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Fuels & Lubricants Discussion all about Fuels & Lubricants. synthetic oil, conventional oil, brands, change intervals, diesel grades, gelling and such debated items like that. Non TDI related postings will be moved or removed. This forum is NOT for the discussion of biodiesel and other alternative fuels.

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Old November 20th, 2007, 15:54   #1
tditom
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Default fuel lubricity data- with and without additives.

I have been concerned about diesel fuel lubricity, especially with ULSD coming on the scene.

As you know, the high pressures inside our fuel injection systems require very close tolerances between the pump components. The only lubrication these components receive is from the diesel fuel. The process of lowering the sulfur content also lowers the lubricating properties of the fuel. When the implementation plan of ULSD was being developed here (the U.S.), a push was made for a lubricity standard for US diesel fuel.

The test for fuel lubricity is performed on a High Frequency Reciprocating Rig (HFRR). Here is a description of the test (LINK -you will need to search on hfrr):
Quote:
...The instrument uses an electromagnetic drive to oscillate an upper 6 mm diameter steel ball bearing against a stationary lower steel test plate. The reciprocation frequency and stroke length are controlled to 50 Hz and 1 mm respectively throughout the 75 minute test. The contact is fully immersed in the test fuel which is maintained at 60°C. The ball is loaded against the plate by means of a suspended 200 gm weight. All test parameters are controlled automatically through a PC via a custom electronic interface. The friction coefficient, electrical contact resistance and temperature are displayed in
graphical format as the test proceeds and the test data are saved to file. The performance of the fuel is assessed by measuring the diameter of the wear scar formed on the ball using a 1 micron resolution microscope. The test result is sensitive to the moisture content of the atmosphere, consequently an adjustment is made depending on the ambient conditions or the atmosphere is controlled e.g. by enclosing the instrument in a humidity controlled cabinet...
The maximum wear scar acceptable in Europe and Canada is 460 microns.

Here is a presentation from Bosch in 2003 that detailed the issue of lubricity, and gave an assessment of US fuel supply at that time. Remember that this was before ULSD was on the scene. They were pushing for a fuel lubricity standard to be implemented for LSD, which has more "natural" lubricity than ULSD. Note on slide 8 that 80% of US fuel stations tested had a wear scar >460 microns. Take a look at the photos of FI components that were run with fuels that had varying lubricity properties.

Here is a summary of ASTM's process for arriving at 520 micron max wear scar.
Quote:
Originally Posted by excerpt
...Revision of D 975-02 Specification for Diesel Fuel Oils to include a lubricity specification

PLEASE READ THIS NOTE AND THE SUPPORTING DOCUMENTS BEFORE VOTING.
...¸ Most members believe that we need to adopt a lubricity specification at ASTM to protect injection equipment from excessive wear.
...¸ The CRC Diesel Performance Group has committed to conduct a research program to provide additional supporting data to adjust this level if necessary, especially for the new high-pressure common-rail injection equipment.

Data and Discussion Supporting the Proposal: One technical supporting document for the proposed level is an SAE Technical Paper 2001-01-1928. An interpretation of the data in Table 5 by Ken Mitchell results in an average scar diameter of 517 microns for a passing pump rating of 3.4.

Since the lubricity correlation is not an exact science at this time, we also can find documents that conclude HFRR at 550 or HFRR at 500 microns. The proposed level of 520 microns based on the above document is a reasonable technical compromise to ensure proper protection for injection equipment.

It is worth noting that, although the correlation between SLBOCLE and HFRR is not close to perfect, most supporting documents and field data indicate that the proposed 520 micron HFRR level does not result in lower lubricity when compared to our previous proposal of 3,100 gram SLBOCLE level. In many cases it should provide better fuel lubricity.
...

Steps Beyond the current Proposal: This proposed specification will provide a starting point that would protect the injection equipment without creating harmful side effects and unnecessary cost to the fuel suppliers. ...
No rationale was given for not adhering to the FI manufacturers' recommendation. The bolded statement at the end of the excerpt indicates what the influence was.

I was able to contact one of the author's of the Bosch presentation, and he was actually on the ASTM committee that set the 520 standard. He could not explain why he agreed to the more lenient spec when his presentation clearly had 460 as a MAX allowable wear, and <400 preferred. My conclusion is that the other ASTM members wore him down and convinced him that the fuel distributors would sufficiently protect the FI equipment. He also told me that he was more concerned with people over-doing it with additives, and causing more potential problems than benefits. For this reason he advised against using additives. He verified that additives for lubricity must be added to ULSD to bring it to spec, and that those additives are applied at the fuel terminal, when the fuel goes into a tanker truck.

