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Sorry, I think you misunderstood or I wasn't very clear. Never had LSPI and I've never seen it "in the wild".
Maybe you are referring to that I had my timing chain stretched severely at 75K miles on my turbocharged direct injected engine (not my Mezger, my Audi 2.0T). I attribute this to soot formation and having to use the dealer for oil changes while my car was under warranty (even though Lake says you can use any oil you want I agree with Charles that it could cause you trouble if you're not careful YMMV on that one). I have switched to Driven DI40 with 5K OCI's now that it's my choice and I suspect I will never have this problem again (I'll let you know). The timing chains have also been updated as well several times and you can see this visually. Audi and Porsche share many of the same parts and technologies.
What I am trying to say is that LSPI is exacerbated by turbocharging the engine but according to industry research it isn't exclusive to it. However it's not a frequently occurring phenomenon. Related to my point above, soot formation is much more of an issue. Direct injection technology is great in so many ways but not in every way; one downside is that it creates particles that when looked at using a special technique closely resemble those that would be found in a light diesel engine. This is what people should be worried about IMHO.
Yes. But my memory of our discussion was that you stated that it was LSPI that caused the timing chain damage to your turbocharged Audi engine.......which was the reason for my confusion. Thank you for explaining.
This is interesting stuff. I have a 2017, so turbocharged, and from the tech bulletin, the recommended oil is A40 and not C40 (same for the boosted Macan's).
Take this for whatever you think it's worth: On my 2002 911 TT Mezger engine (not directed injected) I did 5K OCI's and the oil came out looking what I would consider normal from seeing other cars before it. However, on my turbocharged direct injected Audi 2.0T I run Driven DI40 -- that stuff looks very clear like water when I pour it in. And when it comes out at 5K (or even at 2.5K when I short changed it after the timing work) it looks like India Ink -- very dark. I have never seen oil that gets so dirty so fast until I bought a direct injected engine. I still like direct injection technology but my cylinder walls are cast iron so I don't have to worry about bore scoring which is a very real threat with Alusil and even Nikasil. This is why I am considering a 991.2 right now but car prices are too high.
LSPI would not damage a timing chain, that doesn't make sense, but soot formation can and will. I have seen it first hand; you should have seen how much it was "stretched". I am not saying LSPI doesn't exist -- industry research like I posted above shows does and can even affect a naturally aspirated engine. I'm just saying I don't think it's that likely to. I consider it a "nice to have" benefit of DI40 rather than a primary reason I run the oil.
Thanks for your expanded explanation. Here is what I think it is worth: You assign 100% blame for your dirty oil on the direct injection. I think your fault assessment is misplaced. The dirty oil is most likely caused by the turbocharger pressures pushing contaminates past your oil ring in one or more cylinders. Forced induction substantially increases cylinder pressures. Those increased forced induction cylinder pressures are most likely pushing fuel/air and/or carbon past one or more rings and trashing your oil. That is why it is black. Contamination of lightly used, low mileage, oil as you describe is caused by carbon, soot, fuel/air, etc. being pushed past a piston ring whether caused by a bad top ring, bore scoring or whatever. Increased cylinder pressures of forced induction exacerbate the issue. You might consider a compression test and regular UOAs.
I have previously owned three, port-injected, NA flat sixes and currently own three, direct injected, NA Porsche engines. The oil in the direct injected engines looks the same in the direct injected engines as in the port injected NA engines at my 5k/6 month oil change interval…..always a light brown,……never black.
The 2002 911 TT is forced induction, so then why wasn't the oil as dirty per your explanation? I did a UOA, it was perfect after I found all the errors, Charles knows all about it but we won't go into that again as we have already done that. My compression is fine, it's not blow-by and my crankcase vacuum is exactly where it needs to be -- but you can think it is if you want to........ everything I am saying is documented in both industry and academic research. Many of the articles you have to pay to read but if there's a will there's a way.........
Soot agglomerates extracted from engine oil from a modern gasoline direct injection engine have been characterised for the first time, with the aim of assessing size, distribution and shape. The nanostructure of the primary particles was also investigated. A robust methodology to produce samples for TEM and HRTEM was developed and outlined.
Agglomerate size was given in terms of skeleton length, width and fractal dimension. At the macro scale, the GDI soot agglomerates are remarkably similar to agglomerates from light duty diesel engines as reported in the literature. The mean length and width were found to be 153 nm and 59 nm. 54% of the agglomerates presented an aspect ratio <2.5, indicating a small predominance of compact structures with very modest branching. The mean fractal dimension of the agglomerates was calculated to be 1.44.
Conversely, the primary particles differ in nanostructure from a typical diesel soot particle. GDI primary particles are spherical in shape, with some irregularities. The mean diameter was found to be 36 nm. An inner core and outer shell structure was found in the majority of the particles. The wider graphitic layers concentrically orientated, and typically with fewer reactive sites, were covered by an amorphous 5 nm layer with very short segments.
Volatile lamellar graphitic structures were found deposited on the external surface of soot-in-oil primary particles. TEM-EDX analysis of non-soot nanoparticles in the sample showed the widespread presence oil additive elements and wear metals.
The 2002 911 TT is forced induction, so then why wasn't the oil as dirty per your explanation? I did a UOA, it was perfect after I found all the errors, Charles knows all about it but we won't go into that again as we have already done that. My compression is fine, it's not blow-by and my crankcase vacuum is exactly where it needs to be -- but you can think it is if you want to........ everything I am saying is documented in both industry and academic research. Many of the articles you have to pay to read but if there's a will there's a way.........
