obsolete for performance engines in the future. We dropped SAE 30 and SAE 40 because SAE 10W40 does everything 30 or 40 can do—and some things the straight grades can't do—like increasing horsepower. If an off-roader doesn't like 10W40, then use 20W50. It can do everything a 10W40 can do except pass the sub-zero viscosity test at -20 degrees C.
Multigrade viscosities are run at six different sub-zero temperatures. When a racing-oil designer puts a formula together, he has to know the viscosity at 100 degrees C of every component in the additive composition. He has to have a target viscosity objective for the finished oil in each SAE grade. Once a formula is established, the technician who supervises the blending has to duplicate this formula in the correct proportions every time the product is blended. The viscosity at 100 degrees C has a plus or minus written into the oil's quality-control specification.
Multigrade or Multi-Vis?
One oil manufacturer claims that "some people in the industry use multi-viscosity as if it means the same thing as multigrade. An oil cannot be multi-viscosity, but it can be multigrade by meeting the viscosity requirements for SAE 30, 40, 50 or 60 and one of the sub-zero "W" viscosity requirements. At one time, some oil companies labeled oils SAE 10W, 20W30—as if the oil could be 10W and 20W at the same time. This is impossible because 10W is measured at -20 degrees C and 20W is measured at -10 degrees C, which eliminates the multi-viscosity theory."
API Numbers
Shortly after WWII, the American Petroleum Institute (API) developed a system that established three basic types of engine oils: regular, premium and heavy-duty. Naturally, three oil classifications could never hope to cover all of the different applications ranging from conventional passenger cars to heavy-duty trucks. The API eventually realized that other variables had to be considered, such as the type of engine and its usage. In 1952, the API launched the service classifications system.
The API system revolves around two general classification: S for Service (typical passenger cars and light trucks) and C for commercial applications (typical diesel equipment). The breakdown of "S" varieties is as follows:
SA: This is a plain mineral oil that doesn't contain additives common in today's high-tech lubricants. This oil was primarily used in the 1920s and is obsolete today.
SB: Lubes that contain anti-wear and oxidation inhibitors as well as corrosion inhibitors. This oil was primarily in use prior to 1964 and was created for vehicles that saw moderate conditions.
SC: This classification was originally recommended for use in 1964-67 vehicles. It contains additives that control rust, wear, corrosion and engine deposits. It too is now obsolete.
SD: SD lubes were recommended for use in 1968-70 vehicles as well as certain post-1970 passenger cars. This oil contains the same additive packages as the SC class and can be used in place of it.
SE: This category was recommended for certain 1971 vehicles as well as most 1972 vehicles. This classification offers more protection than the SD group of lubricants and is suitable for severe-duty applications. This classification can be used in place of SD oils.
SF: Recommended with 1980 and newer passenger vehicles. This oil has superior anti-wear properties and enhanced oxidation stability over SE lubricants.
SG: The SG rating was introduced in 1989 and combined the performance properties of the commercial rating CC (lubricants designed for use in supercharged/turbocharged diesel applications in moderate to severe service).
SH: Now obsolete, SH was designed for 1996 and older engines.
SJ: Introduced in 1996, this rating is for all automotive engines presently in use.
Generally speaking, think of the API system as a blueprint for oil. In order to gain an API classification, oil manufacturers have to follow a set of limitations. This creates a few problems for oil companies, especially those who produce racing oils. Race oil must conform to viscosity-grade standards but not to those for chemical-additive composition and base-oil composition. That's why you'll find several brands of race oil without API classifications.
Race Oil
In the old days, high-performance "racing" oils were generally sold in a straight 50 grade. Today, you have much more choice. There are dozens upon dozens of oils to choose from (even from one manufacturer or "packager"). According to Torco, five questions should influence your selection of oil viscosity:
(1) Does the engine operate on racing gasoline, alcohol or nitromethane? (2) Is the powerplant normally aspirated, turbocharged or supercharged? (3) Is there an oxidizer such as nitrous oxide or propylene oxide present? (4) How long will the engine be running and if racing, what is the duration of the race? (5) How often is the oil changed?
The following are suggestions for viscosity based upon the format of racing. In these maximum-horsepower applications, the suggestions are based upon the assumption that synthetic oils are used.
Resources
Torco International, (800) 649 5722, www.torcoracingoils.com
Amsoil, www.amsoil.com
Castrol, www.castrol.com
Chevron, www.chevron.com
Citgo, www.citgo.com
Coastal Unilube, www.coastalunilube.com
ExxonMobil, www.exxon.com
Kendall/Sunoco, www.kendallmotoroil.com
Neo, www.neosyntheticoil.com
Pennzoil/Quaker State, www.pennzoilquakerstate.com
Phillips 66, www.tropartic.com
Red Line, www.redlineoil.com
Royal Purple, www.synerlec.com
Texaco/Shell, www.texaco.com
Torco, www.torcoracingoils.com
Valvoline, www.valvoline.com
Thread Starter
RX8 newbie!
Joined: Jan 2006
Posts: 2,362
Likes: 0
Originally Posted by ddrx8
Halo tauke, saw your car pic and your forum regarding oil, good one lo. Jus wondering hav u driven your rx to Brunei? Heard you buy yours in Brunei, is that right?
Lubricious
Joined: Oct 2003
Posts: 3,425
Likes: 4
From: SF Bay Area, California
Originally Posted by theboy
Nubo i don't get what u mean? can u explain briefly? what is API and SL
Anyway,
Look at the original post section titled "API Numbers". The service classifications listed in the post, run through SJ.
However, service classification SL superseded SJ a few years ago. Look in your owners' guide for the oil requirement. Oil containers will list the service classification that they meet. Don't use one with a lower classification than what is called for in the manual.
My point is that the post is a copy of old information. The statement:
SJ: Introduced in 1996, this rating is for all automotive engines presently in use.
Last edited by Nubo; Apr 5, 2006 at 02:07 PM.
Thread Starter
RX8 newbie!
Joined: Jan 2006
Posts: 2,362
Likes: 0
Like i stated earlier, i got this from a friend. it doesn't matter its up to date or not. its still have a great value for new member like me. it really give understanding to viscosity grading and function of engine oil for our 8.
p/s: i cannot find the "API Number" thread u talking about. it might be years old. and some people like me with PI car doesn't have car manual. and its doesn't even match our country's climate. ^.^
p/s: i cannot find the "API Number" thread u talking about. it might be years old. and some people like me with PI car doesn't have car manual. and its doesn't even match our country's climate. ^.^
Lubricious
Joined: Oct 2003
Posts: 3,425
Likes: 4
From: SF Bay Area, California
Originally Posted by theboy
p/s: i cannot find the "API Number" thread u talking about.
Anyway, I didn't mean to give you a hard time. I don't know how this became an argument. I can't think of any way to make my point any clearer so I'll stop.
Peace
Thread Starter
RX8 newbie!
Joined: Jan 2006
Posts: 2,362
Likes: 0
Originally Posted by Nubo
Does the image below ring a bell...?
Anyway, I didn't mean to give you a hard time. I don't know how this became an argument. I can't think of any way to make my point any clearer so I'll stop.
Peace
Anyway, I didn't mean to give you a hard time. I don't know how this became an argument. I can't think of any way to make my point any clearer so I'll stop.
Peace
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