Molybdemum and water

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Little Rock, AR
So I'm do some leisurely reading in a tribology book on the web yesterday - it states that Molybdenum breaks down fairly easily when reacting with water. The byproducts are not corrosive - but it does decompose. Meanwhile, Schaeffers relies heavily on Moly for AW and AF, and Sch. is known for good UOAs at reasonably extended OCIs. Is there concern in using it in a long drain app that could be considered severe (high humidity, lots of engine starts thru the day, perhaps monthly full burn-offs) ?
 
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Moisture is detrimental to oil in general, not just moly. If you're going to have oil subject to such conditions, not allowing it to burn off all the fuel and water condensation at least once a week, then I would change it more frequently, regardless what additive package it contains. What is your idea of "long drain" in terms of miles/time? I do a once a year OCI myself, but the car does get fully warmed up at least once a week. UOA hasn't shown any issues.
 

ericthepig

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Little Rock, AR
Quatro, intended OCI is 1 yr/12k miles. Yeah, I understand water is the needed ingrediant for just about every bad thing that can happen in the crankcase. The car in question rarely gets to op temp, but then it doesn't have much time to cool down during a typical day either (several of 2 to 8 round mile trips thru-out a typical day). Full good burn-off about once/mo. Sump is 4+ qts.
 
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Which kind of Moly breaks down with water? Is it the soluble Moly DTC type or the insoluble type? I assume that shaeffers, redline, M1 0W40, Rotella, etc, and others that use moly use soluble moly. It seems there is tons of info. out there that relates to insoluble moly (powders, etc.) that gets passed on as if it also applies to insoluble moly. I was just wondering if that might be the case here. Here is one example (not relating to water though):
 Originally Posted By: MolaKule
 Quote:
Bob Cousimano over at CMW Oil also is a firm believe that soluble moly products should not be used in automotive lubricants, just like PTFE (teflon) and many other oil additive products like Prolong, Slick 50, and countless others just plain don't work and should never be used in an engine.
Indeed, this is an old report, comes up occasionlly, and has been discussed at least three times before. To compare soluble moly to the snake oil additives is ludicrous. The fact is, a specific and early compound of moly, a class of molybdenum phosphordithioates, was "suspected" as being the cause of some corrosion. There was never a proven correlation. Interestingly, those same molybdenum phosphordithioates have been used successfully in hydraulic oils without any problems or suspected corrosion problems. Today's modern molybdenum dithiocarbamates, have never been the center of controversy or suspected corrosion. In addition, the comment about the copper deactivator is also out of date and no longer correct.
 
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Here is a great link that JAG posted previously that lists the specs for lots of Moly additives. It looks to me like it really depends on the specific additive. For example Molyvan A (Molybdenum di-n-butyldithiocarbamate) is insoluble in water and oil. Molyvan 807 (Molybdenum dialkyldithiocarbamate in oil) is insoluble in water but soluble in oil. Also in reading the descriptions, their reactions to metal etc. are quite different. This indicates to me that a home user adding an off the shelf moly additive to oil may be a real hit or miss proposition. It looks like there is a lot that goes into getting the right additive and balancing that with the other additives, base oils, etc. of the oil. In other words, in the hands of the tribologist "artist", Moly is a great color to have on the palette board. In the hands of a novice, it might just make a mess of the canvas. So based on this, it looks to me that generalizations about "moly" are pretty meaningless. For example the statement, "Moly is corrosive to soft metals". It really depends on the specific additive. But I don't know that much about it yet and maybe TomNJ, JAG, or Molakule can lay it out better. Here's the link: http://www.rtvanderbilt.com/petro_2_a.htm
 
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