Molybdenum and Engine Deposits

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Since I have started trying to learn about motor oils, I have been reading that "moly causes engine deposits".
The abstract of this paper alludes to this, saying that MoDTC "is also widely known to cause deposit accretion in the Thermo-Oxidation Engine Oil Simulation Test (TEOST 33C)."
http://papers.sae.org/2008-01-2480/
However, I usually see the TEOST "problem" referred to when MoS2 is brought up, and I know that it's likely the compound and not one particular element in it we need to consider.
To make things really confusing, here is a paper that claims that MoDTC can result in reduced deposit levels in the presence of other oil additives...
http://www.savantgroup.com/media/2005-Pa...e-Oils-STLE.pdf
. And, a paper in this book also claims that "molybdenum ion" in oil can reduce deposits and make oil less likely to oxidize when used properly with other additives, but I don't know how ionized molybdenum is introduced to oil. Some key pages here are not visible, sorry.
https://books.google.com/books?id=y7VoYR...ost&f=false

There is probably not a single, easy answer here, but my basic question is whether the presence of MoS2 in oil can lead to increased deposits, and I would also like to understand more about the functions and risks of molybdenum compounds in oil in general.
Help!

EDIT - just want to make it clear that I understand that MoS2 is a solid that works by adhering to metal surfaces experiencing friction...that is not the "deposit" I am thinking of. I am asking about carbon deposits, of course.
 
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Solid that falls out of suspension is a deposit. By adhering it reduces wear materials that are deposits. Reducing friction also reduces heat causing deposits to form. That's my basic understanding of moly and I refuse to get involved in that religion. :)
 
Well......grab the popcorn.....this is going to ignite a firestorm.

I have lurked here for years...read literally tens of thousands of posts......

....and all of the stuff I have read, really, really boils down to this: Use a top quality oil like Mobil 1 Extended Protection, Penz Ultra Plat, or some other absolutely top of the line synthetic oil..........use a top of the line synthetic fiber filter..........change the oil every 3-5 thousand miles and your engine will pretty much last a lot longer than the chassis of your vehicle (gas powered regular car/truck).........

the engine will literally last a lot longer than you need it to or want it to................

that is all........
 
No ... that's run any oil and any filter and change it a couple times a year
smile.gif




( ... Not MY conclusion)
 
The TEOST tests, all of them, are nuts! They are completely meaningless. They correlate with nothing. Savant should be ashamed of themselves for inflicting this nonsense on the industry.
It's hard to give a 100% cover-all answer to every situation but Moly compounds, the oil soluble variety that get used in most commercial oils, tend to reduce deposits, primarily because they can be very effective antioxidants.
 
Originally Posted By: SonofJoe
The TEOST tests, all of them, are nuts! They are completely meaningless. They correlate with nothing. Savant should be ashamed of themselves for inflicting this nonsense on the industry.
It's hard to give a 100% cover-all answer to every situation but Moly compounds, the oil soluble variety that get used in most commercial oils, tend to reduce deposits, primarily because they can be very effective antioxidants.


This is very much in line with the second paper I mentioned above.
I kept using some MoS2 at my changes even after getting scared about "deposits" because some studies showed that moly could reduce LSPI frequency in DIT engines...but, of course, that was the soluble MoDTC and not MoS2. I think M1 has sufficient MoDTC for that, anyway.
I still have a partial can of LM MoS2 in the garage and am trying to figure out whether I should use it up or just give it away. But, most of all, I am curious...
 
Great post Virtus_Probi. There just isnt an easy answer. For every choice made, sacrifices are made elsewhere.
 
I've used for several years and inumerous Ocis, including an engine that I tore down. Several filters cut open. Never seen moly deposits or fall offs, just a littlenormal hard brownish crud in a few filters. Maybe in the ring pack of severely stressed engines, but I never saw on mine.
 
Originally Posted By: Virtus_Probi
Since I have started trying to learn about motor oils, I have been reading that "moly causes engine deposits".
The abstract of this paper alludes to this, saying that MoDTC "is also widely known to cause deposit accretion in the Thermo-Oxidation Engine Oil Simulation Test (TEOST 33C)."
http://papers.sae.org/2008-01-2480/


This paper has to do with decomposition of MoDTC and ZDTP (ZDDP) as well as a comparison to other sources of Molybdenum and their TEOST deposits which are formed at VERY high temperatures (480C). The TEOST deposits they found contained Molybdenum and that is hardly surprising at that temperature.

Quote:

However, I usually see the TEOST "problem" referred to when MoS2 is brought up, and I know that it's likely the compound and not one particular element in it we need to consider.
To make things really confusing, here is a paper that claims that MoDTC can result in reduced deposit levels in the presence of other oil additives...
http://www.savantgroup.com/media/2005-Pa...e-Oils-STLE.pdf

This on the otherhand talks about the antioxidant ability of molybdenum compounds - this is because most additives in a engine oil package are multifunctional and are designed with certain synergies in mind. This is why most formulators will discourage the addition of extra OTC additives because it may disrupt the balance of oxidation resistance, corrosion protection, surface activity, synergy between ZDDP and MoDTC, etc etc.

