Oil Additives

[Trav]

Some of you will remember my a build up in one of my engines that was pure MoS2.
I think i finally found an explanation.

This 3800 GenII is turbocharged and although run on synthetic oil it was mostly pre GF-5 with a HTHS of about 3.1. Later i started using HTHS 3.8 in it but most of the deposits were probably already formed.
Quote:
MoS2 has caused problems in some formulas. In rare instances the compound can come out of solution and form deposits. This is a particular problem in turbocharged applications...

The ILSAC GF-5 and/or Dexos approvals should remove the possibility of MoS2 deposit problems in low HTHS applications. Liqui-Moly has established an excellent reputation for using MoS2 in high HTHS applications without any deposit problems.


Not a knock of MoS2 just an reasonable explanation.

This article is worth bookmarking IMO. Its just info, feel free to rip the article to shreds if you don't agree, i didn't write it.

http://www.diagnosticnews.com/oil-additives-supplements/

 

[spasm3]

I did not see your build up. I have used lubromoly mos2. I know some piston manufactuers have coated coated their skirts in mos2. I do worry about deposits in the upper ringland areas where it gets hot. especially on newer engines where the top ring is really high on the piston.

 

[19jacobob93]

I'm using MoS2 and have been for over a year now. Worked in my engine to make it noticeably smoother and quieter and possibly slightly more efficient. It also turned oil consumption from almost nothing (0.3L in 10k) to completely nothing. I just used my last 2/3 bottle last week and for the next 2 or 3 OCIs (to give it chance to leave the system) I'm going to leave out the additives and see if I notice a difference.
If I notice anything negative I will continue using MoS2 the next change, If I notice nothing then I will probably stop using it

I'm also doing a UOA for the next drain with MoS2 and for the drain after without it using the same oil

 

[Trav]

I cant say if it did anything positive or not. It fell out of suspension and accumulated in the oil pan, the article seems to provide a reasonable explanation as to why that happened.
This thread is not intended to be a MoS2 pro and con thread.

High oil temp due to the turbo together with a lower HTHS of a pre GF-5 oil seems to be the cause.
I will say this put me off using any solids in the oil again, i gave my small stash of MoS2 and Ceratec away.

 

[JHZR2]

Well the settling time of MoS2 particles is dependent upon fluid viscosity and particle size. Id suppose that a higher HTHS viscosity would mean that in "dead zones" where there is no real mixing within the sump (if spots such as these exist), a higher HTHS would mean some sort of reduced particle settling.

To me its a stretch since the viscosity at 100C is the viscosity at 100C, but there may be something to it.

 

[Trav]

If that's the case then why bother with high HTHS? I don't know just a question.
This is what i don't understand..
Quote:
Liqui-Moly has established an excellent reputation for using MoS2 in high HTHS applications without any deposit problems.

 

[MolaKule]

Quote:
I know some piston manufactuers have coated coated their skirts in mos2.


True, but isn't this a solid moly that has been applied via plasma techniques and heat treated?

I don't think you can use this as an analogy between plasma coated pistons in solid forms with a liquid form of moly.

 

[JHZR2]

Originally Posted By: Trav
If that's the case then why bother with high HTHS? I don't know just a question.
This is what i don't understand..
Quote:
Liqui-Moly has established an excellent reputation for using MoS2 in high HTHS applications without any deposit problems.



Its not a matter of not messing with it. HTHS has to do with behaviors and film strengths in specific locations... My point about settling is more or less that those conditions dont exist.

That said, one other concept - in the locations where there is an applicability for high HTHS, if there is dispersed MoS2, the locations will act like a grinding mill. They will break the particles further.

Higher HTHS lubricants will retain a higher film strength there, preventing that sort of scenario.

If the particles are not milled, their sizes will not get smaller. When particles mill down, other forces such as DLVO can come into play, which can actually create an asymptotic particle size increase past some point. So if youre playing with grinding particles, exposing new surfaces with different chemistry, they may be prone to a different agglomeration characteristic, which forms hard deposits.

So the "protective" MoS2 layer, is in fact being harmed and when harmed, is creating bad byproducts.

Which defeats the purpose of using this add vrsus a higher HTHS oil to begin with.

Which is the result that many typically see anyway...

 

[19jacobob93]

One thing I did notice was that even after shaking the bottle of MoS2, it always comes out gray at first and almost black towards the bottom and you can see the different concentrations semi mixed in as it is poured. It seems to settle out slightly in the bottle so it could do the same in an engine that isn't used much

 

[Trav]

Originally Posted By: JHZR2
Originally Posted By: Trav
If that's the case then why bother with high HTHS? I don't know just a question.
This is what i don't understand..
Quote:
Liqui-Moly has established an excellent reputation for using MoS2 in high HTHS applications without any deposit problems.



Its not a matter of not messing with it. HTHS has to do with behaviors and film strengths in specific locations... My point about settling is more or less that those conditions dont exist.

That said, one other concept - in the locations where there is an applicability for high HTHS, if there is dispersed MoS2, the locations will act like a grinding mill. They will break the particles further.

Higher HTHS lubricants will retain a higher film strength there, preventing that sort of scenario.

If the particles are not milled, their sizes will not get smaller. When particles mill down, other forces such as DLVO can come into play, which can actually create an asymptotic particle size increase past some point. So if youre playing with grinding particles, exposing new surfaces with different chemistry, they may be prone to a different agglomeration characteristic, which forms hard deposits.

So the "protective" MoS2 layer, is in fact being harmed and when harmed, is creating bad byproducts.

Which defeats the purpose of using this add vrsus a higher HTHS oil to begin with.

Which is the result that many typically see anyway...


Thanks for the explanation JHZR2. I am still running this over in my mind.

 

[dailydriver]

Originally Posted By: Trav
This 3800 GenII is turbocharged and although run on synthetic oil it was mostly pre GF-5 with a HTHS of about 3.1. Later i started using HTHS 3.8 in it but most of the deposits were probably already formed.


GN/GNX/T-Type/Turbo TA, or some sort of turbo kit/setup on an originally NA 3800?

 

[Shannow]

Originally Posted By: JHZR2
Its not a matter of not messing with it. HTHS has to do with behaviors and film strengths in specific locations... My point about settling is more or less that those conditions dont exist.

That said, one other concept - in the locations where there is an applicability for high HTHS, if there is dispersed MoS2, the locations will act like a grinding mill. They will break the particles further.

Higher HTHS lubricants will retain a higher film strength there, preventing that sort of scenario.

If the particles are not milled, their sizes will not get smaller. When particles mill down, other forces such as DLVO can come into play, which can actually create an asymptotic particle size increase past some point. So if youre playing with grinding particles, exposing new surfaces with different chemistry, they may be prone to a different agglomeration characteristic, which forms hard deposits.

So the "protective" MoS2 layer, is in fact being harmed and when harmed, is creating bad byproducts.

Which defeats the purpose of using this add vrsus a higher HTHS oil to begin with.

Which is the result that many typically see anyway...


I agree wholeheartedly with your logic...low hths oil, thinner oil wedges, more physical contact, indeed higher shear stresses across the particles just due to hydrodynamic forces.

The rest of the oiling system and sumps etc. are playing in the regular kinematic viscosity range, so HTHS is irrelevant to the physics of them dropping out.

 

[Shannow]

Reading the article a few more times, I think that the writer has the bull by the wrong horn...the attributes that he's ascribing to MoS2, friction modifiers, anti-oxidant, and "falling out of solution" (note, no suspension) are more related to the soluble Molys (DTC etc.) than the solid particles.