MoS2 insoluble moly vs PCMO moly compatible?

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Okay, background then questions.

I'm a big fan of Pennzoil in my Jeep and will be running that for the foreseeable future. PYB is very high in moly as most here know.

Due to concerns with the piston skirts on my Jeep engine (a known weakness in the model) I have also been using MoS2 off and on in the past, now on again and I plan to stick with it as well. It is my hope the MoS2 may offer a little more protection for the piston skirts. Not sure it will help but I don't see any way it could hurt, and I put so few miles on the Jeep anymore the expense is negligible.

Here's the question though, does anyone know if the MoS2 might actually interfere with the soluble moly in the PYB, inhibiting it from doing it's job? Are these two moly's "competing" with each other?

My understanding is the MoS2 plates under heat, and once plated wants to stay there, which is why I thought it couldn't hurt with the skirts. Once plated I also thought it would be good for short trip protection (which I do a lot of these days). But I also wonder if it prevents the PYB moly from performing as it should.

I plan to stick with the PYB and MoS2 but this has got me thinking and wondering if I should rethink my strategy. Would the MoS2 be better off with a PCMO that has no moly? Would the PYB be better off with no MoS2? Some of the recent UOA's with PYB in the Jeep 4.0 have been amazing. I did one UOA a few years ago with Castrol HM and MoS2 that was not very impressive but there were other things going on OCI also I think.

Thoughts????
 
The piston skirt issue is a mechanical failure. Nothing you put in the oil or any brand of oil you use can prevent it or even reduce the chance of a defective skirt coming apart.

I wouldn't mix moly of different chemistries together, who knows what happens to the additive balance of the oil.
IMHO you want a better oil, buy it but don't waste your money attempting to fortify a lesser oil.
 
Sure it competes, but that is not necessarily bad. The film that is produced by the soluble moly is essentially MoS2. I'm not convinced that MoS2 as an additive provides any additional benefit and under certain circumstance may actually become detrimental, but the protective coating that is produced by either is very similar. In a way, any surface that is plated by MoS2 from your additive is also a surface that does not need the soluble moly at that particular moment. Since they do the same thing (for the purposes of this discussion), competition is not an issue. On the other hand, competition between compounds that have different roles in oil may be an issue -- a moly compound and a detergent for example.
 
GMorg,
that's the argument that has me flip flopping on this particular additive. The soluble molys make it and as the oil is aged, you get a broader spread of moly compounds from what was originally thrown into the lube.

While not an additive fan, this is almost like "pre-conditioning" the oil...but a bottle does me 13 litre of oil by the time half goes in the Nissan, the other half in the Holden, and the remainder in the yard equipment.
 
My biggest worry with MoS2 is agglomeration between the moly and colloidal additives, metal debris, and partial combustion products (soot) -- especially if there are VIIs in the mix. In addition, I don't think that we can always predict the interaction between the non-disclosed dispersants in the moly and the multitude of non-disclosed additives in the oil.

I have a feeling that that we would see more MoS2 in fully formulated oil if it didn't have to have such a long shelf life.

Since my work allows me to routinely observe particles in the 0.5-100 micron range, often in the present of a dissolved polymer, I am absolutely convinced that the sort of flow that occurs in an engine would NOT guarantee that settled particles would be redistributed. Bulk flow does not act on tiny particles at/on surfaces.
 
Originally Posted By: Trav
The piston skirt issue is a mechanical failure. Nothing you put in the oil or any brand of oil you use can prevent it or even reduce the chance of a defective skirt coming apart.



+1 MOS2 is snake oil. Save your money.
 
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Originally Posted By: GMorg
Sure it competes, but that is not necessarily bad. The film that is produced by the soluble moly is essentially MoS2. I'm not convinced that MoS2 as an additive provides any additional benefit and under certain circumstance may actually become detrimental, but the protective coating that is produced by either is very similar. In a way, any surface that is plated by MoS2 from your additive is also a surface that does not need the soluble moly at that particular moment. Since they do the same thing (for the purposes of this discussion), competition is not an issue. On the other hand, competition between compounds that have different roles in oil may be an issue -- a moly compound and a detergent for example.


Very interesting. Is this perhaps the reason PYB, which is higher in soluble moly than any conventional I know of (around 250 ppm) also happens to have a higher detergent level than any conventional I know of? PYB averages 2,400-2,500 ppm Calcium per analysis almost everything else is around 2,100 ppm.
 
I cannot know the answer to your question, but your suggestion is a fine guess.

I do think that surface competition with esters is the driver behind why RedLine has such high moly.
 
kcjeep,

Have you given any more thought to this? I will be near an oil change in a week or two as I approach 7500 miles on my current fill of PenzHM 5w-20 with MOS and MOS2 and a fram ultra.(i have a thread on this)

I thought I could run a fill of non detergent oil with the MOS2 and see what i experience.
 
If you use MoS2 in a non-detergent oil, you are going to be completely dependent on the dispersants in the MoS2 can. I think that you have more trust in your MoS2 supplier than I would have.
 
I hear that...

The other issue is most non detergent oils are straight weights except maybe for a 20w50.(that i can find on line, but likely hard to find locally and i would not want to run that in the winter if at all) other's please post if you have some info on multi viscosity non detergent oils.

Looking for a low calcium oil on pqia, i find castrol edge 0w20 with a 685 calcium, the lowest of the sample's on their website. However the mag(disp) goes considerably higher up at 1530. other data for this oil: phosp 753, Zn 834 and Moly 81.

It is full synthetic 0w20...

Any other thoughts on low detergent oils to run? thanks
 
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Since I can't get my mind around a motivation to run a low detergent oil, and additionally to run a low detergent oil with a circulating solid, I can't even begin to make suggestions.

I can't figure out what you are trying to do, nor why you trying to do it.
 
Thank you, I was beginning to think I was the only one who wasn't getting it.

It's like saying you want to run plain water in your cooling system and wondering what additives would be best to make that happen (but you've ruled out using the proper coolant).

Originally Posted By: GMorg
Since I can't get my mind around a motivation to run a low detergent oil, and additionally to run a low detergent oil with a circulating solid, I can't even begin to make suggestions.

I can't figure out what you are trying to do, nor why you trying to do it.
 
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