THEY AREN'T LOOKING AT THE SAME THING.


Here is what we know about Molybdenum compounds:
1- They function very well as friction modifiers at low temperatures
2- They complement ZDDP well at the right ratios to produce Fuel economy benefits in the Sequence VI test
3- MoDTC has some anti-oxidant properties. As such will reduce deposit precursors at typical engine oil temperatures.
4- Molybdenum compounds pull in Sulfur from ZDDP to form MoS2 on top of ZDDP glass in the tribolayer. This is a chemical reaction that occurs which is synergistic with ZDDP.
5- The reaction discussed in 4 has a saturation limit in that adding more of either ZDDP or Molybdenum compounds doesn't provide any additional benefit - this is especially true as the oil ages.
6- They are commonly used in PCEO, especially those that are looking to maximize fuel economy gains in the Sequence VI test.
7- At extremely high temperatures (such as in Turbo's) you may find some stray Molybdenum in the deposits that form. Balancing this with the fuel economy is the reason it costs so much money to develop new engine oil formulations.
 
Thanks to Solarent for his detailed and very helpful post.

Originally Posted By: Solarent

7- At extremely high temperatures (such as in Turbo's) you may find some stray Molybdenum in the deposits that form. Balancing this with the fuel economy is the reason it costs so much money to develop new engine oil formulations.


This tips me away from putting any more in my FXT...I'll see if anybody at work is interested in half a bottle of LM MoS2 and probably use it up in one of our NA cars if I don't find a taker. I think I've finally gotten away from messing around with oil additives and will trust in the top notch oil that I buy.
 
Can I ask, which graphited oil did you use? how do you know the origin of the dirt? Can't it be from the last oil fill?
 
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I just put powdered graphite (I know it is believed to be dangerous for impurities, but never lost an engine for that) in the fill of a usual semisyn 10w40 oil. The engine got cleaner from what I saw from the the valve covers gasket jobs AND THE TEARDOWN LATER to solve a centenary piston slap on cyl #1. Engine EJ16, scooby. I do my own engine jobs.
 
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Originally Posted By: Solarent


...This on the otherhand talks about the antioxidant ability of molybdenum compounds - this is because most additives in a engine oil package are multifunctional and are designed with certain synergies in mind. This is why most formulators will discourage the addition of extra OTC additives because it may disrupt the balance of oxidation resistance, corrosion protection, surface activity, synergy between ZDDP and MoDTC, etc etc...




I certainly wish we could convince the OTC additive junkies of this situation.
 
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I just put powdered graphite...


I don't see any technical basis for adding more carbon molecules to an oil.
 
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diamonds are pure carbon, graphite is pure carbon, soot isn't pure carbon but has a lot of it.

3 very different products with very different properties
 
Originally Posted By: MolaKule
Originally Posted By: Solarent


...This on the otherhand talks about the antioxidant ability of molybdenum compounds - this is because most additives in a engine oil package are multifunctional and are designed with certain synergies in mind. This is why most formulators will discourage the addition of extra OTC additives because it may disrupt the balance of oxidation resistance, corrosion protection, surface activity, synergy between ZDDP and MoDTC, etc etc...




I certainly wish we could convince the OTC additive junkies of this situation.


I think I am finally seeing the light!
(cue the gospel choir)
 
Originally Posted By: stephenbrown22
Well......grab the popcorn.....this is going to ignite a firestorm.

I have lurked here for years...read literally tens of thousands of posts......

....and all of the stuff I have read, really, really boils down to this: Use a top quality oil like Mobil 1 Extended Protection, Penz Ultra Plat, or some other absolutely top of the line synthetic oil..........use a top of the line synthetic fiber filter..........change the oil every 3-5 thousand miles and your engine will pretty much last a lot longer than the chassis of your vehicle (gas powered regular car/truck).........

the engine will literally last a lot longer than you need it to or want it to................

that is all........
I have been around long enough to say with authority that any oil that meets the specs and 3 to 5,000 mile oil change intervals and any filter that doesn't fail will lead to a longer than necessary engine life with out falling for the marketing and hype of those that think they know. Unless you live where the tarting temps get below 0*f then syn is nice.
 
Originally Posted By: MolaKule
Quote:
I just put powdered graphite...


I don't see any technical basis for adding more carbon molecules to an oil.


Carbon attracts carbon, if not, sludge crude wouldn't build up and accumulate in engines. Neither dispersant would be necessary. Just arguing.

Maybe you don't see basis, but why Atlantic Richmond (Arcographite), Elf (Molygraphite), Krex, and others saw then, why?
Just curious.
 
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