NOACK vs TEOST

[blingo]

Well, today that would most often be Polyisobutylene or Polyisobutene for google, and primarily in low smoke two stroke oils. http://www.basf-petronas.com.my/sites/default/files/BPC - HR PIB_final_Nov 17.pdf
Bigger brochure with handy tables has INEOS https://www.biesterfeld.com/fileadmin/documents/product/Indopol_Polybutene_Bulletin_07-07.pdf

For Le Mans obviously the molecular weights had been lower as they'd only used it for the chambers and not in the sump. Common two stroke oils would employ more viscous grades like HR-PIB 1000 or PIB 950. And as VII or thickeners in gear oils the viscosities / molecular weights would be much higher again. But in gear boxes the lines between VII and base become blurred anyway it seems: https://www.morrislubricantsonline.co.uk/lodexol-mtl.html
Beyond they also work as tackifiers and glue or to seal windows and roofs, and in aero fuels are meant to work as anti misting additives, I guess. There's also been talk about adding PIB or PB to diesel fuel for efficiency, actually prepared from solids to be dissolved, if I remember that right. A product – no idea, what to think of it: http://www.visconusa.com/nbc-2011-11-02

Otherwise to me it's quite fascinating stuff in a few ways, but it probably never took off as a "brightstock replacement", at least I never could identify a current four stroke PCMO or HDEO with the codes for it. An older Bel-Ray had one of the CAS-numbers, that's about it https://radelmarket.ru/upload/iblock/27f/safety_raylene_blend_10w30_engine_oil.pdf

 

[blingo]

Much less of an answer from me regarding the polyol-ester. Yes, their findings then were unfavourable. But I cannot say how much better they might look today or how much better POE could have been supported even then. Sometimes it looks as if right above test temperatures they might do all sorts of things, depending on your choice of contaminants, metal passivation and general magic. The testing may be one thing, the engine without closed loop for 275°C on hotter sides of things another. Whatever next then. Clinging to metals, ready to decompose / further polymerize, watching fuel and flames flying by, even having old fuel and stuff in the own mix.

Google is quick to advise replacing half of your esters for oven chains and engine oils with AN when after lower formation of residues. Personally I'm just thinking about repairing or not repairing my rotary – not a chemist, I regret. Haven't even got a talent of asking knowledgeable people :-(
You'd have to do that for me

Regarding the Noack and depositing I'd expect most oils the observation was based on to be low on ester bases. Esters appear basically off topic here.

 

[OilUzer]

My specialty is in asking knowledgeable people. However, my problem is not listening to them sometimes. lol

Thanks for the info.

 

[blingo]

Another document I come across now has several interesting pages (here p.133 ff, 5.3 Vent Pipe Simulator) with unknown turbine oils in not a thin film coker but a different two phase deposition test. One picture from it might provide good illustration, if my wording was bad enough, why I'm not too impressed by TEOST MHT (and some PAO/ester fan culture in general): https://etheses.bham.ac.uk/id/eprint/5423/

To the left an oil said to be known for low deposition is shown for five different temperatures. Then to the right five high performance candidates with even lower deposition at 325°C are also shown – among which "HPC 1" at just 350°C behaves much worse than the standard performance reference oil.
TEOST 33c for TC shafts in this regard would be more exhaustive by varying temps, but MHT or panel coker testing at just one medium temperature setting not support generalisation well. High temperature stability itself seems to become a part of what's unfortunate a handful of °C / K above – and testing therefore quickly becomes deceptive. Unless all TEOST are already considered to be mostly worthless...

 

[buster]

Deposits are tricky and usually more additives lead to more deposits, but it really is more complicated than that.

There are better tests for testing turbo deposits that take into account the aging procedure (used oil) that simulates additive consumption and sludge/soot build-up.

Joe90Guy was not fan of it claiming " PS - Forget TEOST. It's won prestigious awards for being The Most Stupidest Lubricant Test Ever Developed "

 

[Tom NJ]

There are many different deposit or "coking" tests for lubricants. Most fall into one of two categories: static or dynamic. In a static test, the oil is baked on a metal or glass surface until it evaporates or solidifies. Then the deposit is weighed, and often touched or pushed with a finger to determine the stickiness or fluidity of the deposit. The most infamous of static tests is the old "aluminum dish" test (or sometimes "paint can lid" test) in which a small amount of oil is added to a small dish and then baked in a forced air oven at some arbitrary temperature and time. This test is very common among smaller independent oil companies because it is fast and free to run. However, I have never seen evidence that it correlates to any real world application - in fact, just the opposite. More sophisticated static coking tests may be useful for some applications.

