MoDTC effect on wear rates

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JAG

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http://www.sae.org/technical/papers/2004-01-2005

"Abstract:
The effects of lubricating oil on friction and wear were investigated using light-duty 2.2L compression ignition direct injection (CIDI) engine components for bench testing. A matrix of test oils varying in viscosity, friction modifier level and chemistry, and base stock chemistry (mineral and synthetic) was investigated.

Among all engine oils used for bench tests, the engine oil containing MoDTC friction modifier showed the lowest friction compared with the engine oils with organic friction modifier or the other engine oils without any friction modifier. Mineral-based engine oils of the same viscosity grade and oil formulation had slightly lower friction than synthetic-based engine oils.

In the comparison of wear on cylinder bores lubricated with the same viscosity of lubricant, the lubricant containing the MoDTC friction modifier had the lowest wear depth, probably because of a wear-resistant reaction film formed by the reaction of sulfur from ZnDTP (Zinc Dialkyl Dithiophosphate) and MoDTC. The wear depth of the engine oil without any friction modifier was the highest among all lubricants tested. With MoDTC in the engine oil, the wear depths for all tested piston rings were lower than those operating in the absence of MoDTC. This might be caused by a synergistic wear-resistant film formation (both MoS\d2 and polyphosphates formed) on both cast iron bores and piston rings as evidenced by EDX and XPS surface analyses. Surface analyses were conducted to help understand the surface mechanisms responsible for friction reduction and the impact of engine materials and additives on wear."
 
Interestng. Thanks JAG. I know some formulators still feel MoTDC + ZDP are still the best AW additives available.
 
Yeah those two additives together can make some really good anti-wear films according to numerous studies/tests that analyzed them along with other additive combinations.

The combination provides both low friction and low wear which don't always come together with some other anti-wear films resulting from different anti-wear additive combinations.
 
Originally Posted By: Linctex
Originally Posted By: JAG
http://www.sae.org/technical/papers/2004-01-2005

"Abstract:

Mineral-based engine oils of the same viscosity grade and oil formulation had slightly lower friction than synthetic-based engine oils."


Am I the only one to find this little tidbit to be rather amazing?


No, there's more "stuff" including polar molecules and sulfur bearing molecules...has a "little" anti wear effect in and of itself
 
Originally Posted By: Linctex
Originally Posted By: JAG
http://www.sae.org/technical/papers/2004-01-2005

"Abstract:

Mineral-based engine oils of the same viscosity grade and oil formulation had slightly lower friction than synthetic-based engine oils."

Am I the only one to find this little tidbit to be rather amazing?

Blast from the past! It is interesting. We don’t have enough details about the oils used, oil temperature, or where on the Stribeck curve they were operating in to give a definitive explanation of that. The HTHS viscosities, the type of synthetic oil (Group III or PAO or ester or some combination?) would be helpful. If an oiled component is operating on the left of the minimum friction location on the Stribeck curve, increasing the viscosity will decrease friction. Valvetrain typically is in that situation. If to the right of minimum, increasing viscosity increases friction. Maybe the HTHS viscosity of the synthetic differed from the mineral oils. Maybe the oil temperature was somewhat low, making the mineral oil viscosity higher than the synthetic. If left-of-minimum in Stribeck curve, that would cause lower friction.
 
But given that it's exploring the effect of friction modifiers (MoDTC), they are IN the zone where they work, not to the right on the curve.

Relationship+of+Stribeck+Curve+vs+Friction+Modification.png
 
Very good point, Shannow. I didn’t think of that. So then, higher viscosity, lower friction. There is also the matter of the pressure-viscosity coefficients being different for different base oils. Not sure if the pressures in the test were high enough to make that significant. I doubt it was in a test simulating a piston in a cylinder liner.
 
Not sure about rings, and the sliding type of motion WRT pressure/viscosity change.

Personally I don't THINK it would be much impact...I KNOW it's not a factor in bearings, the surfaces aren't strong enough...cams it's there for a bit, not sure on rings.
 
Originally Posted By: SR5
It sounds like ZDDP and MoDTC work well together.

I believe ZDDP is temperature-dependent and it's temperature-activated,
however MoDTC in non-temperature-dependent and it's pressure-activated or contact-activated.
 
Good thread and its over my head or my lack of interest but caught my attention for one reason.
Never mind the math, theories, should haves, could haves ...

To the layman, I always ask the same question and make the same statement.
I pretty much use the API conventional oils for my vechicles, always change at or most cases before the required OCI. More or less I stick to what would be the "Severe Use" OCI.
I do in my heart know synthetic is more stable and I do know, for someone who neglects OCIs they most likely would be better off with a synthetic, maybe.

But all these UOAs, since I change my oil ontime and before, have never shown me less wear in an apples to applies comparison of synthetic and conventional oil, in my heart, its marketing for greater profit.
Meaning they will formulate the oil however way they can to meet and exceed the API rating of the oil and I suspect even most conventional have a form of a syn blend now but will not be advertised as the company rather sell a more profitable oil labeled as such...

Have no idea why I am posting this *L* ... just seemed like the right thread. :eek:)
Knock on wood, but in decades of owning cars, trucks, boats and motorcycles, I never had an engine failure nor have I ever sold one off that was burning oil or engine defect in any way.
 
Last edited:
Originally Posted By: alarmguy
Good thread and its over my head or my lack of interest but caught my attention for one reason.
Never mind the math, theories, should haves, could haves ...

To the layman, I always ask the same question and make the same statement.
I pretty much use the API conventional oils for my vechicles, always change at or most cases before the required OCI. More or less I stick to what would be the "Severe Use" OCI.
I do in my heart know synthetic is more stable and I do know, for someone who neglects OCIs they most likely would be better off with a synthetic, maybe.

But all these UOAs, since I change my oil ontime and before, have never shown me less wear in an apples to applies comparison of synthetic and conventional oil, in my heart, its marketing for greater profit.
Meaning they will formulate the oil however way they can to meet and exceed the API rating of the oil and I suspect even most conventional have a form of a syn blend now but will not be advertised as the company rather sell a more profitable oil labeled as such...

Have no idea why I am posting this *L* ... just seemed like the right thread. :eek:)
Knock on wood, but in decades of owning cars, trucks, boats and motorcycles, I never had an engine failure nor have I ever sold one off that was burning oil or engine defect in any way.



Your comment is correct alarmguy, and it probably mimics the thinking of most owners. I also run what the manufacturer runs, use a good brand of oil and drive my vehicles in a sensible manner. I don’t like the idea of spending big money on something then abusing it by showing off. In that respect I also buy vehicles that meet not only my needs but also consider the type of driving and climate they will endure.
 
remember reading that due to the shearing of a lot of viscosity improvers added to mineral oil is temporarily shears in tests + reduces friction + real synthetic's group IV + V being shear resistant actually as noted has more friction, i think
 
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