A deeper UOA question, need the heavyweights here

[Not the Autorx Frank]

Do different oils have different abilities to suspend wear particles? It seems to me that a used oil analysis W/ a higher ppm count of wear metals might just be due to the oils ability to hold them in suspension. This would also explain $1 oils outperforming $5 oils in some cases. The cheap oils may just be leaving all the wear behind? Just a thought? Please clue my in if my logic is absurd. LOL

 

[bigpaulo]

I think this is a very interesting question, and I'd love to see someone who knows better to comment on it.

 

[Dominic]

Its more likely a filter issue than an oil's ability to suspend particles issue.

 

[MolaKule]

It is the job of the DISPERSANT

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=21;t=000032

to suspend deposits, disperse soot and deposit precursors, and to keep HC polymers from aggregating. Soot (HC particles) and resins from various polymers, such as VII's, are pushed together and congregated by the polar action of the dispersant molecule.

The dispersant forms "micelles" which congregate these particles and hold them in suspension. It is similar to raking leaves into one pile and then stuffing them into a bag.

Most dispersants are Alkylsuccinimides and alkylsuccinic esters (alkenyl succinimides), usually Polyisobutenyl succinate esters.

Most modern oils have good dispersants and much has been learned about dispersants through improved chemistry. The amount of dispersant in motor oils is usually from 3% to 7% by weight, making it the highest among additives. In addition, the dispersant is the highest molecular weight component except for the viscosity improver.

Like any other component, the dispersant only has a certain lifetime, so oil drains or top offs replenish the dispersant.

Today, most of the dispersants for mineral oils are part of the Dispersant/VII package and are called "polymeric dispersants."

For full synthetics, the ester bases usually take on the job of dispersants.

I'll put this summary in the Question of the Day section as well for posterity.

[ December 03, 2004, 10:49 PM: Message edited by: MolaKule ]

 

[Gary Allan]

Okay ..you've dazzled us with brillience ...now for the baffled ...


btw-some of the language used for dispersants appeared very close to floculation and chelation.

Anyway....how does one determine whether ones dispersant is doing its job ..or, instead, you're depositing all the "stuff" that should be in the oil to be read by a used oil analysis?? How do we now that we're seeing wear particle production ..or merely wear particle retention??

..and how does "seating" fix into the mix??

For the moment ..imagine explaining it to a teenager ..that wasn't chemistry's version of Bill Gates.

 

[Jay]

We've had this discussion before on this board. Some members were arguing that the good UOA reports on 20-weight oils were because the metals were "settling out" of the thin oil. We decided that the particles that FTIR analysis "sees" are so small that they're colloidal and never settle out. There's a direct, linear relationship between wear and the amount of extremely tiny particles (
[ December 03, 2004, 11:43 PM: Message edited by: Jay ]

 

[Gary Allan]

Well assuming, for lack of spending any more time finding a definition for colloidal, that this means ultra fine particles in suspension, that indeed mass quantities of particles can be settling out all the time ..and we use these "colloidal" particles since this is the only indicator that we have available to us.

That is, we're lacking in any "absolute" indicator ..so we settle for what's practical and available.

 

[Gary Allan]

Without needing the .0000000000000000000000000001" definition we can concede that it is very small.

quote:

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colloidal

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Might I inquire who "We" is, pale face?

(vision of the Lone Ranger and Tonto surrounded by multiple hostile tribes. Lone Ranger says, "Looks like we've had it here, Tonto. Tonto says, "What's this "we" $hit, whiteman?")

 

[Jay]

An angstrom is 1 x ten to the -10th power. The wavelength of a beautiful green laser I used to work on was 5320 angstroms.

Here was the thread I mentioned. It was one of the better threads on the forum, I thought.

 

[Not the Autorx Frank]

Ok dare I say exactly what I was thinking LOL. I am just suspect that looking at a used oil analysis without knowing the chemistry of the oil itself is somewhat faulty. If you have an oil with great disperants it MAY show higher ppm in wear elements as opposed to an oil with very poor dispersants.

For Gary

colloidal

A system in which finely divided particles, which are approximately 10 to 10,000 angstroms in size, are dispersed within a continuous medium in a manner that prevents them from being filtered easily or settled rapidly.

now if soeone could let me know what an angstrom is?

 

[XS650]

quote:

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now if soeone could let me know what an angstrom is?