In a dynamic test the oil is reapplied to the test surface by dripping, spraying, or pumping - conditions encountered in most lubricant applications. Temperature, time, flow rate, metallurgy, and humidity are carefully controlled and deposits are evaluated by weight and visual examination. Properly designed, dynamic coking tests correlate very well to deposit formation in high temperature applications, such as jet engines, industrial oven chains, and reciprocating air compressors. The tests are more expensive and complicated to set up and therefore more commonly seen in larger laboratories by companies participating in lubricants for high coking applications.

Because the oil is reapplied in a dynamic coking test, the oil has the opportunity to wash the test surface and thereby potentially dissolve oxidation by-products and deposit precursors. Such tests often favor polar oils which have greater solvency characteristics. In our testing we found Group I based oils to produce less deposits than Group III based oils, and PAO based oils were even worse. This is one reason why all jet engine oils worldwide are based 100% on expensive POEs with no PAO or Group III base oils. POAs are great in bulk lubricant environments, but depending on the formulation can be deposit formers in thin film high temperature environments. Adding esters, ANs, or detergents can help mitigate this tendency. As always, it's the finished formulation that matters, not just the base oils.

The key to any coking test (or any test for that matter) is that correlation is established to actual field data using reference standards. The TEOST test appears to be a dynamic test, but I never ran the test or dealt with its data so I cannot comment on it. It appears the test was properly correlated to field data at the time it was developed some 25+ years ago. Whether it still does with modern engines or turbochargers, I really don't know.

 

[wpod]

"All oils are exactly the same but different" Squeaky Dave

 

[buster]

Thanks Tom, great response as always.

 

[blingo]

So, basically the value of POE depends on not leaving their window of comfort, naturally. Within ~25K lubes could go from ~60% less in deposits to ~120% more (the VPS example oils). I'm trying to not make it up, just take it from some paper, very roughly.

And for a lubricant making it to the top ring, to intake valve stems or into combustion chambers, onto apex seals etc. we have to forget about TEOST. These points of lubrication or just contamination don't see much flow (essentially no recirculation), no atmosphere easily simulated and no upper temperature limit. The extent of just ring land that could really be covered by the 285°C TEOST MHT would be small for anything but a stationary engine in very controlled conditions. Idemitsu saw some applicability of its 280°C TFC thanks to the Le Mans weather forecast knowing enough about
the temperatures over 24h. And after correlating engine testing. The TFC for a 9000rpm engine on the same day and course might already have differed.
We're debating "high quality base stocks", "performance" or "thermal stability" most of the time as if advertising text modules with just slight seasonal adjustment would put us ahead for final dismantling.
In the end it may be perfectly fine to just drop names of ester oils for cleaning purposes or cleanliness up to oil scraper rings or so. Beyond these or some point of no return down the PCV and intake, however, there'd be a realm more for basic Conradson testing or whatever. Approvals included of course.
TEOST certainly could be extended for a few more millimeters of coverage by laying a finger on oils' "break" points right beside loud data points that seem to indicate some "quality performance stability" when in fact they are relevant to almost nothing in vehicle engines. Buying 60% less and getting 120% more after all shouldn't be that small print all around

 

[Gokhan]

We are looking at a 40-year-old iffy, obscure paper here. Since when POE causes engine deposits? Who knows what went wrong in that paper. They didn't use the proper antioxidant? They used a very unstable POE? More importantly who cares?

Tom NJ is right on that there are many oil-deposit tests and they may or may not correlate with actual engine deposits. TEOST 33C was recently shown not to correlate with turbocharger deposits at all.

GM turbocharger test: No correlation for deposits with TEOST 33C or moly

It turns out that TEOST 33C test is useless for judging turbocharger protection. Antioxidant is the key, along with the VII (or the lack of it) and dispersant. Moly has no effect. However, I think TEOST 33C may be better correlated with intake-valve deposits (IVD) in turbo gasoline...

www.bobistheoilguy.com

Regarding moly it's interesting that moly is not what causes the deposits in TEOST 33C but it serves as a catalyst to form deposits. This is why SAE 0W-16 and SAE 0W-20 are exempt from TEOST 33C in ILSAC, as Japanese OEM's like to load them with high moly content, such as 600 ppm Mo or above, and such high-moly oils would fail TEOST 33C, despite performing very cleanly in an actual engine.

TEOST MHT is no longer used as far as I know.

Both TEOST 33C and TEOST MHT use a catalyst (a different type in each) to induce deposit formation. This is probably why it is so hard to correlate them with actual engine deposits. They may be more useful for screening purposes when designing oil blends.

buster is right that the additives, detergents, dispersants, and VII also play a major role.