I have been using biodiesel mixtures for a long time, partly based on the lubricity tests done using various concentrations of biodiesel. Here is a paper on that. The takeaway is any biodiesel concentration above 2% will adequately protect your fuel injection components with D2 that meets the ASTM standard for lubricity. Note that VW (and most other diesel mfrs) recommend that you limit biodiesel to 5%.

In a recent thread discussing additives, I was noting that I could find very little data from additive manufacturers. I contacted Power Service and asked for some data. A few days later I got it in the mail. I was unsure if I was seeing retail pump fuel or not. So I called PS and talked to the guy who sent me this data. He verified that this was in fact untreated fuel, so that was somewhat of a relief. (Ironically, this was the same test method used by Spicer in his test.)

The following data sheet is for raw (fuel that has no additives applied at the terminal) LSD:
[IMG][/IMG]
It should be noted that the HFRR results were way over spec before PS Diesel Fuel Service "DFS" (white bottle) or Diesel Kleen "DK" (silver bottle) was added. This gives us an idea of what kind of fuel our vehicles could have seen before 2005!!

The following results were for raw ULSD:
[IMG][/IMG]
Note that the HFRR result for this untreated fuel was actually better than LSD. See the resultant HFRR results after treatment with DFS.

Next, see a horrendous example of raw ULSD (for an idea of how important lubricity additives are with this fuel). Again note the benefits from DFS:
[IMG][/IMG]


During this conversation he told me that because of testing repeatability and variability, the passing mark for HFRR was actually 560! So now we're talking about fuel being ~22% worse than the MAXIMUM wear results allowed by the people who manufacture our FI equipment!!

I asked the guy at PS to send retail pump fuel data, so we could see what PS products do in the real world. He emailed me a couple of results from retail pump fuels. He explained that the data was generated for a fuel that was subsequently cut with biodiesel, but assured me that the HFRR results were taken before biodiesel was added, so the lubricity improvement shown was strictly from PS products over retail fuel that had already been additized at the fuel delivery terminal.
First results:
[IMG][/IMG]
So here we have lubricity that is just a bit above the allowable limit coming out of the pump. Note the improvement shown using DFS.

Here is the last data sheet:
[IMG][/IMG]
These results show a fuel out of the pump that barely meets the standard, and that it was brought down 130 microns by DFS.

Besides FPPF, this is the only additive manufacturer data that I can find real numbers on. If you have links to other data, please post them on this thread.

Here is "data" from FPPF:



OK, so what all of this tells me we should use some sort of fuel lubricity additive, being careful to stick to the recommended dosing. I would recommend an additive that actually provides data. The only ones I know of at this point are biodiesel, Power Service (both white and silver) and FPPF. I do NOT trust the fuel supply system in this country to take care of this for me. If anyone has a link, or data for another additive manufacturer, please add them here. Thanks.
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autos: 15 Volvo V60, 08 MB E320 Bluetec
Find your VW part numbers here.
Why I recommend fuel additive.

Last edited by tditom; December 5th, 2012 at 08:11. Reason: fixing broken link
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Old November 20th, 2007, 16:07   #2
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Having purchased fuel in 10 states in the last month I not so confident in fuel standards from one part of the US to the other . I dose with BD & power service every tank and have for years .

I did find out that LOVEs truckstops sell B5 at every station across the US .
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Old November 20th, 2007, 16:36   #3
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I guess I am not worried. We have had it for long enough now that we should be seeing the beginnings of problems if there were any, and we are not seeing them.

ULSD has been available in more advanced countries around the world for some time and, well there have not been all the terrible things happening that some have forecast.
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Old November 20th, 2007, 16:42   #4
tditom
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Quote:
Originally Posted by Joe_Meehan
...
ULSD has been available in more advanced countries around the world for some time and, well there have not been all the terrible things happening that some have forecast.
Those "more advanced" countries (like Canada ) have a tighter lubricity standard, and AFAIK it is better enforced.

I'm not against ULSD at all. I just don't think lubricity is being adequately addressed/enforced.
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Old November 20th, 2007, 16:58   #5
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This is ridiculous and disturbing. I've been concerned for a long time whether the fuel distributors are actually taking the care required to deliver a quality product. It's obvious they're not.

T, just how much does it cost to have fuel tested at this level?

The pump rebuild people will be rubbing their hands together in evil delight after reviewing this data.
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Old November 20th, 2007, 17:07   #6
tditom
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dd- no idea how much it costs. I will ask my contact at PS. George M. should have a connection for this sort of info.
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Old November 20th, 2007, 17:21   #7
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Noticed that they didn't test DK except for the first test. You can make the assumption that DK will always be better than DFS, but we really do not understand the potential chemical reaction that may take place between PS's lubricity additive and an oil company's unless they actually run the test. It may actually lower it. Just don't know...