[/QB]

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1 angstrom= 10,000 barn^.5

 

[widman]

Going back to the original point - I have seen it. I did an comparison analisis on two trash trucks, one continued to use the cheap oil, and the results were seeminly amazing. But the engine was full of sludge and mud. First column is the cheap oil, second is Delo
Visc 11.60, 14.70
TBN Mag. 30, 54
Calcium 88,2848
Phos. 80,1108
Zinc 74, 1157
iron 86, 62
lead 7,4
copper 3, 3
Chrom 7, 3
Alum. 2, 7
Silicon 1, 12

Both were run 611 hours collecting trash in a small town, both identical trucks.

In the end they said it didn't matter how they took care of the trucks, if they broke down and the trash piled up all over town, CNN would cover it and some country would donate new trucks.

 

[Jay]

DNS, good catch. Angstroms are fractions of meters.


palmerwmd, I don't understand your post. I thought all inexpensive oil analysis was done by FTIR spectroscopy. Is FI-AAS the same as gas chromatography?

Getting back to the topic, Let's assume, just for argument's sake, that one oil with a better dispersant package is able to hold more wear metals in suspension than another oil. And let's further assume that these wear metal particles can be read by oil analysis. I still don't think it would make any difference in UOA results because samples are drawn hot (or should be), right after shutdown, and the metals that can be detected would be all mixed up in the oil anyway--dispersant package or no.

 

[WeyounDS9]

quote:

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Originally posted by Jay:
DNS, good catch. Angstroms are fractions of meters.


palmerwmd, I don't understand your post. I thought all inexpensive oil analysis was done by FTIR spectroscopy. Is FI-AAS the same as gas chromatography?

Getting back to the topic, Let's assume, just for argument's sake, that one oil with a better dispersant package is able to hold more wear metals in suspension than another oil. And let's further assume that these wear metal particles can be read by oil analysis. I still don't think it would make any difference in UOA results because samples are drawn hot (or should be), right after shutdown, and the metals that can be detected would be all mixed up in the oil anyway--dispersant package or no.

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Jay:

FT-IR can't be the right technology used from what I know it does (I work use it every week).

I suspect someone mistyped the analytical isntruments used at some point or another ,and it got picked up.

GCMS ("GC") and AAS are the main technologies to get the the kind of results used oil analysis look for.
Also titration for the TBN.

Fred..

 

[MolaKule]

quote:

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Do different oils have different abilities to suspend wear particles? It seems to me that a used oil analysis W/ a higher ppm count of wear metals might just be due to the oils ability to hold them in suspension.

---

The deposits I spoke about are not wear metals. The deposits that dispersants disperse and hold in suspension are those HC's that would eventually turn into sludge if the oil was not drained or the dispersant replenshied.

A base oil's ability to suspend wear particles comes from a rule of thumb that says the smaller the metal particle the more likely it is to stay suspended in the oil. In physical terms, if the wear particle has a lower density than the oil, it will become "bouyant" and stay in suspension.

Unless the oil filter can trap it, it will most likely stay in suspension or be "whipped" back into suspension by the turbulence of the oil.

If a fully formulated oil has better AW and lower friction capabilities, then that oil should produce lower wear particles in the same engine. The base oil(s) combined with the proper additive package would determine that.

 

[DNS]

quote:

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Originally posted by Jay:
An angstrom is 1 x ten to the -10th power. The wavelength of a beautiful green laser I used to work on was 5320 angstroms.

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More specifically, an angstrom is 1 x 10 to the -10th METERS

 

[Not the Autorx Frank]

Mola,

So we really have 2 issues here?

1. Sludge prevention

2. Wear prevention

The key is finding an oil that does both well. The factors are:

Filtration

Base Oil

AW package

There may be oils that prevent wear well for a while but eventually start to form sludge. (conventional) There also may be oils that never create sludge but have slightly higher wear.(RL etc)

Some would argue M1 as the best compromise etc.

Thank you for the discussion everyone...very good comments here and I learned some new exciting vocabulary

 

[WeyounDS9]

Jay,

Not FT-IR.

FT-IR is Fourier transform Infrared which uses a substances bonds, absorbing infrared light to make an absorbance ( r sometimes transmittance) spectrum, which can tell you about the functional groups involved and it can also be matched to a library.

FTIR is does not have much usefulness, in Motor oil analysis, as it is unable to resolve mixes, unless you have a library match and even then there would have to be enough chemcical differences for even the Fourier transform algorithm to have something to latch on to.

It is absolutely unable to detect metal ions floating in solution as those dont bond with anything and even if they did, the oil molecules bonds would mask whatever absorbance you might get.

A good method for detecting metal ions in solution if FI-AAS, Flame Ionization Atomic Absorbance spectroscopy.
This is an excellent detector of metal ions in a mixture as it uses a flame to ionaize the metal and the spectral response give information on the type and amount of metals ions present.

Fred...