There is some truth to some extent that higher Noack reduces deposits as the oil evaporates faster before it can deposit. Thinner oils also have lower aniline points and better solvency. However, if higher Noack also means inferior base-oil quality, this could increase the deposits.

As for the polybutylene, it does evaporate extremely cleanly, without leaving deposits. However, it looks like it's only available in very high viscosities, such as KV100 ~ 20 cSt; therefore, you would only see it in some monograde etc. applications. It is used as a replacement for bright stocks—high-viscosity Group I base stocks, as these are becoming less and less available as solvent-refining to make Group I base oil is being abandoned.

Coming back to POE, Valvoline Premium Blue Restore is specifically designed as a maintenance oil to clean the carbon deposits around the piston rings in one oil-change interval. Its base oil has 62.5% POE.

Here is the Valvoline Premium Blue Restore formulation.

Formula #4 is what is sold commercially.

Priolube™ 1973: an 8.00 cSt POE by Croda
Synesstic™ 12: a 12.4 cSt AN by ExxonMobil
D3495L: a detergent–dispersant–inhibitor (DDI) package by Infineum
PX-3871: a mixed alkyl borate ester additive for dispersancy, antiwear, and friction modification (antifriction) by Dorf Ketal

It's unlike any other oil. Valvoline Premium Blue Restore has:

Base-oil composition: 62.5% (50/(50+10+15+5)) POE (ester), 25.0% ((15+5)/(50+10+15+5)) PAO, and 12.5% (10/(50+10+15+5)) AN (alkylated naphthalene)
No viscosity-index improver (VII) at all—a monograde oil
Standard Valvoline Premium Blue Synthetic HDEO additive package (20% of the finished oil)

Therefore, unlike what that old paper reported, POE, with its extremely high solvency and extremely low aniline point, does a better deposit-cleaning job than any other base oil.

Euro Mobil 1 oils (FS and ESP varieties) also use POE for better cleaning of diesel engines as well as meeting the severely extended Euro oil-drain intervals.

 

[blingo]

Never questioned solvency or an aniline point. You just seem to look at nothing but TEOST 33c while mine was mostly about very different conditions in engines themselves, not turbochargers, later then about VSP and implications. I was not at all against Tom's entries. He did differentiate between testing that see's POE washing off and other testing that cannot see such. I did differentiate between a few millimeters up and down a piston where the lubricant can go from 60% less deposits to 120% more deposits within a delta of 25 Kelvin. Or worse, if accepting the reasoning for Le Mans 1991.
Which of course can become historized, but the main problem persists that from MHT you learn about some cleanliness ranking for an arbitrary temp as if you only looked at the 325°C in this VSP – where they drew a line for making up a "break point" that you wouldn't even claim for the blue oil without the reference line as it actually behaves better than the yellow oil from about 333°C onwards without looking much like suddenly breaking.

If viscosity curves were that disparate you wouldn't accept discarding KV40 and HTHSV150 for a single KV100 value that can only be relevant in very chosen points of lubrication of a given engine. You didn't like the 280°C TFC from 1991 but would face the same problem with the 275°C TFC from Croda of the 21st century as an engine beyond the oil scraper rings or hitting intake valve necks is in no closed loop for constant 275°C.

333°C minus 325°C equals 8K – about as much as the variations of some closed loop could look like anyway.

So this TEOST has to be something for something but basically irrelevant for practically all of our ideas. Unless they're focused on just some solvency somewhere...

 

[Gokhan]

On the contrary, in my post I was saying that TEOST 33C, TEOST MHT, and other bench deposit tests were usually irrelevant to actual engine deposits.

Can an engine oil have excellent cleaning (solvency, detergency, dispersancy, etc.) properties, such as that of a high-quality, properly balanced POE-based oil, but yet cause excessive carbon buildup as you seem to be suggesting? That doesn't make sense to me.

A lot has changed with engine oils since 1991—for example they didn't even have the HTHS viscosity in the oil specs back then.

 

[blingo]

I'm aware of ester products being said to brush right throughout combustion chambers, only yesterday I scrolled through http://d1-chemical.com/contents/download/37/294 (https://sod1plus.com/)

If it would work out the same when treating my engine on the autobahn? Whatever possible variations of results, there's nothing to be determined without exhaustive engine testing from just TEOST + ester + bold quality performance stability print anywhere, I regret. That's all. The 4 ball wear on the other hand...

.-)

 

[Tom NJ]

I would be interested in the source of the data above. Vent tube coking is a common problem in jet turbine engines, and the product designations of SPC (Standard Performance Capability), HPC (High Performance Capability), and HTS (High Thermal Stability) are all categories of POE based jet turbine oils, so presumably all of these products are fully POE based formulated oils.

