Original Link:
http://www.ferrarichat.com/forum/showthread.php?t=136052
CAREFUL, it will make you want to get oil temp and pressure gauges. Ways to add them to your car at end of post.
I made an easier to understand version so it's a better read and the guy that wrote it was extremely repetitive and unorganized.
My Synopsis:
Chapter one - motor oil 101
The way motor oil is labeled is inherently misleading. Most people think a 0W-30 is too thin for an engine that recommends 10W-30. This is wrong. People think in terms of the oil thinning when it gets hot, they think this thinning with heat is the problem with motor oil. It is more correct to think that oil thickens when it cools and THIS is the problem. Oils are chosem by the mfr to give the right thickness at the normal operating temperature of the engine. Average everyday oil temp is 212F and on the track up to 302F. These two different operating temperatures require different oils.
We are dealing with a system of numbers that does not relate to the viscosity inside the can but at operating temp. The viscosity varies with temperature as well. A 30 weight oil has a viscosity of 3 at 302F and thickens to 10 at 212F. It further thickens to 100 at 104F and is too thick to measure at 32F. Engine designers usually call for their engines to run at 212F oil and water temperature with oil thickness of 10. This is the viscosity/thickness of the oil not the weight as labeled.
If the thickness of your oil when you got in your car this morning was 10 and after your commute was nearly done was 10, we'd live in perfectland. There would be little to no engine wear and tear. When you drove home from work that evening the car reached the correct operating temperature and the oil was a thickness of 10 - ideal. Overnight, the engine cooled to ambient temperature and the oil thickened. It's is now 75F and the oil thickness is around 150. It is too thick to lubricate an engine designed to run with an oil having a thickness of 10.
Now the concept of lubrication. Most believe pressure = lubrication, this is WRONG. Flow = lubrication. If pressure = lubrication then we would all use the heaviest oil possible. Lubrication is used to separate moving parts, to keep them from touching. There is a 1:1 relationship between flow and separation. Pressure and flow are in opposition. If you change your oil to a thicker formula the pressure will go up - there is more resistance to flow and flow must go down in order for pressure to go up. There is an inverse relationship. Thinner oil will cause pressure to go down, this occurs and flow is increased.
Example - Ferrari 575 Maranello driven around town. The manual states the target pressure is 75psi at 6,000RPM. The gold standard is that all engines should have a pressure of 10psi for every 1,000RPM. (10:1) You do need some pressure to move oil along, but only enough pressure, not more. More pressure is not better, it only results from the impedance of oil flow.
2.3L Oil Pressure Target per factory manual:
57-94 PSI @ 3,000 RPM
Ferrari is not saying what thickness of oil to use. That can only be determined by experimentation. In this situation oil temp is sitting around 185F around town on a hot Florida day. The thinnest API/SAE certified oil is Mobil 1's thinnest, even so the result is 80psi @ 2,000RPM. Is it too thick for the application (low temp low RPM) yet the thinnest oil money can buy. If on a hot Florida track mid-summer the oil temperature would probably get to 302F and the pressure would be about 40psi @ 6,000RPM - the oil is too thin for this application (high temp high RPM).
High flow does more than lubricate, it cools the hottest frictional parts of an engine.
Example and older 550 Maranello. It only specified 5W-40 Shell Helix Ultra as the oil to use in all conditions. This car was designed for racing. As it turns out Ferrari now recognizes that not every owner races their cars. The newer 575 now states 0W-40 for around town situations, 5W-40 for racing, and 10w-60 for hot climate racing. They now realize the difference between the daily urban driver and the very different racing situation.
Now when manuals call for 10W-30 a 0W-30 is always the better choice, ALWAYS. The 0W-30 is not thinner, it is the same thickness at operating temp as the 10W-30. The difference between them is when cold. As cooling occurs, the oils have gotten thicker, too thick to adequately lubricate the engine. The 10W thickened to a 90 and the 0W to about a 40. Both are too thick (more than the engine's desired 10) to do the job at this temperature. You are better starting off with a viscosity of 40 than 90.
People think in terms of the oil thinning when it gets hot, people SHOULD think that it thickens when it gets cold.
Chapter Two - motor oil 102
0W-30 and 10W-30 oils have the same thickness at operating temperature. The 0W-30 does not thicken as much when cooling occurs as opposed to the 10W-30.
Oil type.........Thickness at 75 F Thickness at 212 F
30 Weight......250......................10
10W-30.........100......................10
0W-30...........40.......................10
10 Weight......30........................6
The difference between the desired thickness your engine requires ( = 10 ) is closest to the 0W-30 oil at startup. It is still too thick for normal operation. But it does not have far to go before it warms up and thins to the correct viscosity. Remember that most engine wear occurs at startup when the oil is too thick to lubricate properly. It cannot flow and therefore cannot lubricate. Most of the thick oil at startup actually goes through the bypass valve back to the engine oil sump and not into your engine oil ways. This is especially true when you really step on that gas pedal. You really need more lubrication and you actually get less.
