Is Moly Overrated?

[Patman]

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Originally posted by buster:

quote:

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Redline uses 7-8 times as much moly as is used in Mobil 1, but I'd have to say that for shorter change intervals on the order of 5000-7500 miles, the M1 results have been more consistent

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Yep.

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I don't believe this to be true, we simply have a larger sampling of M1 reports. Plus a lot of the Redline reports are of their first interval, which show higher wear metals due to the aggressive cleaning action.

 

[TooSlick]

Drstressor,

Thanks for the very concise explanation ...it confirms what I suspected but did not understand the chemical basis for. In fairness to Redline, I think they are formulating for a particular type of end user. This is somebody who drives very hard but is not necessarily looking to run what I would consider to be extended drain intervals. I can see where the additional moly could be beneficial if you autocross or race occasionally.

TooSlick

 

[J]

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Originally posted by Ken2:
First, the moly used in engine oils is molybdenum trialkyldithocarbamate or a related compound, not MoS2. Second, many oil blenders do mix MoTDC and ZDDP in their additive packages.

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Hi,

Since you mention it, could you tell me
whether or not MoTDC and ZDDP react to produce
MoS2, which provides the real barrier protection?

I just want to know how your statements
can be reconciled with the following link :
moly basics.

I don't doubt that you guys know more about
this stuff than I do.

Jae

 

[Ken2]

Bob's link, while very informative, isn't clear that the moly in motor oil is not the solid MoS2.

Molybdenum trialklydithiocarbamate is completely soluble in oil, not suspended in a solid particle form.

When you see "...thio..." in a chemical name, you know that it contains sulfur atoms, in this case two per molecule of MoTDC. Under the heat formed by friction between two surfaces in boundry lubrication conditions the MoTDC plates MoS2 (created from the molydenum and sulfur in the MoTDC) on the metal surfaces. I've been told that the MoS2 never gets more than one-half ten-thousandths of an inch thick.

'kule, did I get that all right?


Ken

 

[MolaKule]

J,

The moly in molybdenum trialkyldithocarbamate (MoTYDC's) starts out as a moly "pentasulfide" salt with a dithiocarbamate acid added. The salts are then stabilized with poly phenylene sulfide polymers and an alkyl group of 2-ethylheyl's. The result is a polymerized fluid that is slightly golden in color (light amber).

When in oil, the MoTDC decomposes to form "moly sulfide films on frictional surfaces, of which the particles adhered to the porous iron sulfide film produced by the reaction of the decomposed sulfur compounds and iron surfaces, and that these components make an extreme pressure or anti-wear film."

When used with ZDDP, a third layer of film is formed which creates an iron phosphide film. Stating it another way, three films are formed to create a plastic layer; MoS2, FePO4, and FeS. It is these three films that react under pressure to form a plastic "sliding" layer which prevents metal contact. I.E., instead of metals gouging into each other, they slide over one another on this "plastic" film.

 

[J]

quote:

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Originally posted by MolaKule:
J,

The moly in molybdenum trialkyldithocarbamate (MoTYDC's) starts out as a moly "pentasulfide" salt with a dithiocarbamate acid added. The salts are then stabilized with poly phenylene sulfide polymers and an alkyl group of 2-ethylheyl's. The result is a polymerized fluid that is slightly golden in color (light amber).

When in oil, the MoTDC decomposes to form "moly sulfide films on frictional surfaces, of which the particles adhered to the porous iron sulfide film produced by the reaction of the decomposed sulfur compounds and iron surfaces, and that these components make an extreme pressure or anti-wear film."

When used with ZDDP, a third layer of film is formed which creates an iron phosphide film. Stating it another way, three films are formed to create a plastic layer; MoS2, FePO4, and FeS. It is these three films that react under pressure to form a plastic "sliding" layer which prevents metal contact. I.E., instead of metals gouging into each other, they slide over one another on this "plastic" film.

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Hi MolaKule,

Thanks for the explanation. The valedictorian
in my college class was a chemical engineer.
Chemical engineers sure earn their keep,
I can tell you that right now.

By the way, I looked at the Lasche McKee
equations. They seem straightforward enough, but
I do not have a repair manual of my own. I
was thinking that I would just ask techs on
another BB but decided against it. Trying to
get them to give me the right numbers to plug
into the equations would have caused me much
more aggravation than just buying a repair
manual for myself.

Right now, I have put myself on self-imposed
spending freeze (what with the oil analyses and
building of my oil shrine which will last a
full decade almost completely unused). So, it
will take me some time before I can tell you
what I discover regarding Saab oil recommendation
as it relates to CAFE.

Jae

 

[MolaKule]

Thanks.

I also have a Matlab source code listing if anyone wants it; it works well and I checked its accuracy with my calculator.

One could make minor changes and put it into fortran or MathCad or whatever if they choose.

 

[MolaKule]

I'll post under the Interesting Articles thread.

 

[J]

quote:

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Originally posted by MolaKule:
Thanks.

I also have a Matlab source code listing if anyone wants it; it works well and I checked its accuracy with my calculator.

One could make minor changes and put it into fortran or MathCad or whatever if they choose.

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Hi,

Could you post it or send it to me? I have
Matlab here at work. I can also convert it to C
code. One job I had at a now defunct start-up
was transcribing Matlab code to C code.

thanks

Jae