Audi A6 2.0 TDI: Biodiesel Compatibility & Details

Hello everyone,

I'm new here and I'm reaching out with a very specific question. Don't worry, it's not about "support for EB** junk" . Just a request to the lobbyists right from the start: please, no fundamental discussions about whether biodiesel is useful or not, or whether (used) oil might be better, etc. That's not of interest here, okay?

The point is: I have now driven a VW Golf III (factory approved, no problems) for 8 years / 220,000 km using biodiesel out of conviction. Now I have ordered an Audi A6 2.0 TDI pump-nozzle, which, unfortunately, is no longer approved by the manufacturer for biodiesel. Audi wrote this to me:

Quote:

Quote: From Audi, written on November 30, 2004 The new Audi A6 is not factory-approved for operation with biodiesel. However, we are already working on a special biodiesel package. However, a corresponding retrofit is not currently planned.

Okay, so, currently there is no factory approval, and there is also no option for a kit (195 EUR) that is available for other vehicles (e.g., A3 Sportsback). Now, one naturally wonders what the difference is between, for example, A3s with a bio-kit and those without, considering that the VAG group has been selling cars with biodiesel-compatible fuel systems for almost 10 years (excluding Bosch-VEPs ).

Therefore, my questions are:

"Can a specialist in this forum tell me exactly what the difference is between the new versions with and without the biodiesel package? Is this just technical jargon, or is Audi actually starting to install fuel lines again that are not made of fluorocarbon rubber (aka Viton), just to save a few cents, and are they charging a premium for the Viton versions?"

2. Since I'm determined to use biodiesel in my new A6 (even if it voids the warranty), but I'm not looking for trouble and the customer service hotlines aren't providing any information, could someone here who knows what they're talking about tell me which parts I need to replace with more resistant materials?

"3. Pump-nozzle engines no longer have a conventional fuel injection pump; therefore, the notorious problem of fuel injection pump leaks (a common issue with older engines) is eliminated in pump-nozzle engines. Are there any concrete experiences from people familiar with pump-nozzle technology? I've only found vague speculations or bold claims through Google searches."

No one who could actually know will give you a well-informed answer. Even Audi itself (i.e., the customer service hotline) only writes what they are allowed to write. The local VW workshop manager is extremely conservative. For him, biodiesel is inherently something to be avoided, and the local mechanics are just happy if they know where the other mechanic put the cordless drill. Therefore, it would be great if someone here could provide me with detailed information .

Thank you for reading, and thank you for replying.

Hi, please refrain from fueling a common rail diesel engine with biodiesel. The problem here isn't that individual components might leak, but rather that your common rail injectors could fail due to insufficient lubrication. You're not dealing with a system operating at 130 bar; you have a system that operates at a maximum of 2050 bar, and that comes with specific manufacturing tolerances. I would save the money for a nice vacation instead of spending it on new injectors. Best regards.

Hi,

I always thought biodiesel lubricated well? Wasn't there a discussion back then, when the new sulfur-free city diesel engines were introduced, and many vehicles failed due to poor lubrication and lack of additives? The idea was that by adding biodiesel, you could easily restore the lubrication to a normal level.

I always thought biodiesel lubricated so well?

Biodiesel is quite a good 'solvent.' Are you sure you have thoroughly used Google and the forum search function?

Having personally experienced a costly issue with a combination of biodiesel and a Bosch fuel injection pump, I "was allowed" to delve into the subject matter. In my vehicle, the fuel injection control piston failed in a rather dramatic way, resulting in a significant repair (due to insufficient lubrication). The previous owner of my car drove approximately 90,000 km on biodiesel. When I bought the car, the damage occurred at 120,000 km...
The car was also approved for biodiesel by Audi, but the ESP system from Bosch was NOT approved for biodiesel.

This article describes it quite well.

http://home.arcor.de/sgrafen/salatoel/biodiesel/biodiesel.html

So, my advice: stay away from it!

PS: The repair cost me €700, even though I did it myself and used a used ESP .

Julian wrote:

Biodiesel is quite a good "solvent". Are you sure you have thoroughly used Google and the forum search?