Note that a straight 10 weight oil is also too thick for your engine at startup - thickness of 30. At operating temperatures it is too thin having a thickness of 6. It needs to be around 10. The oil companies have added viscosity index improvers or VI to oils to solve this dilemma. They take a mineral based oil and add VI improvers so that it does not thin as as much when it gets hotter. Now instead of only having a thickness of 6 when hot it has a thickness of 10, just as we need.
The penalty is the startup thickness also goes up to 100. It's better than being up at 250 as a straight 30 weight oil though. Oil with a startup thickness of 100 that becomes the appropriate thickness of 10 when fully warmed up is called a 10W-30 weight motor oil. This is NOT as thick as a straight 30 weight oil at startup and it is NOT as thin as a straight 10 weight oil at full operating temperature.
The downside of a mineral based multigrade oil is that this VI additive wears out over time and you end up with the original straight 10 weight oil. It will go back to being too thin when hot. It will have a thickness of 6 instead of 10 at operating temperature. This may be why Porsche does not want a 0W-30 but rather a 10W-30. If the VI wears out the mineral 0W-30 will ultimately be thinner, a straight 0 weight oil. When the VI is used up in the 10W-30 oil it too is thinner. It goes back to a straight 10 weight oil. They are both still too thick at startup, both of them. The straight 0 weight oil, a 5 weight oil, and a 10 weight oil are all too thick at startup.
With normal oil change intervals the VI improver will not wear out and so the problem does not really exist. In fact, oils do thin a little with use. What is more interesting is that with further use motor oils actually thicken and this is much worse than the minimal thinning that may have occurred earlier.
Synthetic oils are a whole different story. There is no VI improver added so there is nothing to wear out. The actual oil molecules never wear out. You could almost use the same oil forever. The problem is that there are other additives and they do get used up. I suppose if there was a good way to keep oil clean you could just add a can of additives every 6 months and just change the filter, never changing the oil.
When the additives wear out in a synthetic oil it still has the same viscosity. These oils will always have the correct thickness when hot and will still be too thick at startup as with all oils of all types, regardless of the API / SAE viscosity rating.
Automotive engine manufacturers know there is thinning or thickening that will occur. They take these things into account when they write that owners manual. The reality is that motor oils limit is both time itself (with no motor use) and/or mileage use.
http://www.ferrarichat.com/forum/showthread.php?t=136052
CAREFUL, it will make you want to get oil temp and pressure gauges. Ways to add them to your car at end of post.
I made an easier to understand version so it's a better read and the guy that wrote it was extremely repetitive and unorganized.
My Synopsis:
Chapter one - motor oil 101
The way motor oil is labeled is inherently misleading. Most people think a 0W-30 is too thin for an engine that recommends 10W-30. This is wrong. People think in terms of the oil thinning when it gets hot, they think this thinning with heat is the problem with motor oil. It is more correct to think that oil thickens when it cools and THIS is the problem. Oils are chosem by the mfr to give the right thickness at the normal operating temperature of the engine. Average everyday oil temp is 212F and on the track up to 302F. These two different operating temperatures require different oils.
We are dealing with a system of numbers that does not relate to the viscosity inside the can but at operating temp. The viscosity varies with temperature as well. A 30 weight oil has a viscosity of 3 at 302F and thickens to 10 at 212F. It further thickens to 100 at 104F and is too thick to measure at 32F. Engine designers usually call for their engines to run at 212F oil and water temperature with oil thickness of 10. This is the viscosity/thickness of the oil not the weight as labeled.
If the thickness of your oil when you got in your car this morning was 10 and after your commute was nearly done was 10, we'd live in perfectland. There would be little to no engine wear and tear. When you drove home from work that evening the car reached the correct operating temperature and the oil was a thickness of 10 - ideal. Overnight, the engine cooled to ambient temperature and the oil thickened. It's is now 75F and the oil thickness is around 150. It is too thick to lubricate an engine designed to run with an oil having a thickness of 10.
Now the concept of lubrication. Most believe pressure = lubrication, this is WRONG. Flow = lubrication. If pressure = lubrication then we would all use the heaviest oil possible. Lubrication is used to separate moving parts, to keep them from touching. There is a 1:1 relationship between flow and separation. Pressure and flow are in opposition. If you change your oil to a thicker formula the pressure will go up - there is more resistance to flow and flow must go down in order for pressure to go up. There is an inverse relationship. Thinner oil will cause pressure to go down, this occurs and flow is increased.
Example - Ferrari 575 Maranello driven around town. The manual states the target pressure is 75psi at 6,000RPM. The gold standard is that all engines should have a pressure of 10psi for every 1,000RPM. (10:1) You do need some pressure to move oil along, but only enough pressure, not more. More pressure is not better, it only results from the impedance of oil flow.