There are certainly differences among POEs with respect to coking tendencies. POEs with long linear fatty acids (C8-C10+) have a higher reactive hydrogen factor and will lead to higher coking tendencies in turbine engines, while fatty acids with multiple branches and/or lower carbon lengths have a lower reactive hydrogen factor and have lower coking tendencies. The reason for this is the hydrogens on the acid's methyl groups are the most oxidatively stable, those on the second carbon are about four times less oxidatively stable, and the hydrogens along the acid backbone are about 15-20 times less stable. Hence the coking tendencies of the POE base oil varies significantly with the structure of the fatty acids used. I have a patent (now expired) that discusses this and was utilized in the development of a jet turbine oil that is considered the standard in the industry for low coking.

Low Coking Esters

Naturally the additives also play a substantial role in the coking tendencies of finished turbine oils, and the products used in the data above were likely fully formulated given the oil designations. SPC turbine oils generally use some non-alkylated anti-oxidants which are more deposit prone, while the HPC and HTS oils generally use fully alkylated amine anti-oxidants, and some use oligomers of these which are the cleanest. Among the top selling jet turbine oils in the world, one uses a POE which is rich in long linear fatty acids with some non-alkylated anti-oxidants, and another uses a POE with shorter and branched acids with oligomerized alkylated anti-oxidants, and the coking tendency difference between these two oils is well established in the laboratory and the field.

Therefore I would not draw any conclusions from that data presented above with respect to the coking tendencies of esters as a class.

 

[blingo]

Tom, in case you meant this page 144, all I could offer was this .pdf from above really https://etheses.bham.ac.uk/id/eprint/5423/
Haven't even read it all yet and wouldn't know more about their references.
I'm not for condemning esters per se. It's just that one cannot expect the lube on rings or apex seals, intake valves or piston crowns or rotor sides to remain this side of its shift. That's why I asked for a temperature range or test temperature early on.
This VPS in the .pdf for example was considered imprecise for the higher temps, so the test itself in fact must be regarded as out of range for lube making it that far through combustion/expansion and exhaust. Still, for heading to Le Mans 2021 or returning to the autobahn it could be of as much use as the TFC then (if well correlated to an aspect in engine testing or two).
I'm only opening the papers I can find for hints to esters' decomposition properties. Much testing for turbine engines would be about preferably just not seeing them decompose at all, I guess, as long as you can have a return line from there. Thank you very much for showing this!

 

[blingo]

Having read the patent now, I don't want to unfairly narrow down anything, but am really stuck with table 4 of course. Which happens to underline the questioning of some reasoning or TEOST MHT & some of its interpretation: As just a BITOG visitor

for a "piece of 300°C machinery" or point of lubrication I now might want to chose something like the TECH from line two,
for a piece of 309°C machinery or point of lubrication I'd obviously want to chose something like the TECH from line four, but be gambling (unless further information supported the choice),
and for a 316°C point of lubrication or most any piece of machinery from a bike engine to a jet turbine I'd see no idea left from just the table.

The table is not from a sales brochure of course, but at the same time is very much data much reasoning or fan culture can be based on. After all its like twice the testing (compared to TEOST @285°C) for just a handful of similar base oils.


I'll have to read or reread some files with more of that hydrogen counter in mind now. Still undecided if much thermal stability (instead of clean decomposition, "clean burn"...) is what I'd look for in case of some oil consumption, oil infusion of a two stroke / rotary or even just a tendency to develop consumption / deposition with some Volkswagen engines or the like.

 

[Gokhan]

Therefore I would not draw any conclusions from that data presented above with respect to the coking tendencies of esters as a class.

This is an understatement.

Here is an excerpt from Leslie R. Rudnick's authoritative book on synthetics. Esters are some of the most thermally and oxidatively stable base oils. Especially when they are optimized, which is the case with any decent commercially available ester base oil today, their stability is unsurpassed. (See Table 3.13.)

As I said earlier, Mobil 1 uses a "thermally stable ester" in its Euro (FS and ESP) oils, which is for reducing the deposits, not increasing them.

Source: internal ExxonMobil document

 

[blingo]

Didn't Tom, in what you cited, tell us to not just look at esters as a class and be completely right at it? Why not try the same for different areas of an internal combustion engine? Could help to not claim too much cleanliness from filler neck to exhaust pipe.

