What is CCS viscosity and what is it's relevance of determining cold weather oil performance in relation to Kinematic Viscosity and Pour Point.
Thanks.
Thanks.
Please explain CCS viscosity, ASTM D 5293
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I believe CCS viscosity refers to pumpability. Kinematic viscosity and pour point refer to the oil's ability to flow freely, which is different.
I can't remember where I heard it but the best illustration I've seen of the difference between pumpability and flow rate is Jello: when it's fully made, it won't flow, but you could suck it up through a straw (i.e. it is pumpable).
I can't remember where I heard it but the best illustration I've seen of the difference between pumpability and flow rate is Jello: when it's fully made, it won't flow, but you could suck it up through a straw (i.e. it is pumpable).
CCS is used because oil becomes relatively unpredictable under 0 degrees Celsius. With CCS, you can see how fast oil flows when cranked at a low temperature. Sometimes, oils with higher viscosity flow better at those low temperatures.
For example 0w40 vs. 5w20
For example 0w40 vs. 5w20
The jello example is a good one.
The viscosity of many liquids, oil included, vary with how much pressure is used and/or how fast the test is run.
The old low temperature viscosity test was basically a glorified pour test and didn't tell you much about how the oil would behave in a cold engine while it is cranking, or how it would pump.
There are two SAE J300 tests to determine low temperature viscosity. One is to determine the pumpability of the oil.The test method is designed to determine if an oil pump can pick the oil up and pump it. Pumpability is done 5 degrees colder than the cold cranking test, you don't want your engine to start if the pump can't supply oil.
The cold cranking test is done in a device that approximate how the oil gets sheared while an engine is cranking. There is a more force involved. If you want to look further, this looks like a good start...http://en.wikipedia.org/wiki/Cold-Cranking_Simulator
The viscosity of many liquids, oil included, vary with how much pressure is used and/or how fast the test is run.
The old low temperature viscosity test was basically a glorified pour test and didn't tell you much about how the oil would behave in a cold engine while it is cranking, or how it would pump.
There are two SAE J300 tests to determine low temperature viscosity. One is to determine the pumpability of the oil.The test method is designed to determine if an oil pump can pick the oil up and pump it. Pumpability is done 5 degrees colder than the cold cranking test, you don't want your engine to start if the pump can't supply oil.
The cold cranking test is done in a device that approximate how the oil gets sheared while an engine is cranking. There is a more force involved. If you want to look further, this looks like a good start...http://en.wikipedia.org/wiki/Cold-Cranking_Simulator
I think this is the Jell-O analogy you were looking for, from 2006:
Tom NJ
Originally Posted By: Tom NJ
Hi Madmike,
I would not trust any such formula. Pour point measures the temperature at which the oil stops pouring under its own weight, that is, under low shear conditions. In the engine, oils are sucked and pumped, which is much higher shear conditions and does not correlate to pour point. This is why the specifications call for CCS and MRV viscosity measurements instead of pour point.
Imagine a bowl of Jell-O. If you tilt the bowl, the Jell-O will wobble and perhaps sag a bit, but it does not flow out of the bowl like a liquid. This lack of flow would suggest that the Jell-O is a solid that would not flow where needed. Now take a spoon and stir, and the Jell-O will move fairly freely under the force (shear) of your hand. Then take wide straw and suck the Jell-O - again the Jell-O will flow up the straw under this vacuum force, but it will not flow back into fill the hole you sucked out. In other words, applying a force to an apparent solid material can cause it to flow and pump, even though it cannot do so under its own weight. The reason is that the Jell-O has a weak crystalline structure that breaks easily under force (shear) and reverts back to a liquid like substance that can be easily moved.
A similar situation exists with motor oils since mineral oils have waxes that grow crystals under certain temperature conditions, causing a "freeze point" as opposed to a "pour point". The difference is that "pouring" stops when the viscosity rises to a point that the oil is just too stiff to flow, while "freezing" occurs when the crystal structure from the waxes "knits" the oil into a weak solid, sort of like Jell-O. Crystal growth in oils requires a very slow cool down to occur, often with a pause or soak period. The pour point test cools at a relatively fast rate that can "super cool" the fluid, that is, it whizzes (technical term) right on past its freeze point and runs to its pour point, missing any freezing along the way.
The CCS test stirs the oil (applies shearing force) during the cool down and better simulates the shear rates of the oil pump than a simple pour point. The MRV test cools at a very slow rate with less shear and catches the effect of any freezing tendency.
Back in 1981 Quaker State had an oil that caused over 1,000 engines to seize due to these effects. The oil had a good pour point and CCS viscosity and could be readily sucked up and pumped by the oil pump when cold. However, their VI improver caused crystal growth under certain cooling conditions, turning the oil into a Jell-O like consistency in the pan. Then when the pump sucked the oil up from the reservoir in the pan, it created a hole and the oil was not able to flow back in and fill the hole. The pump then sucked air and the engines seized within minutes from oil starvation. This freezing phenomenon was prevalent and well documented in the Sioux Falls area where the temperatures during the failures cooled very slowly and paused for a while at about +10-15F. When simulated in the lab, the otherwise passing oil exhibited a freezing tendency. This temperature profile was referred to as the "Sioux Falls Cycle" and formed the basis of the cooling cycle used in the MRV test, which was then added to the J300 spec. QS owned up to the problem and paid the claims.