Yes, rest assured that I have extensively used Google and the forum search. If I didn't know anything about the solvent properties, I probably wouldn't have mentioned the Viton seals and fluorocarbon rubber, would I? Besides, one thing has nothing to do with the other. There are also solvents that lubricate well.

So that you know what I'm talking about, here's a source.
http://www.innovations-report.de/html/berichte/biowissenschaften_chemie/bericht-5196.html

Quote:

Biodiesel is suitable as a lubricant in sulfur-free diesel fuels. This conclusion was reached by the Institute for Energy and Environmental Technology at the University of Rostock, which investigated novel lubricant additives for diesel fuels.

@wbuchi82:

I am familiar with all the stories about the missing pump authorization from Bosch. However, I would like to reiterate that we are talking about a pump-nozzle engine that no longer has a VEP. So please, let's get back to the topic, okay?

Well, the PD doesn't have just one fuel injection pump; it has four!

The report that I often share on this topic is the following:

http://www.braunschweig.ihk.de/innovation_umwelt/nachrichten/januar/Schlussbericht-Motorprueflauf.pdf

Adding just a few percent of a certain substance drastically increases nozzle coking, regardless of whether it's a PD or VP formulation.
The dilution of the engine oil due to biodiesel deposits is also significant.

I wonder why you're such a strong advocate for biodiesel: it's not environmentally friendly or cost-effective. Are you a farmer?

Nero24 wrote:

.... I always thought biodiesel lubricated well? ....

Yes, that is correct.
Unfortunately, the viscosity of the bio-additive is so poor that it can no longer effectively flush the injector nozzles (or the VP pump), leading to a significant reduction in lubrication. According to an internal research paper from a well-known diesel injection system manufacturer, the lubrication provided by the bio-additive is only about 20% of what is provided by diesel fuel. This clearly demonstrates the inferior lubricating properties.

Quote:

I am familiar with all the stories about the missing pump authorization from Bosch. But I would like to reiterate that we are talking about a pump-injector engine that no longer has a VEP (variable valve lift). So please, let's get back to the topic, okay?

Bosch is also not granting BD approval for the PD components!
What is the difference compared to a limited liability company (GmbH) then?

Julian wrote:

The report that I often like to share on this topic is the following: http://www.braunschweig.ihk.de/innovation_umwelt/nachrichten/januar/Schlussbericht-Motorprueflauf.pdf

What does the report have to do with our topic? The report is about the addition of unrefined rapeseed oil, not biodiesel! Biodiesel is transesterified rapeseed oil, and its molecular composition has about as much to do with pure rapeseed oil as diesel has with crude oil. It's like arguing that gasoline isn't good for an internal combustion engine because the spark plugs would coke up so quickly if you added pure crude oil .

Okay, seriously now: It can't be that we're already discussing the pros and cons of biodiesel again. I just wanted to know what the difference is between the models with a biodiesel kit and those without in the new Audi models.

But to answer your question: I'm a fan of biodiesel because...
- I drove it for 220,000 km without any problems.
- my Golf III didn't run any slower with it than it did with diesel.
- My Golf III, with this modification, averaged only a 0.3 l/100 km increase in fuel consumption over more than 8 years.
- Biodiesel is up to 20 cents cheaper than diesel with us.
- The raw materials used to produce biodiesel are not grown in crisis-affected regions.
- we (or rather, our children) will eventually stand like fools next to empty oil fields and wonder what to do next, when all the practical alternatives are constantly dismissed as nonsense.

Nero24 wrote:

Okay, seriously now: It can't be that we're already discussing the pros and cons of biodiesel again. I just wanted to know what the difference is between the models with a biodiesel kit and those without in the new Audi models.

Audi is obligated to insure the ESP systems with a third-party insurer against damages. Bosch will not provide any warranty for damages that can be proven.
BMW does the same thing.

Quote:

But to answer your question: I'm a fan of biodiesel because... - I drove it for 220,000 km without any problems. - my Golf III didn't run any slower with it than it did with diesel. - My Golf III, with this modification, averaged only a 0.3 l/100 km increase in fuel consumption over more than 8 years.

