On one hand you say that synthetics have a lower coefficient of friction, and on the other you say that synthetics have a higher resistance to shear.
Oil Rheology III - What's the Lubricant?
- Thread starter MolaKule
- Start date
- Status
MolaKule
Staff member
No I said synthetics produce (or allow) a lower coeficient of friction [between two surfaces was implied]. It is this shear resistance that gives allows reduced friction.
If the oil sheared, the viscosity would drop, and the two metal surfaces would come into contact or partial contact, with the result that friction would increase, giving rise to the friction coefficient.
Now increase shear strength of the oil, and the localized viscosity separates the two surfaces, effectively lowering the kinetic coefficient of friction.
[ September 27, 2003, 10:55 AM: Message edited by: MolaKule ]
If the oil sheared, the viscosity would drop, and the two metal surfaces would come into contact or partial contact, with the result that friction would increase, giving rise to the friction coefficient.
Now increase shear strength of the oil, and the localized viscosity separates the two surfaces, effectively lowering the kinetic coefficient of friction.
[ September 27, 2003, 10:55 AM: Message edited by: MolaKule ]
Implied, but not stated. Lawers like to disect the first word.
Now as I understand it, if you reduce the shear strength of a fluid, you also reduce its resistance to flow.
You have this room full of golf balls piled to the ceiling. You ask your friend to go into the room because you have a surprise waiting for him.
He opens the door and is instantally buried by the golf balls. "Surprise".
The golf balls have no viscosity.
OOoooohhhhmmmmmmmmm, Quiet, I'm meditating.
Now as I understand it, if you reduce the shear strength of a fluid, you also reduce its resistance to flow.
You have this room full of golf balls piled to the ceiling. You ask your friend to go into the room because you have a surprise waiting for him.
He opens the door and is instantally buried by the golf balls. "Surprise".
The golf balls have no viscosity.
OOoooohhhhmmmmmmmmm, Quiet, I'm meditating.
I was under the impression that, since petroleum multigrade oils are created using VII's, they suffer a temporary viscosity drop when under shear, resulting in lower viscous drag in parts of the engine. A monograde oil does not suffer this temporary drop, so drag is not reduced.
What about synthetic multigrades that are created without VII's? Do they have the same friction characteristisc, under shear, as monogrades?
Do synthetics, then, have to be made on the low end of the viscosity scale in order to pass the fuel economy tests?
What about synthetic multigrades that are created without VII's? Do they have the same friction characteristisc, under shear, as monogrades?
Do synthetics, then, have to be made on the low end of the viscosity scale in order to pass the fuel economy tests?
MolaKule
Staff member
Oilyriser,
In reality, there is no such thing as a full synthetic monograde - take a look at Redline's specs for their monograde racing oils, as an example. Esters and PAO mixes have high VI's without any VII's.
Many synthetics are made of differing viscosities of various base oils. Most synthetic oils bases are binary or ternary mixes of various viscosity bases.
[ October 06, 2003, 11:11 AM: Message edited by: MolaKule ]
In reality, there is no such thing as a full synthetic monograde - take a look at Redline's specs for their monograde racing oils, as an example. Esters and PAO mixes have high VI's without any VII's.
Many synthetics are made of differing viscosities of various base oils. Most synthetic oils bases are binary or ternary mixes of various viscosity bases.
[ October 06, 2003, 11:11 AM: Message edited by: MolaKule ]
How about........The new group II+ mono-grade engine oils likely have VIs high enough to pass a non-standard multi-grade test.
This could be an SAE 30 group II+ engine oil passing a 25W, 20W, or 15W cold flow and cranking test.
Although these engine oils are not labeled or marketed as multi-grades, they fit the description of a multi-grade lubricant.
...An engine oil, fluid, or lubricant that passes more than one SAE viscosity grade test requirement.
In actual engine operation, it has been stated in these threads, that a multi-grade engine oil, whether or not containing VI improvers, act as multi-grades.
If that statment is true, then the SAE paper written X number of years ago is either obsolete, or only refers to low VI (group I) mono-grade engine oils.
In brackets ( ), means implied, but not stated.
[ October 07, 2003, 01:06 AM: Message edited by: userfriendly ]
This could be an SAE 30 group II+ engine oil passing a 25W, 20W, or 15W cold flow and cranking test.
Although these engine oils are not labeled or marketed as multi-grades, they fit the description of a multi-grade lubricant.
