NOACK - Carbon Build up - A40?

[FlyPenFly]

Is it still the prevailing thought that intake carbon buildup comes a lot from NOACK properties of an oil?

About to get my intake valves walnut blasted on my Macan S (128k mi, V6 twin turbo), I mostly use M1 0w40 FS. Will probably just stick with that and 5k intervals (filter 10k). But I'm curious if there's a diff oil I should consider that's A40 or as good as A40 and has lower NOACK.

 

[dnewton3]

I certainly think that the decision would be better made AFTER the IVD cleaning. Ask them (presuming you're having it done professionally) to take some pictures to document the deposits; see how "bad" they are. You may find that the Mobil 1 is adequate, or not; won't know until ya look!

 

[FlyPenFly]

I certainly think that the decision would be better made AFTER the IVD cleaning. Ask them (presuming you're having it done professionally) to take some pictures to document the deposits; see how "bad" they are. You may find that the Mobil 1 is adequate, or not; won't know until ya look!

Yeah, it's not a big problem right now, I see a bouncy idle when cold which is what I saw in previous BMW DI engines I owned that were from carbon buildup. Just getting ahead of it before the problems becomes worse.

There's also some people on the Macan Forums with mileage similar to mine that took pics and seems to be still an issue with this engine.

 

[CarDoc66]

I’m so glad my Toyota has D4S.

Back on the late 80’s we had cold start stalling on Volvos with the B230 engine. Massive intake valve deposits would soak up the gas on the first squirt in the AM.
We used walnut shells back then and I will say the valve was shiny clean after.

 

[twX]

From what I can gather, NOACK doesn't seem to have a large effect on valve deposits. Engine tests where the PCV system doesn't vent to the intake show little improvement in valve deposits.

Larger factors seem to be the VII content of the oil, especially with aged oil. Deposits increase with more VII. A 0W-40 will contain a lot of VII, and a 5W-30 or 5W-40 would probably result in cleaner valves.

 

[FlyPenFly]

From what I can gather, NOACK doesn't seem to have a large effect on valve deposits. Engine tests where the PCV system doesn't vent to the intake show little improvement in valve deposits.

Larger factors seem to be the VII content of the oil, especially with aged oil. Deposits increase with more VII. A 0W-40 will contain a lot of VII, and a 5W-30 or 5W-40 would probably result in cleaner valves.

Interesting, more reason to switch to a Motul 5w40? Not sure what the differences are between their 5w40 offerings. Maybe their "XCESS-Clean" might be better for my use?

 

[Brian123]

From what I can gather, NOACK doesn't seem to have a large effect on valve deposits. Engine tests where the PCV system doesn't vent to the intake show little improvement in valve deposits.

Larger factors seem to be the VII content of the oil, especially with aged oil. Deposits increase with more VII. A 0W-40 will contain a lot of VII, and a 5W-30 or 5W-40 would probably result in cleaner valves.

If that is the case, lets all use 10W-30, just Kidding. Now, with the VII thing, I thought it was more of an issue with the quality VII that were being used and the Base Oil. What I am trying to say is an oil like Mobil 1 FS 0W-40 is maybe going to leave less deposits than a cheaper 0W-40. I do not know what the cheaper ones are since I only look at 2 oils at this time, Mobil 1 and HPL.

 

[shortyb]

Always a lively discussion when talking about the causes of IVD. Lots of folks like to blame certain properties of the oil such as SAPS, NOACK, VII, additive amounts, etc. At the end of the day it probably comes down more to overall design of the system that deals with oil vapors, ie; PCV, breathers, separators et al. Some are better than others. Add direct injection to the mix (almost all now) and it just adds insult to injury when there is no fuel wash on the intake valves to help with cleanliness. My approach is to use the "cleanest" oil I can, such as VW 504/507, make sure my breathers are functioning properly, and drive the snot out of my cars. Incidentally, when I did a valve cleaning on the 145K CCTA engine with somewhat "regualr" oil change history, the valves had a good bit of deposits on them. Did not impact smoothness, idle, or drivability, so was there any real need for concern if they were gooped up? Probably not so much.

 

[twX]

If that is the case, lets all use 10W-30, just Kidding. Now, with the VII thing, I thought it was more of an issue with the quality VII that were being used and the Base Oil. What I am trying to say is an oil like Mobil 1 FS 0W-40 is maybe going to leave less deposits than a cheaper 0W-40. I do not know what the cheaper ones are since I only look at 2 oils at this time, Mobil 1 and HPL.

The base oil and VII type might matter, but the test below shows that the oil that has the highest VI and the highest quality base oil (Group IV PAO, 0W-30) had more valve deposits than the lower-VI Group II or Group III oils, at least once the oil was aged.

Here's another figure from an older study using PFI engines (SAE 932792), showing a strong correlation between VII content and valve deposits:

 

[BMWTurboDzl]

Is it still the prevailing thought that intake carbon buildup comes a lot from NOACK properties of an oil?

About to get my intake valves walnut blasted on my Macan S (128k mi, V6 twin turbo), I mostly use M1 0w40 FS. Will probably just stick with that and 5k intervals (filter 10k). But I'm curious if there's a diff oil I should consider that's A40 or as good as A40 and has lower NOACK.

