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I nearly agree except we have to be careful using words like "always."
For example, one of the issues in the Ford Explorer rollover scandal was that, to improve ride comfort, Ford engineers specified lower tire air pressures than those recommended by Firestone. The resulting increase in tire heat is thought to have contributed to the increased rate of tread separation. So at least in that case, the supplier's spec probably should have trumped the automaker's.
But other than isolated cases like that, I agree with you, Mikey!
"recommended by Jaguar." I don't care what you say, because your main point in this forum is come into every threat regarding oil, coolant, air filter to read Jaguar manual ss a some kind of bible. 10W-60 is great oil for summer use in high tune supercharged engine when you push hard - track, drag race, 200miles autobahn driving at 130mph+ and it also works great in normal use. Liqui Moly 10-60 oil, Evans waterless coolant and RVS Technology engine products are all great stuff.
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BTW, the funny thing is that 10W60 is also the specified oil when the SAME engine
is installed in an Aston Martin.
So, 5W30 for Jaguar owners, 10W60 for Aston Martin owners.
Guess AM figured their owners could afford the good stuff.
I nearly agree except we have to be careful using words like "always."
For example, one of the issues in the Ford Explorer rollover scandal was that, to improve ride comfort, Ford engineers specified lower tire air pressures than those recommended by Firestone. The resulting increase in tire heat is thought to have contributed to the increased rate of tread separation. So at least in that case, the supplier's spec probably should have trumped the automaker's.
But other than isolated cases like that, I agree with you, Mikey!
BTW, the funny thing is that 10W60 is also the specified oil when the SAME engine
is installed in an Aston Martin.
So, 5W30 for Jaguar owners, 10W60 for Aston Martin owners.
Guess AM figured their owners could afford the good stuff.
++
AM was most likely compensating for higher oil temperatures which would account for oil thinning. Personally anything over a 40wt oil would be a waste in my car especially at this time of the year. It isn't driven long distances and the oil barely makes it to operating temp.
I have used the Castrol 10w60 in the summer as well, and have now switched to my beloved 0w40 from M1 for the winter months. I choose to use the 10w60 for more protection as it has higher hths values, for just in case. I wouldn’t want to go lower than the hths value of the 0w40 from m1 has, and that one has served me very well in the past with my elevated power levels. I wouldn't necessarily go for a 10w60 on a standard car, but then again, a more worn out engine and very sportive driving might benefit from higher viscosity oil/hths values for longevity, as said I would not go lower than the 0w40 M1 at least.
You need very strong justifications to drift from manufacturer recommended viscosities. You will degrade original engine capabilities as a minimum, and particularly if you have 4.2 upgraded cam-lifted engine (started somewhere from 2006-7MY you will kill you VVT or how Jag calls it because of low throughput resulted in oil starvation in this very hydraulic precise mechanism. The "ideal" oil for engine is thin like water and strong like carbon and capable of keeping such condition in very wide temperature range, say from -30 to +130С. But this only possible by warner brothers in 2015.. lets wait for more 20-30 years to see if chemistry and technologies can achieve it..
Engine worn is also not a flag for changing viscosity as well as oil consumption. Stock engine is a balanced system, you will "improve" here and inevitably lose there.
Clue: Just use recommended viscosity of ANY manufacturer you like, really, and if you anyway need "to do something better" with you car just shorter oil change intervals.
if you have 4.2 upgraded cam-lifted engine (started somewhere from 2006-7MY you will kill you VVT or how Jag calls it because of low throughput resulted in oil starvation in this very hydraulic precise mechanism.
Wouldn't know if it would kill it, but I agree on not trying here ;-)
It would be equally valid to speculate that AM has a different
viewpoint as to end use, CAFE requirements, and the list goes
on.
It's safe to speculate an AM would be more likely to be driven harder than an XJ. I'm much more sedate of a driver in my VDP than I was in my previous muscle and sports cars. I ran 0W40 in my GTO to compensate for the hotter temps for driving it harder. Anything heavier than a 40wt in a modern car unless otherwise specified is over kill. I had one run of 15W50 in the GTO and even when pushed extremely hard and the oil was good and hot, the pressure was unnecessarily high.