...An engine oil, fluid, or lubricant that passes more than one SAE viscosity grade test requirement.
In actual engine operation, it has been stated in these threads, that a multi-grade engine oil, whether or not containing VI improvers, act as multi-grades.
If that statment is true, then the SAE paper written X number of years ago is either obsolete, or only refers to low VI (group I) mono-grade engine oils.
In brackets ( ), means implied, but not stated.
[ October 07, 2003, 01:06 AM: Message edited by: userfriendly ]
MolaKule
Staff member
Hey Mr. Monograde
I suggest you write to the SAE and API and have them change them there classifications.
[ October 07, 2003, 05:20 PM: Message edited by: MolaKule ]
[ October 07, 2003, 05:20 PM: Message edited by: MolaKule ]
Right after M-TV starts playing classical.
To solve the mono-grade friction question, they could have ran the engine at various working rates and measured the fuel use.
Other than improved fuel economy during the warm-up cycle,
do multi grade lubricants improve fuel economy compared to mono grades during constant high load operation?
Would a 5W30 be more economic than an SAE 30 at constant high load operation?
And of course, those multi grade lubricants would have to contain VIIs to satisfy the description implied if not stated in the above thread.
According to all of the above, VIIs improve fuel economy by reducing friction in the piston ring pack, and not the fact that the lubricant is a multi-grade.
Other than improved fuel economy during the warm-up cycle,
do multi grade lubricants improve fuel economy compared to mono grades during constant high load operation?
Would a 5W30 be more economic than an SAE 30 at constant high load operation?
And of course, those multi grade lubricants would have to contain VIIs to satisfy the description implied if not stated in the above thread.
According to all of the above, VIIs improve fuel economy by reducing friction in the piston ring pack, and not the fact that the lubricant is a multi-grade.
Bearing and piston friction have to do with the HTHS side of the oil performance...and HTHS was pretty irrelevant prior to VII giving a certain viscosity at low shear rates, and becoming somewhat thinner at high shear rates.
HTHS was introduced as a minumum requirement so that (in the words of SAE), an oil marketted as a grade would not undergo temporary shearing to the point that engine damage occurred.
So yes, a "typical" 30 multigrade, with HTHS around 3 as an example will provide better economy than a straight 30. (in response to a few posts up in the thread, a synthetic oil with no VIIs, that displays Newtonian characteristics under different shear rate can be labeled SAE 30 and/or xW-30 depending on the producer's choice...can't add polymers and call it a 30).
There's a (IIRC) Honda paper kicking around where they chose a number of straight weights of various viscosities to represent the changing behaviours of multigrades under high shear...e.g. a monograde 20 to simulate the High shear behaviour of a multigrade 30.
HTHS was introduced as a minumum requirement so that (in the words of SAE), an oil marketted as a grade would not undergo temporary shearing to the point that engine damage occurred.
So yes, a "typical" 30 multigrade, with HTHS around 3 as an example will provide better economy than a straight 30. (in response to a few posts up in the thread, a synthetic oil with no VIIs, that displays Newtonian characteristics under different shear rate can be labeled SAE 30 and/or xW-30 depending on the producer's choice...can't add polymers and call it a 30).
There's a (IIRC) Honda paper kicking around where they chose a number of straight weights of various viscosities to represent the changing behaviours of multigrades under high shear...e.g. a monograde 20 to simulate the High shear behaviour of a multigrade 30.
Here's the paper
https://www.hondarandd.jp/point.php?pid=72&lang=en
"Effects of Low-viscosity Engine Oil on Fuel Economy and Wear"
https://www.hondarandd.jp/point.php?pid=72&lang=en
"Effects of Low-viscosity Engine Oil on Fuel Economy and Wear"
Pretty much confirming what we know here, at least a few of us.
Low viscosity doesn't hurt a thing if the basics are kept in line.
Low viscosity doesn't hurt a thing if the basics are kept in line.
This is what happened that sparked my curiosity and sent me searching that wound up here;
Last September I tried a 10W40 PCMO in my 2011 Duramax. The 1st month I put 3,600 miles on the truck. I scaled it once at 9,400 lbs, so it was not running around empty.
I figured that the 10W40 PCMO saved enough fuel over a 15W40 base line in 5,000 miles, to pay for the oil and filter.
At 7,600 miles in March I changed the oil and took a sample of the 10W40 PCMO in for a UOA.