Back around 2007 Europe moved to ULSD and ULSG. Around that time Lubrizol, additive supplier, produced a presentation which claimed reduced amount of deposits on ACEA C3 (low Saps) oils. These oils were only allowed to be used with ULSD/ULSG. A40 is based on ACEA A3.

The US moved to ULSG around 2020. BMW and IIRC Mercedes have been using Low-SAPS oils for a couple of years now. There is Porsche C40 (VW 511.00) spec which is a Low-SAPS oil in 40 grade. If you're looking to experiment you could try a C40 oil combined with UOA's to see how the it's holding up. It's also worth looking to see if Porsche back spec'd your car for C40.

mobil 1 esp x3 0w 40

www.mobil.com

 

[TiGeo]

Is it still the prevailing thought that intake carbon buildup comes a lot from NOACK properties of an oil?

About to get my intake valves walnut blasted on my Macan S (128k mi, V6 twin turbo), I mostly use M1 0w40 FS. Will probably just stick with that and 5k intervals (filter 10k). But I'm curious if there's a diff oil I should consider that's A40 or as good as A40 and has lower NOACK.

I've never seen any actual data to support this relationship. Intake valve cleaning is simply a maintenance item on any DI engine no matter the oil, fuel, or whether you run a catch can or not.

 

[buster]

It's hard to say if any oil can mitigate them at all. There have been a few posts in the past about what oils could potentially help reduce them, but it has not been proven.

 

[FlyPenFly]

Yeah, it seems like there's no solid evidence and maybe it varies per engine and oil contributes nothing? Maybe it's all just from combustion blow by.

 

[TiGeo]

Irs just oil/fuel laden fumes back through the PCV and onto the valves pressurized by combustion blow-by.

 

[SubieRubyRoo]

Irs just oil/fuel laden fumes back through the PCV and onto the valves pressurized by combustion blow-by.

BuT cAtCh CaNs DoN’t MaKe A dIfFeReNcE!! say the doubters… the analysis of my catch can goop over the winter shows it’s the lighter fractions of the oil, along with a good bit of the additive package. Without fuel to wash this off the valves in real-time, IVD is as guaranteed as taxes and death.

Minimizing the vapors in the PCV system will help regardless of the engine, but isn’t a guarantee that the valves won’t need cleaning at some point.

 

[TiGeo]

BuT cAtCh CaNs DoN’t MaKe A dIfFeReNcE!! say the doubters… the analysis of my catch can goop over the winter shows it’s the lighter fractions of the oil, along with a good bit of the additive package. Without fuel to wash this off the valves in real-time, IVD is as guaranteed as taxes and death.

Minimizing the vapors in the PCV system will help regardless of the engine, but isn’t a guarantee that the valves won’t need cleaning at some point.

I have never seen direct evidence that catch cans do a thing vs. not having one w/r to IVDs on the MK7 VWs at least. Worthless in my view. YoUR rESulTS maY vaRY.

 

[OVERKILL]

The base oil and VII type might matter, but the test below shows that the oil that has the highest VI and the highest quality base oil (Group IV PAO, 0W-30) had more valve deposits than the lower-VI Group II or Group III oils, at least once the oil was aged.

View attachment 207077

Here's another figure from an older study using PFI engines (SAE 932792), showing a strong correlation between VII content and valve deposits:

View attachment 207080

Them making up a winter grade does not fill me with confidence (7.5w-30).

 

[chris719]

Until someone shows data with massive differences I won’t choose an oil based on theorized IVD reduction. You can clean valves but you can’t undo wear. Even in the worst engines for IVD most people would only have to do the cleaning once or twice during an extended ownership period. It seems like PCV design dominates the effect anyway. BMW N54 has far worse deposits than N55 running the same full SAPS oil. I doubt there’s any oil you can put in an N54 and make it as clean as an N55 over the same period.

 

[TiGeo]

Until someone shows data with massive differences I won’t choose an oil based on theorized IVD reduction. You can clean valves but you can’t undo wear. Even in the worst engines for IVD most people would only have to do the cleaning once or twice during an extended ownership period. It seems like PCV design dominates the effect anyway. BMW N54 has far worse deposits than N55 running the same full SAPS oil. I doubt there’s any oil you can put in an N54 and make it as clean as an N55 over the same period.

This. MK7 VW far better than previous gens w/r to IVD....better PCV...same oils.

 

[weasley]

The base oil and VII type might matter, but the test below shows that the oil that has the highest VI and the highest quality base oil (Group IV PAO, 0W-30) had more valve deposits than the lower-VI Group II or Group III oils, at least once the oil was aged.

View attachment 207077

Here's another figure from an older study using PFI engines (SAE 932792), showing a strong correlation between VII content and valve deposits:

View attachment 207080

This kinda correlates with the Mazda Renesis (rotary) engine deposit formation claims that led to Mazda issuing a bulletin not to run synthetic oil in the Renesis engine. This further led to a lot of misunderstanding and confusion because in Japan only Group IV is considered "synthetic" (rather like Germany), so group III is actually OK (as evidenced by their use of a Group III oil as the Mazda genuine oil), but the rest of the world were convinced that you couldn't use Group III and were saying only mineral oils (Groups I and II) were allowed. FWIW I ran a group III in my RX-8 with no issues.