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

[Gokhan]

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 direct-injection (TGDI) engines. Currently VW 504.00 is the only spec that tests for IVD.

Engine Oil Components Effects on Tu...Gasoline Turbocharger Deposit Protection

CONCLUSIONS

The following conclusions can be made:

1. Based on previous [2] and current findings, dispersants, antioxidants, and viscosity modifier have an effect on GMTC test response. Any impact from molybdenum level on GMTC test response appears to be minimal.

2. No correlation between the GMTC test response, measured as the percent increase in TCO temperature or average turbocharger deposit merit rating, and total deposits measured in TEOST 33C was observed.

3. Passing and failing TEOST 33C oils resulted in no significant difference in engine sludge and turbocharger deposit ratings in gasoline turbocharged vehicles under field driving conditions.

 

[d00df00d]

Now that's interesting. Thanks for posting.

 

[1JZ_E46]

Is the GM turbo test only part of Dexos? Or also API?

 

[buster]

Quote
It turns out that TEOST 33C test is useless for judging turbocharger protection.


Agree. Toyota also came to the same conclusion. The TEOST 33C test is more of a bench/screening test. The Honda Hot Tube Test (HTO-06) came out in 2006 as Honda also felt the TEOST test was not indicative of real world performance. The GM Turbo test is most recent and what is being used for turbo testing.

Mobil also has their own proprietary test:

"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."

https://mobiloil.com/en/article/why...performance/mobil-1-turbocharged-engines

 

[Gokhan]

Originally Posted by 1JZ_E46
Is the GM turbo test only part of Dexos? Or also API?

Only dexos. It's called GMW17299.

 

[wemay]

Very interesting, thanks for sharing

 

[Gokhan]

Here is the data on how different types of VII, amount of antioxidant, dispersants, and amount of moly affect the turbocharger deposits. It's interesting that they didn't bother to study the effect of different types of base oil. Note that there are two measures: turbocharger coolant outside temperature (TCO temperature) percent increase and end-of-test deposit merit ratings.

The type of the VII and amount of antioxidant makes a day-and-night difference.

The new Mobil 1 Turbo Power oil (M1 TP) apparently claims 3% on the TCO test (4x better than the 13% limit). Virtually all M1 flavors are dexos1 Gen 2 certified and it's unclear if the other flavors are different in the TCO performance. Note that the Test Oil B had less than 1%, which is about 16x better than the 13% limit, outperforming the M1 TP by yet another 4x.

 

[crainholio]

This is a real conundrum...turbos dislike moly, but timing chains like moly.

 

[dave1251]

Originally Posted by crainholio
This is a real conundrum...turbos dislike moly, but timing chains like moly.



If timing chains are designed and manufactured to quality not cost it does not matter. I'm not sure turbos dislike molybdenum rather than moly does not positively affect turbos.

 

[Gokhan]

Originally Posted by crainholio
This is a real conundrum...turbos dislike moly, but timing chains like moly.

On the contrary, one of the conclusions of the paper is that moly, even in extreme quantities (~ 1000 ppm), has minimal effect on turbocharger deposits.

 

[Gokhan]

Also note that the star-type VII, which is high-shear-stable, increases the deposit formation greatly. The authors attributed to that it has poor oxidative stability and increases the rate of oil degeneration.

Olefin copolymer VII, which is mid-shear-stable, did much better in preventing deposits.

 

[Colt45ws]

It does affect it, but so little its not worth worring about. However this is over 1000ppm moly? Even the biggest BITOG moly-head I think would admit thats a LOT of moly.

 

[dave1251]

Originally Posted by Colt45ws
It does affect it, but so little its not worth worring about. However this is over 1000ppm moly? Even the biggest BITOG moly-head I think would admit thats a LOT of moly.



Nope there are guys who are dead set if motor oil does not have 3000PPM of ZDDP and 1500PPM of moly it's a weak goberment mandated oil which is mandated against "protection". One posted about this within the last 3 months.

 

[StevieC]

Interesting. Thanks Gokhan.

 

[Gokhan]

The authors noted that the reason why moly doesn't affect the real turbocharger as much as in TEOST 33C is because the temperatures are much lower: 190 - 275 °C in GM turbochargers or less in modern turbochargers with the engine coolant circulating around the oil-cooled bearing area vs. 480 C in TEOST 33C. Moly decomposes at 300 °C.

The authors call the high moly (7x or 9x the typical treat level and much greater than 150 ppm) being at the truly friction-modifying level.

 

[Colt45ws]

Originally Posted by dave1251
Originally Posted by Colt45ws
It does affect it, but so little its not worth worring about. However this is over 1000ppm moly? Even the biggest BITOG moly-head I think would admit thats a LOT of moly.



Nope there are guys who are dead set if motor oil does not have 3000PPM of ZDDP and 1500PPM of moly it's a weak goberment mandated oil which is mandated against "protection". One posted about this within the last 3 months.

Aw, we still havent moved past that several decades later? Ah well. Guess Im too hopeful.
I did also find it interesting about the high shear stable VII causing a worse result than the mid-shear stable. Goes to show you cant get the best of everything.

 

[PimTac]

Originally Posted by Gokhan
The authors noted that the reason why moly doesn't affect the real turbocharger as much as in TEOST 33C is because the temperatures are much lower: 190 - 275 °C in GM turbochargers or less in modern turbochargers with the engine coolant circulating around the oil-cooled bearing area vs. 480 C in TEOST 33C. Moly decomposes at 300 °C.

The authors call the high moly (7x or 9x the typical treat level and much greater than 150 ppm) being at the truly friction-modifying level.




I wonder if this applies to tri-nuclear moly? I could see having large amounts of the older forms to be a hindrance at some point of ppm.

 

[SonofJoe]

Wow!

Until now, you've the world's biggest (only?) advocate of TEOST testing! Now it appears you've had your own personal epiphany and concluded that the test is useless; something us 'industry dropouts' have been saying for years.

You do realise that good science requires a degree of CONSISTENCY or did they not teach you that at PhD school?

 

[Gokhan]

Originally Posted by SonofJoe
Wow!

Until now, you've the world's biggest (only?) advocate of TEOST testing! Now it appears you've had your own personal epiphany and concluded that the test is useless; something us 'industry dropouts' have been saying for years.

You do realise that good science requires a degree of CONSISTENCY or did they not teach you that at PhD school?

When did I claim that TEOST 33C correlated with OEM turbocharger deposit tests? I did claim that there might be a correlation with direct-injection intake-valve deposits (IVD). Show me a paper that says otherwise and I'll stand corrected.

You're the one by the way who made the false claim that IVD were not correlated with the SAPS level.

 

[BMWTurboDzl]

What did I take away from this article? With regards to turbocharging one should use an oil which has a narrower viscosity spread in order to limit VII. In my case it would be a 5w30 and avoid the 0w40.