Understanding modern oils, and the way in which the chemistry works, is the starting point in determining usage. A 0w40 for example, starts as a 0 weight stock, and viscosity improvers are added, (think of them as a slinky) and as temperature rises the molecules expand to create a higher viscosity. As the oil is sheared, the ability of the molecules to return to it's original state is reduced and the oil retains it's heavier viscosity. Find an appropriate low viscosity point to match the average temperature for the area in which you drive. Higher viscosity ratings (like a 10w60) can be detrimental to proper flow at lower RPM to critical engine components like VVT for example, especially when temps are in sub-zero environment.
Also, if someone can point me to definitive proof of a modern Jaguar V8 failing due to using the recommended oil viscosity where the oil pump didn't fail, I may be swayed away from 5w30 and 0w40. It just doesn't happen these days.
Also, if someone can point me to definitive proof of a modern Jaguar V8 failing due to using the recommended oil viscosity where the oil pump didn't fail, I may be swayed away from 5w30 and 0w40. It just doesn't happen these days.
This is the basis of my confusion with the never-ending oil debates. Engine lubrication issues while following OEM recommendations for type, viscosity and change interval are essentially unheard of. There are no known problems that need to be fixed.
The penalty for attempting to fix something that is not broken might be zero, or might be a prematurely worn or failed engine. Either way, nothing is gained.
Understanding modern oils, and the way in which the chemistry works, is the starting point in determining usage. A 0w40 for example, starts as a 0 weight stock, and viscosity improvers are added, (think of them as a slinky) and as temperature rises the molecules expand to create a higher viscosity.
To that statement I would add, "...a higher viscosity compared to a monograde oil of the same grade as the multigrade oil's low-temperature grade."
The topic of viscosity improvers, or more correctly, Viscosity Index improvers, is interesting and appears to be commonly misunderstood or misrepresented, even in oil company literature. And as to the oft-repeated Slinky analogy, well, more on that later.
Most JF members already know what I'm about to present, but given all the incorrect information online, this discussion has inspired me to try to collect some info into a single post for the benefit of those who may still struggle to understand how multigrade oils "work."
Viscosity vs. Temperature
A multigrade oil is represented by two numbers with the letter "W" or "w" after the first number, and sometimes a hyphen or dash before the second number. For example, 10W30, 10w30 or 10W-30. In this example, 10W is the oil's low-temperature or "Winter" grade, and 30 is the oil's high-temperature or "Summer" grade.
The absolute (or "dynamic") viscosity of a multigrade oil does not actually increase at higher temperatures, but rather decreases less than that of a monograde oil of the same grade as the multigrade oil's low-temp grade (e.g. "10W").
At the other end, the high-temp viscosity of a multigrade oil is similar to that of a monograde oil of the same grade (e.g. "30") at standard test temperatures (40C/ 104F (ISO) or 100C/210F (SAE)).
To put it simply, 10W30 oil flows like 10 grade oil at low temperatures, but protects like 30 grade oil at high temperatures.
But that doesn't mean 10W30 oil is "thicker" at high temps than at low ones, as is sometimes incorrectly stated or implied, even by some petrochemical companies:
Just as monograde 30-weight oil is "thinner" or less viscous at 100C than at -20C, so also is 10W30.
Note: as the Machinery Lubrication website puts it, "Stating an oil's viscosity is meaningless unless the temperature at which the viscosity is measured is defined."
Viscosity Index Improvers
As their name implies, Viscosity Index improvers or modifiers increase the Viscosity Index of a multigrade oil, meaning that its modified viscosity varies less with temperature compared to a monograde oil with the same base viscosity. At low temperatures, the viscosity of 10W30 oil is equal to that of 10 grade oil, but at higher temperatures, its viscosity does not decrease as much as 10 grade oil but instead decreases only to the degree that 30 grade oil does at the same temp. The chart below illustrates this phenomenon:
The high-temp and low-temp ratings of multigrade oils are tested differently and therefore cannot be directly compared:
The high-temp or "Summer" rating is based on simple Kinematic Viscosity at 40C and 100C (low shear viscosity). Kinematic viscosity is a measure of an oil's resistance to flow and shear due to gravity, or simply, "how quickly it will pour" at a given temperature.
High Shear High Temperature (HSHT) viscosity is measured at 150C.
The low-temp or "Winter" rating is based on performance in a cold-cranking simulator which determines the "Apparent Viscosity," plus the borderline pumpability temperature (BPT), which is a measure of the lowest temperature at which an engine oil can be continuously and adequately supplied to the components of an automotive engine at a standard pressure of 60,000 mPa (per SAE J300 and various ASTM testing procedures).
The link below explains the SAE grading standards. Note the chart of gear oil weights that illustrates the actual viscosity of monograde oils at 100C compared to their SAE grade. For example, the actual minimum viscosity of 70W oil at 100C is just 3.72!
Viscosity Index is a unitless number determined by comparing the oil under test to two reference oils, one with a VI of 0 and the other with a VI of 100. The chart below illustrates that an oil with a smaller change in kinematic viscosity with temperature will have a higher VI than an oil with a greater viscosity change across the same temperature range:
Regarding the popular Slinky analogy, since 1958* the "expanding polymer coil" theory has reflected the limited understanding of VI improver function and has been widely repeated, even by manufacturers of VI improvers. The Slinky analogy has come to be probably the most common means of explaining this theoretical mechanism. But at the link below is an interesting research paper, submitted for publication January 2015 and first published in March, which explores and challenges that long-accepted theory. Through the use of Small Angle Neutron Scattering and rheological measurements, the authors found that the molecules of some polymers commonly used as VI improvers do not appreciably "expand" with rising temperature, and that some even "decrease" in "size", yet still manage to improve VI:
For those who don't want to read a scientific paper, I'll leave you with this tantalizing quote:
"It has been shown in section 3.1 that the intrinsic viscosity of polymeric viscosity modifiers undergoes a slight
decrease or increase with temperature, depending upon polymer chemistry. Combining intrinsic viscosity and
SANS results, it is clear that the radius of gyration or polymer coil size in solution is relatively invariant with
temperature, especially for OCP. If the polymer does not expand as temperature increases, how can one explain
the well-known observation that OCP polymers increase the viscosity index of lubricating oils?"
Cheers,
Don
*T.W. Selby, "The Non-Newtonian Characteristics of Lubricating Oils," 1958
To that statement I would add, "...a higher viscosity compared to a monograde oil of the same grade as the multigrade oil's low-temperature grade." [snip]
You aren't perhaps a BITOG member as well, are you?
I think the key question should be more on how well an oil can perform i.e. protect your engine. Although I can see the value to know how fast an oil flows down a funnel at a certain temp (viscosity), the hths test and value looks more interesting in terms to the oils ability to protect. Interestingly enough there seems a correlation between the viscosity and the hths value.
Anyway, I understand that hths alone is not a figure to go for (i.e. to just take the highest value).
As there was no spec for tuned engines from Jaguar, I became more interested in higher hths values than the 3.7 that m1 0w40 offered, even at the cost of fuel economy/power ;-)
PS the AM V8 engines also used VVT, but I don’t know if the unit used was the same as on Jaguars.
To that statement I would add, "...a higher viscosity compared to a monograde oil of the same grade as the multigrade oil's low-temperature grade."
The topic of viscosity improvers, or more correctly, Viscosity Index improvers, is interesting and appears to be commonly misunderstood or misrepresented, even in oil company literature. And as to the oft-repeated Slinky analogy, well, more on that later.
Most JF members already know what I'm about to present, but given all the incorrect information online, this discussion has inspired me to try to collect some info into a single post for the benefit of those who may still struggle to understand how multigrade oils "work."
Viscosity vs. Temperature
A multigrade oil is represented by two numbers with the letter "W" or "w" after the first number, and sometimes a hyphen or dash before the second number. For example, 10W30, 10w30 or 10W-30. In this example, 10W is the oil's low-temperature or "Winter" grade, and 30 is the oil's high-temperature or "Summer" grade.
The absolute (or "dynamic") viscosity of a multigrade oil does not actually increase at higher temperatures, but rather decreases less than that of a monograde oil of the same grade as the multigrade oil's low-temp grade (e.g. "10W").
At the other end, the high-temp viscosity of a multigrade oil is similar to that of a monograde oil of the same grade (e.g. "30") at standard test temperatures (40C/ 104F (ISO) or 100C/210F (SAE)).
To put it simply, 10W30 oil flows like 10 grade oil at low temperatures, but protects like 30 grade oil at high temperatures.
But that doesn't mean 10W30 oil is "thicker" at high temps than at low ones, as is sometimes incorrectly stated or implied, even by some petrochemical companies:
Just as monograde 30-weight oil is "thinner" or less viscous at 100C than at -20C, so also is 10W30.
Note: as the Machinery Lubrication website puts it, "Stating an oil's viscosity is meaningless unless the temperature at which the viscosity is measured is defined."
Viscosity Index Improvers
As their name implies, Viscosity Index improvers or modifiers increase the Viscosity Index of a multigrade oil, meaning that its modified viscosity varies less with temperature compared to a monograde oil with the same base viscosity. At low temperatures, the viscosity of 10W30 oil is equal to that of 10 grade oil, but at higher temperatures, its viscosity does not decrease as much as 10 grade oil but instead decreases only to the degree that 30 grade oil does at the same temp. The chart below illustrates this phenomenon:
The high-temp and low-temp ratings of multigrade oils are tested differently and therefore cannot be directly compared:
The high-temp or "Summer" rating is based on simple Kinematic Viscosity at 40C and 100C (low shear viscosity). Kinematic viscosity is a measure of an oil's resistance to flow and shear due to gravity, or simply, "how quickly it will pour" at a given temperature.
High Shear High Temperature (HSHT) viscosity is measured at 150C.
The low-temp or "Winter" rating is based on performance in a cold-cranking simulator which determines the "Apparent Viscosity," plus the borderline pumpability temperature (BPT), which is a measure of the lowest temperature at which an engine oil can be continuously and adequately supplied to the components of an automotive engine at a standard pressure of 60,000 mPa (per SAE J300 and various ASTM testing procedures).
The link below explains the SAE grading standards. Note the chart of gear oil weights that illustrates the actual viscosity of monograde oils at 100C compared to their SAE grade. For example, the actual minimum viscosity of 70W oil at 100C is just 3.72!
Viscosity Index is a unitless number determined by comparing the oil under test to two reference oils, one with a VI of 0 and the other with a VI of 100. The chart below illustrates that an oil with a smaller change in kinematic viscosity with temperature will have a higher VI than an oil with a greater viscosity change across the same temperature range:
Regarding the popular Slinky analogy, since 1958* the "expanding polymer coil" theory has reflected the limited understanding of VI improver function and has been widely repeated, even by manufacturers of VI improvers. The Slinky analogy has come to be probably the most common means of explaining this theoretical mechanism. But at the link below is an interesting research paper, submitted for publication January 2015 and first published in March, which explores and challenges that long-accepted theory. Through the use of Small Angle Neutron Scattering and rheological measurements, the authors found that the molecules of some polymers commonly used as VI improvers do not appreciably "expand" with rising temperature, and that some even "decrease" in "size", yet still manage to improve VI:
For those who don't want to read a scientific paper, I'll leave you with this tantalizing quote:
"It has been shown in section 3.1 that the intrinsic viscosity of polymeric viscosity modifiers undergoes a slight
decrease or increase with temperature, depending upon polymer chemistry. Combining intrinsic viscosity and
SANS results, it is clear that the radius of gyration or polymer coil size in solution is relatively invariant with
temperature, especially for OCP. If the polymer does not expand as temperature increases, how can one explain
the well-known observation that OCP polymers increase the viscosity index of lubricating oils?"
Cheers,
Don
*T.W. Selby, "The Non-Newtonian Characteristics of Lubricating Oils," 1958
Also noted in the same paper, "Although we have shown that the polymer coil expansion model of Selby is not a required mechanism to explain how polymers increase the viscosity index of lubricating oils, it can enhance the effect. (of explanation) "
12-09-2015, 10:04 PM