I use DK exclusively because of the warmer climate where I live.
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Old November 20th, 2007, 17:23   #8
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"I did find out that LOVEs truckstops sell B5 at every station across the US ."

That's incorrect. I just called our local store which is less then a year old and they do not sell biodiesel. Some do, some don't.
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Old November 20th, 2007, 17:29   #9
tditom
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Quote:
Originally Posted by tollerTDI
Noticed that they didn't test DK except for the first test.
Yeah, the tests were all done on winterized fuel, so DFS would be more appropriate.

You can make the assumption that DK will always be better than DFS
I don't see how you can make the assumption that DK is always better?
, but we really do not understand the potential chemical reaction that may take place between PS's lubricity additive and an oil company's unless they actually run the test. It may actually lower it. Just don't know...
The last two charts are for fuels that did have oil co. additives, so we do have an indication that the PS effect does make a further improvement, right?

BTW, PS does make additives for the oil companies too.
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Old November 20th, 2007, 17:52   #10
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Ok. Looks like in terms of lubricity, DK and DFS should be the same. I just thought I read somewhere that DFS being designed for Winterizing had less, but I'm probably mistaken.
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Old November 20th, 2007, 17:52   #11
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Quote:
Originally Posted by dieseldorf
This is ridiculous and disturbing. I've been concerned for a long time whether the fuel distributors are actually taking the care required to deliver a quality product. It's obvious they're not.

T, just how much does it cost to have fuel tested at this level?

The pump rebuild people will be rubbing their hands together in evil delight after reviewing this data.
I know its not enough according to this one sample, but I would hardly call it "data."

Do we know on what basis the wear scar recommendation was made?

We really don't know enough to make conclusions. Just have to trust the pump manufacturers for their number recommendations. Thats all we really have, no?

TM
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Old November 20th, 2007, 18:05   #12
tditom
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Quote:
Originally Posted by Tin Man
...We really don't know enough to make conclusions. Just have to trust the pump manufacturers for their number recommendations. Thats all we really have, no?

TM
Would you rather trust the pump manufacturers' recommendations, or ASTM? Who is more likely looking out for your investment?
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Old November 20th, 2007, 18:28   #13
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Wow am I glad I live in Minnesota where all diesel is now B2 !! And I run with B20 in the summer months.
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Old November 20th, 2007, 20:49   #14
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Quote:
Originally Posted by tditom
Would you rather trust the pump manufacturers' recommendations, or ASTM? Who is more likely looking out for your investment?
Good question. I really don't know to be honest with you.

The pump manufacturers can be setting a high standard and if a pump goes awry, they can say "see I told you so." It is in their best interest to set the bar high.

Technically, ASTM should have the public's "general" interest in mind, i.e. make the best reasonable compromise. I don't know if they represent anyone's interests, but I know that if they set a standard that everyone tries to do better than (so as not to get fined by the government inspectors), they may be doing just that.

The legal and regulatory world is a strange thing when it comes to truth and behavior.

And how about the endpoint: longevity. Is it up to the pump manufacturers to make a pump with good enough metallurgy and materials that will last longer than the rest of the car? Will additives make any difference overall? Can the manufacturers be able to provide us with better pump life without the cost of additives? Will using the lubricity improver make a fuel pump, on average, go for 160,000 miles vs. 130,000 miles, or will it be extended to 450,000 miles instead of 400,000 miles? The first miles quoted would be worth the trouble of using additives, the second set not. How do we know if the ASTM number differs enough from the pump manufacturers number to be significant? This is just basic statistics and how peer review is done on any decent research.

And again, why are we not supplied with the pertinent information? Why are we left guessing? Why can't they just tell us that using additive X will prolong your pump's average lifespan by Y and we have the data to prove it, and here it is...

But I would be the first in line to use an aftermarket additive if I had this information and it did matter. I was one of the first to use Mobil 1 when it came on the market, and they did show us data including its molecular structure etc. I could tell the difference in fuel additives from different manufacturers early on. I had friends in the oil company additive business explain a lot of things to me.

I refuse to believe that pump manufacturers are so dependent on the variables of additive lubricity as to make it a holy grail for us to put them in after fuel suppliers carefully tailor their own additives.

So, honestly, I don't know.

TM
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Old November 20th, 2007, 20:52   #15
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Quote:
Originally Posted by MethylEster
Wow am I glad I live in Minnesota where all diesel is now B2 !! And I run with B20 in the summer months.
Yeah, the government should pick up the ball and require at least B2 to help in several ways, not the least of which is renewable fuel and improved lubricity.

TM
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