On intake valves a just thermally stable ester may have a good time and do a good job: If I come on over and sit down in your engine's intake to watch your ester oil arriving at the valve, dissolving, deterging/dispersing for a little while and then leave – I'm completely fine with that. I wouldn't even ask where it would go from there taking crud with it, and what it would want to do next. Just be fine for just the valve I see.
Now you come on over and sit down in my engine to watch portions of same oil arriving at piston grooves or rotor grooves, going up and down or round and round for a little while until evaporated or polymerised / incompletely burnt / otherwise ending up as residues – whatever comes first. A different picture. A tougher challenge.

Two files from last google night:

Petrochem has a few pics of different thermal stabilities that may help to really look at formation of deposits in the direction of the working chamber.

https://petrochem1.com/wp-content/uploads/FOODSAFE-APPLICATION-REPORT-PETRO-GARD-FG-220/Petrochem_FG-Ester_PAO_WMO-Brochure-Development.pdf

Their open cups for 240°C / 20h show the expected relations for a white oil, PAO and an ester product. Then for 240°C / 44h evaporation becomes extreme for the white oil and deposits become extreme for the PAO product. Very much the same within 20h for 260°C.
The ester product does much better. But they go on and look at an inclined coker panel @400°C. Now the higher thermal stability of the ester product just allows its drops to run down the panel further and even drip off. As far as they can make it that far this may translate well to some esters "cleaning" intake valves. As far as they don't make it that far and instead form deposits in the puddle this may point to deposition on piston rings and rotor seals for example. Which is what you actually see in an engine and could have cost the win at Le Mans.

The second file was even older and iffier I could swear, looking at lubricants for "low heat rejection" diesel engines running at elevated temperatures. https://core.ac.uk/download/pdf/42787965.pdf
At first that meant "sump temperatures approaching 250°C" but soon they went with 120°C. Primary focus was on "satisfactory service up to a top ring reversal (TRR)" of elevated temperatures. That's one half of the paper's beauty, the other half is the mentioning of the polymeric esters (as the or some POE were not deemed that promising then, but polymer esters were (besides some aromatic esters)). Akzo points to the Ketjenlube range mentioned earlier for known cleaner decomposition. (Somewhat cleaner I'd understand, nothing like PIB probably.) No use in boiling down their trials now of course. But to whom invalids may concern... just so much of them not seeing it all in thermal stability only:
" Very low levels of carbon were detected in these upper cylinder deposits. This was attributed to the intrinsic property of the aromatic base stock to decompose cleanly at the high temperatures of this engine test. This property also suggested that the aromatic esters would contribute less to the lubricant contribution of particulate emissions. "

Still not questioning plain solvency, dispersancy/ detergency or thermal stability. It's the principal shift from all that to a matter of clean decomposition, clean burn or whatever one may want or not want to call it, whenever nearing working chamber temperatures. Petrochem had no weights of total residues noted for the 400°C inclined panel, but at least they'd shown some of the potential where oil won't drip of (completely). From a piston ring groove or rotor seal groove it won't easily drip off as a solvent that takes some sludge with it.
Very different things happening between filler neck and exhaust pipe. That's why there are iffy papers, two stroke oils, alky naphthas,.. Just no aromatic esters anymore, I think. Any hints or documentation regarding cleanliness from polymeric esters and whatever could be welcomed instead of calling things plain iffy one doesn't like. Been there, read that before, haven't we?

ExxonMobil also points to AN for reducing piston deposits btw. As if pistons were oven chains. Not saying they'd work out in my case, rotors are no oven chains. But that's what I have by now – have to avoid POE and have AN in a pic. Would really love you to show anything.
But again, whenever you read something about deposition, you have to check what precisely they're talking about. They're never talking about a total from valve cover to exhaust tip. And they're reducing them as soon as they're reducing them in the valve cover, even if that means more deposition somewhere else.

Might be 400 / 300 without PAO to begin with, who knows? It ain't all in solvency and thermal stability, we have to accept.

 

[buster]

"The ExxonMobil Proprietary Thin Film Oxidation Test involves preheating the metal surface and the oil to high temperatures, and then continuously spraying the oil onto the metal surface. This test measures the oil’s ability to demonstrate varnish control within the high-temperature turbocharger environment. Oils with poor thermal stability will decompose, leaving behind a residue on the metal. Residue buildup could cause the temperatures inside the turbo to increase, eventually blocking oil passages and resulting in turbo failure."

GM Turbo test is another.

 

[blingo]

The rotating discs are a great demonstration of just some thermal stability. Not including much of a turbo's problems of course. Likewise not all areas in an engine itself are well represented by a rotating disc under the sun where the oil is meant to have a chance of making it over the edge, falling off tangentially before getting too seriously hurt.
They help us to rethink perceptions gained from brochures etc.