Shifting Stribeck Curve to the Left: What to Use?

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Originally Posted By: turtlevette
Originally Posted By: Shannow
[If you've mistaken MOFT for "film strength",


I don't get the distinction. But I do get you're attempting to back out of a poor position. It's all documented. I stand by my paraphrasing of your position.


Bull....

Here's the thread discussing MOFT, and your assinine suggestion that a "magic molecule" 20 could have a greater MOFT than a 40...MOFT is clearly viscosity dependent.

in the BMW thread
 
Originally Posted By: Shannow
Originally Posted By: turtlevette
Originally Posted By: Shannow
[If you've mistaken MOFT for "film strength",


I don't get the distinction. But I do get you're attempting to back out of a poor position. It's all documented. I stand by my paraphrasing of your position.


Bull....

Here's the thread discussing MOFT, and your assinine suggestion that a "magic molecule" 20 could have a greater MOFT than a 40...MOFT is clearly viscosity dependent.

in the BMW thread


So you don't believe in super-lubricity (SL). You don't believe that long chain molecules provide higher effective viscosity than organic molecules?

Let's pin down your position before I lower the boom on you.
 
Originally Posted By: turtlevette
Originally Posted By: Shannow
Originally Posted By: turtlevette
Originally Posted By: Shannow
[If you've mistaken MOFT for "film strength",


I don't get the distinction. But I do get you're attempting to back out of a poor position. It's all documented. I stand by my paraphrasing of your position.


Bull....

Here's the thread discussing MOFT, and your assinine suggestion that a "magic molecule" 20 could have a greater MOFT than a 40...MOFT is clearly viscosity dependent.

in the BMW thread


So you don't believe in super-lubricity (SL). You don't believe that long chain molecules provide higher effective viscosity than organic molecules?

Let's pin down your position before I lower the boom on you.


boom away...

You misrepresented out discussion in the BMW thread about bearing MOFT to a boundary layer discussion, now are asking me another question entirely.

turtlevette, you are beating me down with experience in your realm.
 
I've got to go with turtlevette (mostly) on this one. But Shannow is not really wrong either in my opinion. ......... Here's what happens: As the oil film gets thinner and thinner from normal viscosity & speed effects, it gets down to a thin layer of tenacious, tough, slimy, polar, stick-to-metal molecules that make a tough tribofilm. There is also lots of evidence this tribofilm also maintains a layer of oil on top of it in an elastic, compressed manner. (See Croda's "Ester Lubricity Agents" illustration I posted above and watch it happen.)
 
One question I have is: Does Castrol Magnatec have polymer esters that do this, giving them their marketing campaign? Or is it something else?

Also, does moly maintain a tougher oil film on top of it as well as the polymer ester chemistry appears to? Or is moly more a case of plating flat crystals to fill asperities in the metal?
 
Originally Posted By: aa1986
Ionic liquids appear to alter the Stribeck curve - although it's not a shift to the left.

Now are IL's considered additives or base oil substitutes? From what I've read, you only need a small proportion of IL to improve the friction and wear characteristics of PAO so in that respect it seems to be an additive?


IL's do shift the Stribeck curve to the left. It is an additive. From tech papers and discussions here, I've concluded that IL's are too surface-competitive (interfere with anti-wear stuff already in normal motor oil), so that make poor aftermarket oil additives. In the class of stuff you can add to oil that doesn't interfere with whats already in motor oil, polymer esters have the lead, maybe moly, and I don't know what else. OK, chlorinated parrafins not bad either I guess. Any more though?
 
Originally Posted By: aa1986
You sure it shifts to the left? I saw something different.


Its got to. Its that rapid rise of friction which indicates when asperities (peaks) in the metal surface are being grazed. IL creates a tougher thin oil film, delaying when that rapid rise in friction occurs, so thats moving it to the left (compared, of course, to white oil, or even oil with just ZDDP in it).
 
For example see, this graph about IL from the CRADA research that Shell and ORNL did:
IL_zpssa58rtig.jpg
 
My bad, I thought I read somewhere that you can't just throw in IL as an extra additive on top of normal current motor oil and get synergism. Now I see statements that IL is synergistic with ZDDP.

"When added into 5W30 engine oil, [P66614][DEHP] further reduces wear – suggesting a
synergistic anti-wear effect with ZDDP."
from the page 13 of http://energy.gov/sites/prod/files/2014/03/f8/deer12_qu.pdf

Yet, no IL additive bottle on store shelves, only polymer esters, moly and moly-boron, and chlorinated parrafins from what I've seen are the choices now.
 
Last edited:
What's the difference in what is being plotted on the x-axis for the chart you posted vs that graph on slide 6 of the link I gave?
 
Originally Posted By: CrawfishTails
Yet, no IL additive bottle on store shelves, only polymer esters, moly and moly-boron, and chlorinated parrafins from what I've seen are the choices now.


There appears to be some sort of patent on the IL. Perhaps a snake oil company can't get their hands on it or haven't discovered it yet.

Plus it seems to be expensive, and it's benefit is enabling fuel economy by allowing the use of lower viscosity oils than specified. So what's the sales pitch for the masses?

So it hardly seems to be the right ingredient for snake oil when you could simply dye kerosene red instead.

Nope, this additives is going to need to developed as part of a low viscosity (0w12 / 0w16) fully formulated oil specification in concert with new engine development and / or engine back spec testing.
 
Originally Posted By: aa1986
Nope, this additives is going to need to developed as part of a low viscosity (0w12 / 0w16) fully formulated oil specification in concert with new engine development and / or engine back spec testing.


Yep, I think thats the same conclusion I reached before. Still, they might find a way to just put a smidgen in any oil and expect an anti-wear and/or friction benefit. Hopeful. Not there now. As for the patents, since ORNL, a federal lab, got involved, it should be easier to buy the rights to use it.
 
Originally Posted By: aa1986
What's the difference in what is being plotted on the x-axis for the chart you posted vs that graph on slide 6 of the link I gave?


I'll post the two graphs in question (I'm a tad confused here):
IL_zpssa58rtig.jpg

confusingGraph_zpszkseydfx.jpg
 
Seems to me the 2nd graph I posted above is not right. I mean, viscosity is already a part of the Stribeck curve, so using a different visc oil doesn't SHIFT the curve, right??!!

The 1st graph I posted above makes sense to me, although it too contains that confusing double-line difference between a plain high-visc and low-visc oil. The main gist is that IL, like polymer esters, makes a thin oil film tougher to penetrate, shifting the Stribeck.
 
I see what they are doing now: They took viscosity OUT of the x-axis. Thats not what I'm used to seeing in Stribeck curves, as its usually visc x speed / load. They are doing just speed/load, or maybe that sigma greek symbol is the reciprocal of viscosity(???).
 
Actually, I think I understand it now. The green line is a low viscosity oil with no IL additive.

Take any point of the x axis where the green line is below the high viscosity oil and it is showing that a low viscosity oil has less friction in hydrodynamic lubrication.

However, once in mixed lubrication, a higher viscosity oil has lower friction.

What they are suggesting is that adding IL will retain the advantages of low viscosity oil ie where the green line is below the brown line, and then offset the worse performance that a low viscosity oil has in mixed lubrication.

It would then be like the chart you posted.

And if this stuff becomes available, it will be interesting to watch the discussions that take place when people refuse to believe that a 0w12 with IL is better than an old school 0w20 or 0w30.
 
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