2.3L Oil Pressure Target per factory manual:
57-94 PSI @ 3,000 RPM
Ferrari is not saying what thickness of oil to use. That can only be determined by experimentation. In this situation oil temp is sitting around 185F around town on a hot Florida day. The thinnest API/SAE certified oil is Mobil 1's thinnest, even so the result is 80psi @ 2,000RPM. Is it too thick for the application (low temp low RPM) yet the thinnest oil money can buy. If on a hot Florida track mid-summer the oil temperature would probably get to 302F and the pressure would be about 40psi @ 6,000RPM - the oil is too thin for this application (high temp high RPM).
High flow does more than lubricate, it cools the hottest frictional parts of an engine.
Example and older 550 Maranello. It only specified 5W-40 Shell Helix Ultra as the oil to use in all conditions. This car was designed for racing. As it turns out Ferrari now recognizes that not every owner races their cars. The newer 575 now states 0W-40 for around town situations, 5W-40 for racing, and 10w-60 for hot climate racing. They now realize the difference between the daily urban driver and the very different racing situation.
Now when manuals call for 10W-30 a 0W-30 is always the better choice, ALWAYS. The 0W-30 is not thinner, it is the same thickness at operating temp as the 10W-30. The difference between them is when cold. As cooling occurs, the oils have gotten thicker, too thick to adequately lubricate the engine. The 10W thickened to a 90 and the 0W to about a 40. Both are too thick (more than the engine's desired 10) to do the job at this temperature. You are better starting off with a viscosity of 40 than 90.
People think in terms of the oil thinning when it gets hot, people SHOULD think that it thickens when it gets cold.
Chapter Two - motor oil 102
0W-30 and 10W-30 oils have the same thickness at operating temperature. The 0W-30 does not thicken as much when cooling occurs as opposed to the 10W-30.
Oil type.........Thickness at 75 F Thickness at 212 F
30 Weight......250......................10
10W-30.........100......................10
0W-30...........40.......................10
10 Weight......30........................6
The difference between the desired thickness your engine requires ( = 10 ) is closest to the 0W-30 oil at startup. It is still too thick for normal operation. But it does not have far to go before it warms up and thins to the correct viscosity. Remember that most engine wear occurs at startup when the oil is too thick to lubricate properly. It cannot flow and therefore cannot lubricate. Most of the thick oil at startup actually goes through the bypass valve back to the engine oil sump and not into your engine oil ways. This is especially true when you really step on that gas pedal. You really need more lubrication and you actually get less.
Note that a straight 10 weight oil is also too thick for your engine at startup - thickness of 30. At operating temperatures it is too thin having a thickness of 6. It needs to be around 10. The oil companies have added viscosity index improvers or VI to oils to solve this dilemma. They take a mineral based oil and add VI improvers so that it does not thin as as much when it gets hotter. Now instead of only having a thickness of 6 when hot it has a thickness of 10, just as we need.
The penalty is the startup thickness also goes up to 100. It's better than being up at 250 as a straight 30 weight oil though. Oil with a startup thickness of 100 that becomes the appropriate thickness of 10 when fully warmed up is called a 10W-30 weight motor oil. This is NOT as thick as a straight 30 weight oil at startup and it is NOT as thin as a straight 10 weight oil at full operating temperature.
The downside of a mineral based multigrade oil is that this VI additive wears out over time and you end up with the original straight 10 weight oil. It will go back to being too thin when hot. It will have a thickness of 6 instead of 10 at operating temperature. This may be why Porsche does not want a 0W-30 but rather a 10W-30. If the VI wears out the mineral 0W-30 will ultimately be thinner, a straight 0 weight oil. When the VI is used up in the 10W-30 oil it too is thinner. It goes back to a straight 10 weight oil. They are both still too thick at startup, both of them. The straight 0 weight oil, a 5 weight oil, and a 10 weight oil are all too thick at startup.
With normal oil change intervals the VI improver will not wear out and so the problem does not really exist. In fact, oils do thin a little with use. What is more interesting is that with further use motor oils actually thicken and this is much worse than the minimal thinning that may have occurred earlier.
Synthetic oils are a whole different story. There is no VI improver added so there is nothing to wear out. The actual oil molecules never wear out. You could almost use the same oil forever. The problem is that there are other additives and they do get used up. I suppose if there was a good way to keep oil clean you could just add a can of additives every 6 months and just change the filter, never changing the oil.
When the additives wear out in a synthetic oil it still has the same viscosity. These oils will always have the correct thickness when hot and will still be too thick at startup as with all oils of all types, regardless of the API / SAE viscosity rating.
Automotive engine manufacturers know there is thinning or thickening that will occur. They take these things into account when they write that owners manual. The reality is that motor oils limit is both time itself (with no motor use) and/or mileage use.
Last edited: