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BMW Diesel Owners / Enthusiasts
Do you own a diesel powered BMW? Maybe a 335d or a BMW x35d? Come and talk about what makes your car great!

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  #1  
Old 05-19-2013, 07:56 PM
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finnbmw finnbmw is offline
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Biodiesel content and your warranty

My apologies if this has been discussed prior, but I saw this interesting article http://www.thedieseldriver.com/2012/...your-warranty/
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  #2  
Old 05-20-2013, 05:35 AM
KeithS KeithS is offline
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Article is a bit misleading in their example of the Mercedes owner where they said:

"Several months ago, the Illinois-based owner of a 2009 Mercedes-Benz R350 BlueTec reported a two thousand dollar repair bill to "clean the engine and intake manifold from the residue left over from using B20 diesel fuel for 90K miles," pointing out that this is "the only diesel fuel available in the state of Illinois!"

From the knowledge gained from this board and others, I'm pretty sure that the B20 had nothing to do with the "residue" which we call carbon buildup. I'm not suggesting everyone go out and start using B20 either. Bottom line is we really have little control over the bio content of the fuel we are using.

Last edited by KeithS; 05-20-2013 at 05:44 AM.
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Old 05-20-2013, 05:46 AM
TDIwyse TDIwyse is offline
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Thanks for posting that.

There are pros and cons with all fuels. It's good to learn the tradeoffs of what you put in your property. However, I noticed a lot of things in there that are incorrect or speculations portrayed as facts. Speculations without science to test the claims are a pet peeve of mine.

In an attempt to try to give some balance on this let's consider a few examples to follow.

The very first sentence is factually incorrect.

Five years ago, biodiesel was a form of fuel that the diesel enthusiast would convert his or her vehicle to use.

5 years? Uhm, no. "Converting" the vehicle to use it? No. Biodiesel has been around a lot longer than that. I was buying it commercially ~15 yrs ago.

http://www.biodiesel.com/index.php/b...biodiesel_fuel

This following claim is funny to me.

Several months ago, the Illinois-based owner of a 2009 Mercedes-Benz R350 BlueTec reported a two thousand dollar repair bill to clean the engine and intake manifold from the residue left over from using B20 diesel fuel for 90K miles, pointing out that this is the only diesel fuel available in the state of Illinois!

Direct injected engines utilizing EGR have intake manifold clogging issues, both gasoline and diesel variants. It's the unfortunate nature of emission control schemes. We've seen this in the VW TDI community for many years on vehicles that haven't used biodiesel. We've seen this in the 335d community as well. We've seen it in the 335i community... and the list goes on.

And then there's issues in this paragraph as well:

Modern diesel passenger cars currently being offered in the U.S. were designed to use B5, or 5% biodiesel content; as a consequence, using blends with as much as 20% biodiesel have caused problems ranging from check engine warnings to reduced fuel economy and outright engine failure. In addition, the manufacturers warranties on these cars support the use of only up to B5, which was the biodiesel standard when the cars were engineered to meet U.S. and especially California Emissions standards. The move towards higher biodiesel content fuel has the unfortunate side effect of, putting the consumer on the hook for the cost of repairs which can be rather expensive.

The Chevy Cruze diesel, which has passed EPA official mileage ratings and going on sale, was designed to use and is warrantied for B20 use.

http://www.prnewswire.com/news-relea...190557151.html

Also, how has the author verified the cause of these problems is biodiesel related? People get the same problems with pure petroleum fuel. Trying to scientifically control all the variables to prove that statement would be a challenge. I'd like to see the science that supports the conclusion.

Also, no vehicle warranty covers damage from bad fuel. For example, There's all kinds of cases of people filling up at diesel pumps that actually had gas in it and caused engine damage. The warranty doesn't cover this, the fuel stations insurance would be the one to cover this.

There's other issues in there as well, but this should hopefully give some balance to what appears to me to be an alarmist article with a lot of unsubstantiated claims.

Oh, and the author fails to mention problems with US petro diesel. There's concerns over fuel lubricity. Our US fuel spec for lubricity is higher than Europe, and what fuel injection manufacturers want for the fuel pumps, which lowers the expected lifespan of the HPFP. So sticking with straight petro diesel has its problems too it is out of spec from a HPFP point of view...

http://www.globaldenso.com/en/topics...tion_paper.pdf

Lubricity: It is essential that the lubricity of the fuel as measured by the HFRR test specified in ISO
12156-1 meets the requirement of a wear scar diameter not greater than 460 microns. In addition, it is
recommended by the Diesel FIE manufacturers, that first fill of the fuel tank should be with fuel with
good lubricity characteristics (HFRR < 400 m) in order to guarantee good run-in of the injection system
components. The US diesel specification (ASTM D 975-09) includes a lubricity value of 520 m maximum
(according to ASTM D 6079). It is expected that the useful operating lifetime of any mechanical
component will be adversely affected by fuel with a lubricity exceeding 460 microns
.


And TDIclub has some links to random sampling VW did of fuel around the US as it struggled to contain the HPFP failures it was seeing with its new TDI's (and there's a federal investigation still going on of that) and an alarming number of samples had lubricity values above the already high 520um spec limit.

Pros and cons to all fuel choices...
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  #4  
Old 05-20-2013, 08:14 AM
Pierre Louis Pierre Louis is offline
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There are many possible causes of HPFP failures even though there are those that wish they could prove the lubricity argument. Although fuel pump manufacturers understandably push for better fuel lubricity, the HPFP data so far seems to fail to support this claim. A substantial percentage of fuel found was of good lubricity when HPFP failures occurred, while a good percentage of HPFP "failures" included no defects in the fuel pump at all. The most likely culprit seems to be gasoline contamination in the tank when the HPFP failure occurs, but this does not explain it all.

PL
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Last edited by Pierre Louis; 05-20-2013 at 08:16 AM.
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Old 05-20-2013, 10:21 AM
TDIwyse TDIwyse is offline
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Originally Posted by Pierre Louis View Post
There are many possible causes of HPFP failures even though there are those that wish they could prove the lubricity argument. Although fuel pump manufacturers understandably push for better fuel lubricity, the HPFP data so far seems to fail to support this claim.
I'm sorry, but that's just not backed up by the science.

http://www.arb.ca.gov/fuels/gasoline...22003bosch.pdf

Page 12 shows a quantifiable analysis on life expectancy of the HPFP vs lubricity. Lower lubricity quantifiably, measurably and verifiably reduces the life of the pump. To say otherwise is simply ignoring reality. And there's a dramatic and sharp reduction in life above 450um. One tank of really low lubricity fuel can significantly impact the lifespan.

Quote:
Originally Posted by Pierre Louis View Post
A substantial percentage of fuel found was of good lubricity when HPFP failures occurred, while a good percentage of HPFP "failures" included no defects in the fuel pump at all. The most likely culprit seems to be gasoline contamination in the tank when the HPFP failure occurs, but this does not explain it all.

PL

Just because the particular fuel in the tank at the time the car had a HPFP failure may have had acceptable lubricity tells us nothing about the fuel that was used in it previously. It's a long term, statistical failure cause, and relying on what's in the tank at the moment as a basis to conclude what it had in there previously is, well, poor failure analysis. That would be like concluding that an obese man who has a heart attack while exercising with a stomach full of a salad had been practicing good dietary and exercise habits for the preceding years of his life (when he could have been a smoking, over eating coach potato).
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Old 05-20-2013, 10:53 AM
TDIwyse TDIwyse is offline
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Some of the official background data as an FYI for those who may not be familiar.

http://www-odi.nhtsa.dot.gov/acms/cs...003-54326P.pdf

From pg 30 (lots of out of spec fuel out there that can reduce the life of the HPFP).

827 diesel fuel samples have been acquired throughout the continental U.S.
In respect to viscosity, 203 samples were out of ASTM specification (below 1.9 cSt), 186
of those were below the HPFPs nominal threshold of 1.5 cSt. Here the HPFP may not
have been properly lubricated.
59 samples were detected with lower lubricity (greater HFRR/WSD value) than required.
22 of them exceeded the HPFPs nominal tolerance of 570m and may have caused
increased wear.
4 samples were found to contain increased amounts of water more than 1.5 % / 1.8% /
2.5 % and one sample exceeding 10% of water, which was not detected in the fuel
station and random vehicle surveys. Viscosity and lubricity are within specification, but
water could cause rust and corrosion in the HPFP and damage the pump.
79 samples contained more than 5% biodiesel, 20 of those exceeded 10%. Biodiesel
itself does not damage the HPFP, however, collapsed/deteriorated/aged biodiesel can
cause deposits inside the HPFP and clog filters, interrupting the lubrication and leading
to failure.
252 samples showed a flashpoint below ASTM specification, but this has no direct
impact to the HPFPs durability and may just be seen as an indicator for possible
gasoline content.
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  #7  
Old 05-20-2013, 12:03 PM
BMWTurboDzl BMWTurboDzl is offline
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Quote:
Originally Posted by TDIwyse View Post
Some of the official background data as an FYI for those who may not be familiar.

http://www-odi.nhtsa.dot.gov/acms/cs...003-54326P.pdf

From pg 30 (lots of out of spec fuel out there that can reduce the life of the HPFP).

827 diesel fuel samples have been acquired throughout the continental U.S.
In respect to viscosity, 203 samples were out of ASTM specification (below 1.9 cSt), 186
of those were below the HPFPs nominal threshold of 1.5 cSt. Here the HPFP may not
have been properly lubricated.
59 samples were detected with lower lubricity (greater HFRR/WSD value) than required.
22 of them exceeded the HPFPs nominal tolerance of 570m and may have caused
increased wear.
4 samples were found to contain increased amounts of water more than 1.5 % / 1.8% /
2.5 % and one sample exceeding 10% of water, which was not detected in the fuel
station and random vehicle surveys. Viscosity and lubricity are within specification, but
water could cause rust and corrosion in the HPFP and damage the pump.
79 samples contained more than 5% biodiesel, 20 of those exceeded 10%. Biodiesel
itself does not damage the HPFP, however, collapsed/deteriorated/aged biodiesel can
cause deposits inside the HPFP and clog filters, interrupting the lubrication and leading
to failure.
252 samples showed a flashpoint below ASTM specification, but this has no direct
impact to the HPFPs durability and may just be seen as an indicator for possible
gasoline content.
So 7% had wear scar over 520 but less than the max (570) allowed by the HPFP Manufacturer and of on 2.6% had wear scar which exceeded manufacturer specs.

Not seeing a lubricity issue with regards to these VW HPFP failures.

The Fuel Injection Manufacturer are just playing CYA. Their statement is purposely vague.
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Old 05-20-2013, 12:12 PM
d geek d geek is offline
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Quote:
Originally Posted by TDIwyse View Post
...Just because the particular fuel in the tank at the time the car had a HPFP failure may have had acceptable lubricity tells us nothing about the fuel that was used in it previously. It's a long term, statistical failure cause, and relying on what's in the tank at the moment as a basis to conclude what it had in there previously is, well, poor failure analysis...
I concur, and agree with ensuring the fuel has adequate lubricity (<460 micron wear scar), but until VW provides actual data on failed components we are still in the dark as to how these failures are occurring.
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Old 05-20-2013, 12:52 PM
TDIwyse TDIwyse is offline
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Quote:
Originally Posted by BMWTurboDzl View Post
So 7% had wear scar over 520 but less than the max (570) allowed by the HPFP Manufacturer and of on 2.6% had wear scar which exceeded manufacturer specs.

Not seeing a lubricity issue with regards to these VW HPFP failures.

The Fuel Injection Manufacturer are just playing CYA. Their statement is purposely vague.
203/827 = 24.5% fuel samples out of spec for viscosity, which will shorten HPFP life.
59/827 = 7.1% fuel samples out of US minimum spec for lubricity, which will shorten HPFP life. (The 570 level is where dramatic decrease in life happens, not what is "allowed by the HPFP Manufacturer". Even 520 shortens the life of the HPFP over the manufacturer's recommended 460 level)

The measured data on HPFP life has been measured by Bosch for their HPFP's. Lifespan is dramatically lowered by out of spec fuel. This is hardly a CYA. Their measured data on lifespan is not vague. It is quantifiable, measurable and reproducible.
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Old 05-20-2013, 12:55 PM
TDIwyse TDIwyse is offline
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Originally Posted by d geek View Post
I concur, and agree with ensuring the fuel has adequate lubricity (<460 micron wear scar), but until VW provides actual data on failed components we are still in the dark as to how these failures are occurring.
I agree, there seems to be more than lubricity involved with VW's issue. This is demonstrated by the multiple revisions of that pump.

My point was that lubricity is a known, measurable failure mechanism for HPFP's, and the US petro diesel spec is higher than recommended by those manufacturers.
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Old 05-20-2013, 01:06 PM
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finnbmw finnbmw is offline
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Interesting discussion. Question to the experts: What should we do to keep our BMW's running a long time without HPFP/injector problems?

Additives? BMW does not recommend using any.
Biodiesel? BMW only approves up to 5%

Seems like we are in a Catch-22 situation and at the mercy of the fuel suppliers. I've been using 95%+ Chevron fuel as I read somewhere that their diesel is among the best. Who knows? Remember that here in Southeast, we do not have premium diesel (at least haven't seen any), so probably the cetane numbers even from Top Tier stations are closer to 40 than 50.
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Old 05-20-2013, 02:59 PM
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What agency(ies) monitor the quality of biodiesel? Is it done at the state level? I know in MD the state licenses and registers gas stations and pumps but who checks the quality of the fuel itself. I think much of it comes from out of state and is trucked in from storage depots in VA and PA.
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Old 05-20-2013, 04:38 PM
d geek d geek is offline
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What agency(ies) monitor the quality of biodiesel? Is it done at the state level? ...
fuel quality is monitored and enforced at the state level
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Old 05-20-2013, 04:41 PM
d geek d geek is offline
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Who here is concerned that the HPFP used in the 328d is the same Bosch design used in the VW common rail engines?
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Old 05-20-2013, 06:03 PM
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During my diesel ownership I noted that many of the diesel pumps did not have the brand name of the fuel on them. At Exxon stations it was usually at a different location and was unbranded. I asked about it and the attendant says that most of the diesel sold in my area all came from the same place. True?
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Old 05-20-2013, 06:08 PM
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there are exceptions but generally this is true to the extent that one distribution terminal serves many retailers. The additives are mixed in when the truck is filled at the terminal. That's where the main difference lies.
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Old 05-21-2013, 03:32 AM
Pierre Louis Pierre Louis is offline
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Quote:
Originally Posted by TDIwyse View Post
I'm sorry, but that's just not backed up by the science.

http://www.arb.ca.gov/fuels/gasoline...22003bosch.pdf

Page 12 shows a quantifiable analysis on life expectancy of the HPFP vs lubricity. Lower lubricity quantifiably, measurably and verifiably reduces the life of the pump. To say otherwise is simply ignoring reality. And there's a dramatic and sharp reduction in life above 450um. One tank of really low lubricity fuel can significantly impact the lifespan.




Just because the particular fuel in the tank at the time the car had a HPFP failure may have had acceptable lubricity tells us nothing about the fuel that was used in it previously. It's a long term, statistical failure cause, and relying on what's in the tank at the moment as a basis to conclude what it had in there previously is, well, poor failure analysis. That would be like concluding that an obese man who has a heart attack while exercising with a stomach full of a salad had been practicing good dietary and exercise habits for the preceding years of his life (when he could have been a smoking, over eating coach potato).
Yes, the so-called "science" uses US diesel fuel data from 2002 before the ULSD standard came in which by itself was a large improvement in fuel lubricity and uniformity. It doesn't explain why only one pump model has most of the problems and why there are inconsistent reports of fuel lubricity relating to fuel pump "failures."

Most of the lubricity argument goes by what Bosch presented before ASTM standards were changed and the "rub" is the difference in lubricity number, something that has not been adequately shown to make a difference in the real world where fuel quality may actually be better. Its not that any critical scientific analysis wouldn't go by what they say to some extent, its that field experience needs to mirror lab data before we can jump to conclusions that don't really explain what is really happening.

The obese thing is a great example, since for years researchers believed obesity leads to heart disease but couldn't find any proof at all and still can't unlink obesity from the real risk factors of diabetes, hypertension, high cholesterol, sedentary lifestyle etc where obesity is only an aggravating factor, not a major one.

There is so much bias in all research that once we believe something, we look for it no matter what. It also explains why so many people still take Vitamin C for colds when basically all the studies show no effect except one or two where it was trivial.

PL
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Old 05-21-2013, 03:36 AM
Pierre Louis Pierre Louis is offline
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Originally Posted by d geek View Post
there are exceptions but generally this is true to the extent that one distribution terminal serves many retailers. The additives are mixed in when the truck is filled at the terminal. That's where the main difference lies.
In other words, you get the additives that the brand name, say Chevron/Texaco, has. Unbranded fuel is likely to have unbranded (read: inferior) additive.

Apparently not every brand name station has branded diesel, however, so its a bit tricky.

PL
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Old 05-21-2013, 04:57 AM
TDIwyse TDIwyse is offline
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Originally Posted by Pierre Louis View Post
In other words, you get the additives that the brand name, say Chevron/Texaco, has. Unbranded fuel is likely to have unbranded (read: inferior) additive.

Apparently not every brand name station has branded diesel, however, so its a bit tricky.

PL
This assumes they remember to put the additive package into the truck after its loaded at the terminal...
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Old 05-21-2013, 05:19 AM
TDIwyse TDIwyse is offline
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Quote:
Originally Posted by Pierre Louis View Post
Yes, the so-called "science" uses US diesel fuel data from 2002 before the ULSD standard came in which by itself was a large improvement in fuel lubricity and uniformity.
The study shows a clear connection with the variable they controlled: Lubricity. That's how a scientific study works, you control variables and test the theory you have and look to see if the measured data fit the theory. Lubricity has a direct, measurable impact to fuel pump life.

There's nothing magic about the differences of LSD instead of ULSD. The main spec difference is sulfur... Are you saying if Bosch used ULSD vs LSD in the lubricity study there would be a different result?

And I would have to take exception to the claim that ULSD standard has had a "large improvement in fuel lubricity and uniformity". VW's data sampling of fuel outlets shows horrible uniformity with large percentages of fuel being out of spec...

Quote:
Originally Posted by Pierre Louis View Post
It doesn't explain why only one pump model has most of the problems and why there are inconsistent reports of fuel lubricity relating to fuel pump "failures."
I agree the pump by itself has had some issues and its design increases loading on a smaller surface area ... This is one reason I stayed away from the VW and went with the 335d, as it uses the older, more robust HPFP.

Quote:
Originally Posted by Pierre Louis View Post
Most of the lubricity argument goes by what Bosch presented before ASTM standards were changed and the "rub" is the difference in lubricity number, something that has not been adequately shown to make a difference in the real world where fuel quality may actually be better. Its not that any critical scientific analysis wouldn't go by what they say to some extent, its that field experience needs to mirror lab data before we can jump to conclusions that don't really explain what is really happening.
The real world sampling of ULSD fuel in the US shows an alarming number of out of spec fuel that has direct, measurable impact to HPFP life (viscosity and lubricity as well as gas/water contamination).

Also, there is some good real world correlation that shows issues a connection with lubricity. Some great insight in this section of the massive TDIclub thread on the VW issues:

http://forums.tdiclub.com/showpost.p...postcount=4682

Not the increased failure rates occuring during the end of the warmer months. Warm fuel has less viscosity and lower lubricity with increases wear on the pumps ... and increased failures rates occur.

Also note that the statistical slant to the higher percentage of failures occuring in southern states where fuel temps would be hotter.

http://pics.tdiclub.com/showphoto.ph...state&cat=5765


Quote:
Originally Posted by Pierre Louis View Post
The obese thing is a great example, since for years researchers believed obesity leads to heart disease but couldn't find any proof at all and still can't unlink obesity from the real risk factors of diabetes, hypertension, high cholesterol, sedentary lifestyle etc where obesity is only an aggravating factor, not a major one.

There is so much bias in all research that once we believe something, we look for it no matter what. It also explains why so many people still take Vitamin C for colds when basically all the studies show no effect except one or two where it was trivial.

PL
Don't forget the smoking in the risk factors :-) You can be overweight and healthy, I never said you couldn't.

But we are drifting way off topic here. The original discussion was regarding fuel (biodiesel above 5%) outside of the spec that some car manufacturers were designing too. I was pointing out that even petro diesel has problems, because the data proves an alarming number of petro diesel pumps using ULSD are also outside of the spec the manufacturers designed too.

There's pros and cons to all fuel you put in your car.
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Old 05-21-2013, 05:52 AM
BMWTurboDzl BMWTurboDzl is offline
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Originally Posted by TDIwyse View Post
I agree, there seems to be more than lubricity involved with VW's issue. This is demonstrated by the multiple revisions of that pump.

My point was that lubricity is a known, measurable failure mechanism for HPFP's, and the US petro diesel spec is higher than recommended by those manufacturers.
My only gripe with the FIE statement is that they don't quantify what "Shortened lifespan" means. Does mean failure at 150k miles instead of 200k or 100k miles instead of 250k?

Is their statement simply an excuse for being unwilling to meet certain service life requirements? It's not like the lubricity requirement changed when we transitioned to ULSD.

Who knows.
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Old 05-21-2013, 05:53 AM
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Originally Posted by d geek View Post
there are exceptions but generally this is true to the extent that one distribution terminal serves many retailers. The additives are mixed in when the truck is filled at the terminal. That's where the main difference lies.
This is definately true for gasoline, it is the additive that makes it a brand. But thought for diesel there were no branding additives, it is pumped as it came from the refinery?

Last edited by KeithS; 05-21-2013 at 06:23 AM.
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  #23  
Old 05-21-2013, 06:11 AM
BMWTurboDzl BMWTurboDzl is offline
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Quote:
Originally Posted by KeithS View Post
This is definately true for gasoline, it is the additive that makes is a brand. But thought for diesel there were no branding additives, it is pumped as it came from the refinery?
Lubrizol is a big supplier of fuel additives. They even supply retail "Aftermarket", but won't tell you who.
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Old 05-21-2013, 07:14 AM
TDIwyse TDIwyse is offline
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Originally Posted by BMWTurboDzl View Post
My only gripe with the FIE statement is that they don't quantify what "Shortened lifespan" means. Does mean failure at 150k miles instead of 200k or 100k miles instead of 250k?

Is their statement simply an excuse for being unwilling to meet certain service life requirements? It's not like the lubricity requirement changed when we transitioned to ULSD.

Who knows.
Well, it seems to me the Bosch study does quantify it. For example, page 11 has a table showing the wear scar ratings and durability reduction. At the higher end you get only 1% of the expected life and near "immediate failure". It also quantifies the failures that occurr with the different type of fuel pump designs along with photographs of what the failures look like. The "fretting" (http://en.wikipedia.org/wiki/Fretting) that occurs from lack of lubricity is the type of thing that would result in the metal particles that get strewn about the fuel system in those TDI failures.

Also, here's the official ASTM specs on diesel:

http://enterprise2.astm.org/DOWNLOAD/D975.101932-1.pdf

The only difference in spec for LSD vs ULSD that I can see is the sulphur rating.

However, the process for removing sulphur also strips some of the inherent lubricity from the fuel. Untreated LSD has inherent lubricity HFRR in the 390-500 range, where as ULSD is significantly higher at 600-800.

http://www.wellworthproducts.com/art...tionsulfur.asp

If the load of ULSD misses its additive package then that load of fuel will have way out of spec lubricity.
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Old 05-21-2013, 07:19 AM
Pierre Louis Pierre Louis is offline
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Originally Posted by TDIwyse View Post
The study shows a clear connection with the variable they controlled: Lubricity. That's how a scientific study works, you control variables and test the theory you have and look to see if the measured data fit the theory. Lubricity has a direct, measurable impact to fuel pump life.

There's nothing magic about the differences of LSD instead of ULSD. The main spec difference is sulfur... Are you saying if Bosch used ULSD vs LSD in the lubricity study there would be a different result?

And I would have to take exception to the claim that ULSD standard has had a "large improvement in fuel lubricity and uniformity". VW's data sampling of fuel outlets shows horrible uniformity with large percentages of fuel being out of spec...



I agree the pump by itself has had some issues and its design increases loading on a smaller surface area ... This is one reason I stayed away from the VW and went with the 335d, as it uses the older, more robust HPFP.



The real world sampling of ULSD fuel in the US shows an alarming number of out of spec fuel that has direct, measurable impact to HPFP life (viscosity and lubricity as well as gas/water contamination).

Also, there is some good real world correlation that shows issues a connection with lubricity. Some great insight in this section of the massive TDIclub thread on the VW issues:

http://forums.tdiclub.com/showpost.p...postcount=4682

Not the increased failure rates occuring during the end of the warmer months. Warm fuel has less viscosity and lower lubricity with increases wear on the pumps ... and increased failures rates occur.

Also note that the statistical slant to the higher percentage of failures occuring in southern states where fuel temps would be hotter.

http://pics.tdiclub.com/showphoto.ph...state&cat=5765




Don't forget the smoking in the risk factors :-) You can be overweight and healthy, I never said you couldn't.

But we are drifting way off topic here. The original discussion was regarding fuel (biodiesel above 5%) outside of the spec that some car manufacturers were designing too. I was pointing out that even petro diesel has problems, because the data proves an alarming number of petro diesel pumps using ULSD are also outside of the spec the manufacturers designed too.

There's pros and cons to all fuel you put in your car.
Reading the actual ASTM decision on lubricity will tell you ULSD is much more uniform and has overall improvements in many aspects including lubricity over prior LSD.

Lab data is great and it is scientific, but science is about reality and theories to be believed must also be proven in the field. This is not so simple and has been an issue in many forums.

The information here is difficult to come by for many reasons. I am unaware of any statistics about total usage or incidence of problems etc. We don't know about how many fuel pumps go on without problems and for how many miles, for example. There is no "real world sampling of ULSD" data that is of any use either, probably due to real world variables not reproducible in the lab. You won't find proprietary data from aftermarket additive manufacturers using consumer fuel samples, for example, to support their claims published anywhere.

I enjoy the reasonable responses of most posters in the BMW world and have no axe to grind for or against any "theory" but lets not make believe there is science where it is not.

PL
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