Everything was OK except the viscosity at 100C had dropped from a new sample I provided of 15.4 to around 11.6. The 40C viscosity dropped from 105 to 88.
If VIIs in the 10W40 was the reason for the fuel economy improvement, then once that additive has permanently sheared the oil should act like a mono grade.
In the above case, a poor quality SAE 30, instead of the original 10W40.
Next question; High VI lubricants are as stated in the above thread (sans spell check),as natural multi-grades.
My guess is that those high VI lubricants that do not need VII to achieve a multi-grade classification, but contain some sort of additive that acts like a VII. That new additive is quite likely sacrificed, sheared or lost in translation over the duty cycle of the lubricant.
If all or any of what I just wrote is true, then extending drain intervals may not be economical.
What little you may save in oil, you spend much more in fuel.
It would be interesting to see a test in pounds of fuel used per horsepower hour, or the metric equivalent, and wear rates change when a lubricant is run past its intended life.
My opinion of SAE in seven seconds or less?
I think it is time to throw away Daddy's teddy bears.
Last September I tried a 10W40 PCMO in my 2011 Duramax. The 1st month I put 3,600 miles on the truck. I scaled it once at 9,400 lbs, so it was not running around empty.
I figured that the 10W40 PCMO saved enough fuel over a 15W40 base line in 5,000 miles, to pay for the oil and filter.
At 7,600 miles in March I changed the oil and took a sample of the 10W40 PCMO in for a UOA.
Everything was OK except the viscosity at 100C had dropped from a new sample I provided of 15.4 to around 11.6. The 40C viscosity dropped from 105 to 88.
If VIIs in the 10W40 was the reason for the fuel economy improvement, then once that additive has permanently sheared the oil should act like a mono grade.
In the above case, a poor quality SAE 30, instead of the original 10W40.
Next question; High VI lubricants are as stated in the above thread (sans spell check),as natural multi-grades.
My guess is that those high VI lubricants that do not need VII to achieve a multi-grade classification, but contain some sort of additive that acts like a VII. That new additive is quite likely sacrificed, sheared or lost in translation over the duty cycle of the lubricant.
If all or any of what I just wrote is true, then extending drain intervals may not be economical.
What little you may save in oil, you spend much more in fuel.
It would be interesting to see a test in pounds of fuel used per horsepower hour, or the metric equivalent, and wear rates change when a lubricant is run past its intended life.
My opinion of SAE in seven seconds or less?
I think it is time to throw away Daddy's teddy bears.
MolaKule
Staff member
Quote:
My guess is that those high VI lubricants that do not need VII to achieve a multi-grade classification, but contain some sort of additive that acts like a VII. That new additive is quite likely sacrificed, sheared or lost in translation over the duty cycle of the lubricant.
They do NOT have to contain another additive.
Let's take Amsoil ACD for example:
http://www.amsoil.com/shop/by-product/mo.../?code=ACD1G-EA
It is a 30W/10W30 because of the base oil viscosity mix.
I am not saying these are Amsoil's formulation(s) but merely using these ratios below to prove a point.
A base oil is NOT one Single viscosity of base oil as I have explained many times here.
A formulator can take a binary blend (a blend of two base viscosities), or a ternary (a blend of three base viscosities), or an n-ary (a blend of "n" viscosities where n is any number) to make a base mix oil behave any way he desires.
------------------------------
For example a 5W30
PAO 4 14%
PAO 20 56%
------------------------------
A 5W40
PAO 4 20%
PAO 6 48%
PAO 65 2%
-----------------------------
A 10W30/30
PAO 6 25%
PAO 8 44%
PAO 150 1%
----------------------------
Here's the main point:
By introducing a low percentage of high viscosity base oil (which would have a high Viscosity Index and a relatively high HTHS), one can make a mono-grade oil that also behaves as a multi-grade oil.
My guess is that those high VI lubricants that do not need VII to achieve a multi-grade classification, but contain some sort of additive that acts like a VII. That new additive is quite likely sacrificed, sheared or lost in translation over the duty cycle of the lubricant.
They do NOT have to contain another additive.
Let's take Amsoil ACD for example:
http://www.amsoil.com/shop/by-product/mo.../?code=ACD1G-EA
It is a 30W/10W30 because of the base oil viscosity mix.
I am not saying these are Amsoil's formulation(s) but merely using these ratios below to prove a point.
A base oil is NOT one Single viscosity of base oil as I have explained many times here.
A formulator can take a binary blend (a blend of two base viscosities), or a ternary (a blend of three base viscosities), or an n-ary (a blend of "n" viscosities where n is any number) to make a base mix oil behave any way he desires.
------------------------------
For example a 5W30
PAO 4 14%
PAO 20 56%
------------------------------
A 5W40
PAO 4 20%
PAO 6 48%
PAO 65 2%
-----------------------------
A 10W30/30
PAO 6 25%
PAO 8 44%
PAO 150 1%
----------------------------
Here's the main point:
By introducing a low percentage of high viscosity base oil (which would have a high Viscosity Index and a relatively high HTHS), one can make a mono-grade oil that also behaves as a multi-grade oil.
Last edited:
MolaKule
Staff member
Correction: This example should have been:
------------------------------
For example a 5W30
PAO 4 56%
PAO 20 14%
------------------------------
------------------------------
For example a 5W30
PAO 4 56%
PAO 20 14%
------------------------------
Thanks Molakule, for the recipes.
I'd clarify that instead of "behaves like a multigrade" should be "meets the performance requirements of a multigrade"
I call the distinction, as what you've described is a Newtonian Fluid, not having a temporary shear loss at high shear rates as is the behaviour of a typical multigrade.
I'd clarify that instead of "behaves like a multigrade" should be "meets the performance requirements of a multigrade"
I call the distinction, as what you've described is a Newtonian Fluid, not having a temporary shear loss at high shear rates as is the behaviour of a typical multigrade.
I've read "bright stock free" as part of a lubricant's description.
Is the addition of a small percentage of a high viscosity base oil to tweak the viscosity of the finished product higher the description of a bright stock containing lubricant?
If correct, in the above examples, PAO served as the bright stock.
I would imagine that additive packages can be formulated to simplify the blending process depending on the size of the batch and length of the run.
Lubricant companies large and small would have to work closely with base oil supply, whether in house or not, and additive companies to arrive at the desired finished product.
After all that trouble, testing and certifying some find it necessary to add a can of this or that to the formula at every oil change.
Do we primates still have an inherent penchant for magic?
Is the addition of a small percentage of a high viscosity base oil to tweak the viscosity of the finished product higher the description of a bright stock containing lubricant?
If correct, in the above examples, PAO served as the bright stock.
I would imagine that additive packages can be formulated to simplify the blending process depending on the size of the batch and length of the run.
Lubricant companies large and small would have to work closely with base oil supply, whether in house or not, and additive companies to arrive at the desired finished product.
After all that trouble, testing and certifying some find it necessary to add a can of this or that to the formula at every oil change.
Do we primates still have an inherent penchant for magic?
The thread topic started by URS4 in the HD Diesel section
"What will happen if?" Got me searching where I posted
my UOA results from a PCMO in a Duramax engine.
My fuel economy findings were far from scientific, but not yet duplicated.
I've tried SAE 40 (bad) and now SAE 30 which is slightly better than the base-line 15w40.
I am holding out for the new 15W30 class results in the field.
The other application of this thread topic is it's relevance to ISO 22, 32 and 46 hydraulic/turbine fluids.
Sometimes we get so wrapped up in our own little world (engines), that we miss the
bigger picture which explains things better.
For the longest time I believed that group 2 lubricants had better shear resistance and load carrying capacity than group 3s and PAOs.
I must of read that somewhere and "learned it first" for it to stick.
Then I connected the dots all over the bobistheoilguy map, and it stopped making sense.
Where I'm going with this, I'm not exactly sure.
Farmer Brown has left the building.
"What will happen if?" Got me searching where I posted
my UOA results from a PCMO in a Duramax engine.
My fuel economy findings were far from scientific, but not yet duplicated.
I've tried SAE 40 (bad) and now SAE 30 which is slightly better than the base-line 15w40.
I am holding out for the new 15W30 class results in the field.
The other application of this thread topic is it's relevance to ISO 22, 32 and 46 hydraulic/turbine fluids.
Sometimes we get so wrapped up in our own little world (engines), that we miss the
bigger picture which explains things better.
For the longest time I believed that group 2 lubricants had better shear resistance and load carrying capacity than group 3s and PAOs.
I must of read that somewhere and "learned it first" for it to stick.
Then I connected the dots all over the bobistheoilguy map, and it stopped making sense.
Where I'm going with this, I'm not exactly sure.
Farmer Brown has left the building.
- Status
Similar threads
- Locked