Soot agglomerates extracted from engine oil from a modern gasoline direct injection engine have been characterised for the first time, with the aim of assessing size, distribution and shape. The nanostructure of the primary particles was also investigated. A robust methodology to produce samples for TEM and HRTEM was developed and outlined.
Agglomerate size was given in terms of skeleton length, width and fractal dimension. At the macro scale, the GDI soot agglomerates are remarkably similar to agglomerates from light duty diesel engines as reported in the literature. The mean length and width were found to be 153 nm and 59 nm. 54% of the agglomerates presented an aspect ratio <2.5, indicating a small predominance of compact structures with very modest branching. The mean fractal dimension of the agglomerates was calculated to be 1.44.
Conversely, the primary particles differ in nanostructure from a typical diesel soot particle. GDI primary particles are spherical in shape, with some irregularities. The mean diameter was found to be 36 nm. An inner core and outer shell structure was found in the majority of the particles. The wider graphitic layers concentrically orientated, and typically with fewer reactive sites, were covered by an amorphous 5 nm layer with very short segments.
Volatile lamellar graphitic structures were found deposited on the external surface of soot-in-oil primary particles. TEM-EDX analysis of non-soot nanoparticles in the sample showed the widespread presence oil additive elements and wear metals.
Correct, blowby isn't the cause for this contamination. Soot contamination of engine oil in direct injected engines is a problem. What problems does this soot cause? Stretched timing chains.
I don't think anyone anticipated that gasoline direct injected engines would create as much soot as a modern diesel engine. That's why gasoline particulate filters are coming (and already required in Europe).
I've read most every SAE whitepaper related to GDI engines and LSPI. All these issues are very well documented.
Because the 2002 911TT does not have a ring issue which the other engine does have. Only the engine with the ring issue is showing the black oil after low mileage. Not showing up on compression test because normal compression test never reaches the high turbo pressures which is pushing the contaminates past rings at boost. Low mileage oil that goes from clear to black does so for a mechanical reason. Low mileage oil only turns black for one reason: contaminants from an engine cylinder are moving to the oil. That can only happen through the rings or valves. Highest probability is bad top ring in a cylinder. With all respect, I do not believe it is a direct injection-soot issue. Sounds like a ring issue that happens during high boost/pressure of forced induction. If it was direct injection issue only, everyone on Rennlist would have black oil at 5k miles instead of only you.
Charles hit the nail on the head I agree with everything he said (I was also going to mention the gasoline particulate filters, my wife is German and we go over there often). The short of it is that soot formation is well documented in GDI engines but it seems you already seem to have your mind made up otherwise. I didn't come here looking for an argument, only to offer my experience and knowledge after almost losing an engine. If you want to dismiss it and do otherwise I have zero problem with that and have at it. Your car, your money. I won't lose a second of sleep over it this weekend.........
I agree with Charles too especially concerning LSPI and NA engines. I just don’t think black, low mileage, oil is 100% a DI issue. You have something else going on which the general population of DI engines is not experiencing. I am not denying DI engines produce greater soot. I am just saying that soot alone and by itself does not cause “India Ink” black oil at 2.5k miles. I have 3 DI engines and I do not see it. Have a nice weekend.
Hi Charles: So as a follow-up, I have a 2019 911 GTS. My last oil change was performed at the Porsche dealership 10,000 mile free service and they used M1 0W40 (A40). Since this vehicle is turbo charged am I correct to assume that for longevity of the engine it would be most beneficial to be using C40 spec motor oil? If so anything special to do or just switch on next oil change? Still under warranty so I would still need to use a a Porsche approved oil. Thanks in advance. PS I’m in the USA so no particulate filter.
I agree with Charles too especially concerning LSPI and NA engines. I just don’t think black, low mileage, oil is 100% a DI issue. You have something else going on which the general population of DI engines is not experiencing. I am not denying DI engines produce greater soot. I am just saying that soot alone and by itself does not cause “India Ink” black oil at 2.5k miles. I have 3 DI engines and I do not see it. Have a nice weekend.
My 991.2 1000mi drain of Mobil 5w50 was black, as were all the previous Mobil drains. Motul 8100 Excess 5w40 (gen2) 1000 mi drain looked like it just came out of the bottle! Both drains had a track day on them.
My 991.2 1000mi drain of Mobil 5w50 was black, as were all the previous Mobil drains. Motul 8100 Excess 5w40 (gen2) 1000 mi drain looked like it just came out of the bottle! Both drains had a track day on them.
Good data point, thanks. One school of thought on this would be that dirty oil is "better" in the sense that it indicates that the detergents and other agents are doing a good job of peptizing the soot and keeping the insoluble portion suspended in the oil you are draining and noticing to be visually dark; as opposed to agglomerating and staying in the engine as those carbon particulates are good at hiding in crevices etc.
My 991.2 1000mi drain of Mobil 5w50 was black, as were all the previous Mobil drains. Motul 8100 Excess 5w40 (gen2) 1000 mi drain looked like it just came out of the bottle! Both drains had a track day on them.
Agree. My point is that turbocharger pressures in cylinder push more contaminates past rings. You have a turbo’d 991.2. I do not see black oil @ 1k miles on NA DI engines (991.1).
Good data point, thanks. One school of thought on this would be that dirty oil is "better" in the sense that it indicates that the detergents and other agents are doing a good job of peptizing the soot and keeping the insoluble portion suspended in the oil you are draining and noticing to be visually dark; as opposed to agglomerating and staying in the engine as those carbon particulates are good at hiding in crevices etc.
Any other thoughts/explanations? And would that out weigh the benefits of 300V - better UOA's, 1-2 mpg increase in steady state 170 mi drives, and subjectively a smoother engine?
07-09-2021, 04:01 PM