Lucky me.

Quote:

- Biodiesel is up to 20 cents cheaper than diesel with us.

Bei uns sind es gerade mal magere 6 Cent ... dafür den Ärger? NThank you!

Quote:

- The raw materials used to produce biodiesel are not grown in crisis-affected regions.

Since when have the North Sea and Russia been in a war zone?
D obtains 90% of its crude oil from these regions.
The crude oil from the war zones mostly ends up with our colleagues across the Atlantic.
By the way, biodiesel is heavily subsidized. The national debt continues to grow with every liter of biodiesel sold.

Quote:

- we (or rather, our children) will eventually stand like fools in front of empty oil fields and wonder what to do next...

Unfortunately, that will likely still be the case, even if we use BD.
The market share of domestically produced goods in Germany is significantly below the 2% quota required by the EU.

Quote:

.... if all practically viable alternatives are permanently dismissed as nonsense.

I would not consider this fuel to be practical for real-world use.

Here I am again...
I'm already aware that your A6 has a PD engine.
What I wanted to say is that the fundamental problem with biodiesel in relation to Bosch pumps (whether common rail or unit injector) hasn't changed.
I highly doubt that Audi would install different, more resistant common rail injectors for a biodiesel kit that costs €195. (Bosch doesn't even offer them).
"After I inquired about my incident with Bosch directly, I was even confirmed that the issue is related to the lubricating properties of biodiesel. And considering that there are four injectors, each operating at 2050 bar, I only need to add them together... This means that more resistant hoses, seals, and filters can be used... The problem lies with the injectors themselves."

@Nero24

Hello neighbor?!

I actually didn't want to get involved in this discussion, but after reading some of the things being said, I feel I have to add my two cents.
I'll accept your argument about renewable resources. What's not correct, as Bertil already pointed out, is that the oil in Germany comes from crisis regions. Also, with just a few liters of biodiesel, you won't prevent the oil sources from eventually running dry forever. What I'm curious about is this: you say you're concerned about ecology, etc. So why biodiesel? The amount of energy required to transesterify used oil is not insignificant. Where do you think that energy comes from? Right! Probably not from biomass! So, there's not much else left: nuclear power, coal, natural gas, oil... and whether that's really that ecological...
Furthermore, I'm also interested in what motivates someone to buy a car costing over €30,000 and then forgo the warranty due to insignificant amounts? Those 20 cents/liter are just a smokescreen, and I haven't thought that way for a long time, as you write. I travel a lot and pay very close attention to the BD price. Currently, it's between 6 and a maximum of 11 cents. I'm very curious to hear your honest answers, even if it seems off-topic to you.

I'm also part of the 'high-performance' group, and I'm probably using quite a bit of fuel in my Passat, but I definitely won't be putting any biodiesel in the tank.

@Julian
I don't want to question the research results from the link you posted, but I'd like to offer a few comments, if I may?
'In my opinion, the setup of these experimental series is quite questionable. The idle phases of 15 minutes before and after the measurement runs are highly suspect and, in my opinion, contributed to carbon buildup and oil accumulation. Furthermore, every experienced mechanic knows that the fuel injection/delivery should start early, not late.'
'I can tell you that I used a roughly 50:50 mix of fuel and biodiesel throughout the summer in my car. I drove approximately 15,000 km. Due to a problem with a 0-ring on a high-pressure pump (PDE), I replaced the entire set of PDEs in early October. I didn't observe any carbon buildup like the images in the report, nor could I confirm any oil increase. The 0-ring issue is known in VW vehicles with older PDEs, and I wouldn't attribute it to the biodiesel. Furthermore, after 6,000 km of using pure biodiesel in my dual-tank system in my winter A4, I haven't noticed any oil increase. I check the glow plugs (ESD) every 2,000 km, and so far, I haven't seen any signs of carbon buildup. In the spring, after the car has completed its winter season, I'll check the spark plugs, and then we'll see how things look in terms of carbon buildup, etc. My opinion of the report: It's not bad, but it contains many minor errors and inconsistencies that will likely deter those with limited knowledge. It's unclear who obtained the results...'