Tom
Tom NJ
Originally Posted By: Tom NJ
Hi Madmike,
I would not trust any such formula. Pour point measures the temperature at which the oil stops pouring under its own weight, that is, under low shear conditions. In the engine, oils are sucked and pumped, which is much higher shear conditions and does not correlate to pour point. This is why the specifications call for CCS and MRV viscosity measurements instead of pour point.
Imagine a bowl of Jell-O. If you tilt the bowl, the Jell-O will wobble and perhaps sag a bit, but it does not flow out of the bowl like a liquid. This lack of flow would suggest that the Jell-O is a solid that would not flow where needed. Now take a spoon and stir, and the Jell-O will move fairly freely under the force (shear) of your hand. Then take wide straw and suck the Jell-O - again the Jell-O will flow up the straw under this vacuum force, but it will not flow back into fill the hole you sucked out. In other words, applying a force to an apparent solid material can cause it to flow and pump, even though it cannot do so under its own weight. The reason is that the Jell-O has a weak crystalline structure that breaks easily under force (shear) and reverts back to a liquid like substance that can be easily moved.
A similar situation exists with motor oils since mineral oils have waxes that grow crystals under certain temperature conditions, causing a "freeze point" as opposed to a "pour point". The difference is that "pouring" stops when the viscosity rises to a point that the oil is just too stiff to flow, while "freezing" occurs when the crystal structure from the waxes "knits" the oil into a weak solid, sort of like Jell-O. Crystal growth in oils requires a very slow cool down to occur, often with a pause or soak period. The pour point test cools at a relatively fast rate that can "super cool" the fluid, that is, it whizzes (technical term) right on past its freeze point and runs to its pour point, missing any freezing along the way.
The CCS test stirs the oil (applies shearing force) during the cool down and better simulates the shear rates of the oil pump than a simple pour point. The MRV test cools at a very slow rate with less shear and catches the effect of any freezing tendency.
Back in 1981 Quaker State had an oil that caused over 1,000 engines to seize due to these effects. The oil had a good pour point and CCS viscosity and could be readily sucked up and pumped by the oil pump when cold. However, their VI improver caused crystal growth under certain cooling conditions, turning the oil into a Jell-O like consistency in the pan. Then when the pump sucked the oil up from the reservoir in the pan, it created a hole and the oil was not able to flow back in and fill the hole. The pump then sucked air and the engines seized within minutes from oil starvation. This freezing phenomenon was prevalent and well documented in the Sioux Falls area where the temperatures during the failures cooled very slowly and paused for a while at about +10-15F. When simulated in the lab, the otherwise passing oil exhibited a freezing tendency. This temperature profile was referred to as the "Sioux Falls Cycle" and formed the basis of the cooling cycle used in the MRV test, which was then added to the J300 spec. QS owned up to the problem and paid the claims.
Tom
I was doing a google search on MRV Viscosity to try and understand what the numbers on a PDS meant, when I came across this thread. I am basically trying to decide which Pen Ultra I want to buy while its on sale. I was looking at the product data sheets when I noticed....
5w30 - MRV 13000(-35) and CCS 5150(-35)
10w30 - MRV 10400(-30) and CCS 4570(-30)
What exactly does the 5w30 having higher numbers mean in "not so bright" terms? Does the higher numbers mean it is harder to pump at cold temps? Also, at what ambiant temperature should one start to take into consideration the MRV and CCS viscosities? I have always just used 0w30/5w30/0w40 oils, but I have read that the MRV and CCS viscosities are a more important stat to look at rather than 0w 5w 10w....etc
5w30 - MRV 13000(-35) and CCS 5150(-35)
10w30 - MRV 10400(-30) and CCS 4570(-30)
What exactly does the 5w30 having higher numbers mean in "not so bright" terms? Does the higher numbers mean it is harder to pump at cold temps? Also, at what ambiant temperature should one start to take into consideration the MRV and CCS viscosities? I have always just used 0w30/5w30/0w40 oils, but I have read that the MRV and CCS viscosities are a more important stat to look at rather than 0w 5w 10w....etc
hooligaqn24,
The MRV numbers cannot be compared directly. Notice that the measurements were done at two different temperatures.
The MRV numbers cannot be compared directly. Notice that the measurements were done at two different temperatures.
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What exactly does the 5w30 having higher numbers mean in "not so bright" terms?
In case you missed it, the higher numbers are at -5F lower in temp. At the same temp, that would not be true.
What exactly does the 5w30 having higher numbers mean in "not so bright" terms?
In case you missed it, the higher numbers are at -5F lower in temp. At the same temp, that would not be true.
well lets just say all 4 viscosity numbers stayed the same and all 4 temps were -35. Does that mean the lower number oil would pump easier?
Also, why would Pennzoil test the 10w30 to -30 and not -35? Is that the standard temp to test a 10w?
I have seen many times on this site where someone has said that the MRV #'s are more important to look at than just the 1st number of a multi viscosity oil. I am just trying to understand what to look for when choosing an oil by the MRV or CCS viscosities.
If any of you that have said that in the past and are reading this thread, what kind of numbers do you look for when choosing the oil by MRV Vis? and why do you choose those numbers?
Also, why would Pennzoil test the 10w30 to -30 and not -35? Is that the standard temp to test a 10w?
I have seen many times on this site where someone has said that the MRV #'s are more important to look at than just the 1st number of a multi viscosity oil. I am just trying to understand what to look for when choosing an oil by the MRV or CCS viscosities.
If any of you that have said that in the past and are reading this thread, what kind of numbers do you look for when choosing the oil by MRV Vis? and why do you choose those numbers?
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