ERE
Silver Member
This is a topic that has as many opinions as there are owners, but I just got an education so I thought I'd share it since even off road fuel is now ULSD. I've owned a bunch of diesel cars and tractors over the years, and prior to retiring had a lot more professional experience with big diesels, but I never really tripped onto the implications to our machines that occurred when the US fuel supply shifted to Ultra low sulfur diesel. I was pulled into this because I own a common rail diesel car and since common rails run at much higher pressure than older diesel technology, they are at proportionally larger risk. There are many high pressure fuel pump failures that people attribute to poor US fuel. Here in bullet form is some of what I have learned.
- The process of making ULSD strips out almost all of the lubricity needed by pumps and injectors.
- The EPA, when they set the new standard, set the lubricity standard at 520 microns (lower is better). This is a measure of the wear scar produced on a device called a high frequency reciprocating rig, HFRR.
- Both the Engine Manufacturers Association and Bosh, one of the largest manufactures of diesel fuel injector components, say that a wear scar of 460 or less is needed to prevent premature failure of components. Some sources say 400 or lower is what is needed.
- It is difficult to impossible to determine what your local diesel fuel is. Manufactures are tight mouthed about ratings and fuel supplies vary a lot in different locations with season and changing of jobbers. About all you can depend on is that the fuel is >40 cetane and < 520 wear scar.
- Fuel additives claim a lot of things but few show any evidence of testing to the customer so we are left with trying to guess what a good additive is. Most seem to be aimed at anti gell and cetane improvement. Some say they improve lubricity but don't say by how much.
- Bio diesel is one of the best lubricity fuels there is, and a mix of 2% bio will put you well into the acceptable range.
- Bio has some drawbacks as you go to higher percentage mixes, so if you intend to use it, should understand how long it can be stored, its propensity for water, and it's propensity for diluting your engine lube oil. In general these are not issues at low percent mixes.
Ok, thats enough of that. I now use a lubricity additive in the fuel for the three diesels I currently own. I don't worry much about cetane but in the winter I do concern myself a little with gelling. Here is a web site that has actual laboratory testing results for lubricity improvement for a bunch of additives. Note this is not the original document, but a copy of it. I once found the lab report, but can't find it any more. This however appears to be a direct cut and paste. It also gives you a good guide as to how much of each additive is needed to get a given improvement. Note that some additives actually reduce lubricity.
TDIClub Forums - View Single Post - Addative Study
Here is a study by Wayne State University giving more info than I wanted to know about bio. http://www.eng.wayne.edu/user_files/414/file/Quick_Upload/Lubricity_ Kapila(1).pdf
Here is a DOE study that pretty much says that engine oil dilution in biodiesel ratios up to 20% seems to be acceptable. The dilution happens, but bio seems to have such good lubricity that it doesn't affect the lube oil properties too adversely.
http://www.nrel.gov/vehiclesandfuels/npbf/pdfs/44833.pdf
This is a long post - sorry. There is a ton of information and opinion on the web in the various Ford, VW, Cummins, etc websites. I think everyone should make up their own mind on what to do. So for what it's worth, the above is offered as a starting point to save you some time if you haven't already tripped to this problem (as I hadn't).
- The process of making ULSD strips out almost all of the lubricity needed by pumps and injectors.
- The EPA, when they set the new standard, set the lubricity standard at 520 microns (lower is better). This is a measure of the wear scar produced on a device called a high frequency reciprocating rig, HFRR.
- Both the Engine Manufacturers Association and Bosh, one of the largest manufactures of diesel fuel injector components, say that a wear scar of 460 or less is needed to prevent premature failure of components. Some sources say 400 or lower is what is needed.
- It is difficult to impossible to determine what your local diesel fuel is. Manufactures are tight mouthed about ratings and fuel supplies vary a lot in different locations with season and changing of jobbers. About all you can depend on is that the fuel is >40 cetane and < 520 wear scar.
- Fuel additives claim a lot of things but few show any evidence of testing to the customer so we are left with trying to guess what a good additive is. Most seem to be aimed at anti gell and cetane improvement. Some say they improve lubricity but don't say by how much.
- Bio diesel is one of the best lubricity fuels there is, and a mix of 2% bio will put you well into the acceptable range.
- Bio has some drawbacks as you go to higher percentage mixes, so if you intend to use it, should understand how long it can be stored, its propensity for water, and it's propensity for diluting your engine lube oil. In general these are not issues at low percent mixes.
Ok, thats enough of that. I now use a lubricity additive in the fuel for the three diesels I currently own. I don't worry much about cetane but in the winter I do concern myself a little with gelling. Here is a web site that has actual laboratory testing results for lubricity improvement for a bunch of additives. Note this is not the original document, but a copy of it. I once found the lab report, but can't find it any more. This however appears to be a direct cut and paste. It also gives you a good guide as to how much of each additive is needed to get a given improvement. Note that some additives actually reduce lubricity.
TDIClub Forums - View Single Post - Addative Study
Here is a study by Wayne State University giving more info than I wanted to know about bio. http://www.eng.wayne.edu/user_files/414/file/Quick_Upload/Lubricity_ Kapila(1).pdf
Here is a DOE study that pretty much says that engine oil dilution in biodiesel ratios up to 20% seems to be acceptable. The dilution happens, but bio seems to have such good lubricity that it doesn't affect the lube oil properties too adversely.
http://www.nrel.gov/vehiclesandfuels/npbf/pdfs/44833.pdf
This is a long post - sorry. There is a ton of information and opinion on the web in the various Ford, VW, Cummins, etc websites. I think everyone should make up their own mind on what to do. So for what it's worth, the above is offered as a starting point to save you some time if you haven't already tripped to this problem (as I hadn't).