Hello Nero24,

You had already posted the same questions in another forum . Unfortunately, the opinion in this forum, which is actually very good from a technical perspective, is relatively strongly against BD.

Regarding the use of BD (presumably a specific term or product), I personally have issues with the statements made in this forum, as very little of it seems accurate to me.

You already recognized that the study mentioned above has nothing to do with Borderline Disorder (BD). Furthermore, half of the facts presented in the link mentioned earlier are simply incorrect regarding BD.

Regarding lubrication, the viscosity was considered. When comparing the standards for diesel and biodiesel (BD), the difference in viscosity is minimal.
Diesel: 2.0 - 4.5 mm²/s.
BD 3.5 - 5.0 mm²/s
PÖL - 38 mm²/s
The reduction in lubrication caused by oil leakage, supposedly by 80% (100-20), cannot be explained in this way. This is true when using process oil.
@Bertil: Could you please share the contents of the internal research paper? You can obscure any identifying information. I have a feeling that PÖL might have been tested here.

I already wrote to you that I suspect the RME option refers to the integration of a fuel sensor to meet EU4 standards. The fact that this option is still under development fits the picture well, as the necessary sensor hasn't been around for very long.

I understand Nero24's question very well. Everywhere on the internet, you read about defects in VEP (Variable Emission Plasma). There are hardly any reports of defective PD (Plasma Display) elements. I only ever read claims. Has anyone among you experienced actual, understandable cases of damage? Ideally, with a detailed description of the damage? If so, it would be very helpful if you could post about such cases. That would certainly make it easier for Nero24 and me to make a decision.


Regards,

Dirk.

Well, Jörg, I don't consider this article to be the ultimate masterpiece, but your approach to the vehicles is something that not every other BD car owner would do. You know what's important, and many others don't.

Gremlin repeatedly and correctly mentions the destructive effect of household use on materials. And for such applications, both BD and PÖL must be suitable, and in my opinion, neither of them can fulfill this requirement.

I question the ecological claims made by RME, and this has been independently confirmed on multiple occasions.

To stay on topic:

If this €195 kit actually exists, I would also expect changes to the seals and some hoses (flexible, temperature-resistant pressure hoses are expensive). However, the 'mechanics' of the PDEs (presumably referring to a specific component) cannot be changed, and therefore they remain susceptible to the BD (presumably referring to a specific problem or failure mode).
With such an expensive car, I wouldn't do that, or I would just buy a gasoline car (-> converted to natural gas) to improve the environmental balance.

@joergs

The energy balance of biodiesel is consistently positive, typically around 1:3 (ranging from 1:2 to 1:4 depending on the study).

@julian
I question the ecology of RME, and this has been independently confirmed on multiple occasions.
I would like to see this independent confirmation. I disagree (also independently). However, I believe we agree that the environmental impact of regular diesel is significantly worse than that of BD and PÖL. I think we need to start somewhere. I am aware, and I'm sure Nero24 is too, that BD and PÖL are not the ultimate solution.

Regards,

Dirk.

Dirk_S wrote:

.... @Bertil: Could you please share the contents of the internal research paper? You can obscure any identifying information. I have a feeling that PÖL might have been tested here. ....

Sorry, but I definitely won't risk my job for that.
Watermarks are difficult to remove.
BD was tested.

Quote:

Unfortunately, the opinion in this forum, which is actually very good from a technical perspective, is relatively strongly opposed to BD.

Probably because too many people who have been affected by the "Bonusdisziplin" (a German term referring to a specific type of penalty) have already written here. It's also possible that these types of problem cases are concentrated here. People who are having a good experience are unlikely to report it.

But let's be realistic for a moment:
Why would you risk damaging a sensitive high-pressure injection system (whether it's common rail or pump-injector) by using fuel that hasn't been approved by the manufacturer?
If reducing the lifespan of such a system by only 5% through BD means I haven't saved anything, then it's not worth it.