Well, as for proving I use BioD, there is always the fact my car is plastered with a bunch of "Powered by Biodiesel" and the like stickers ;-)

Alright heres the deal, if you have an engine problem, the manufacturer is going to do everything in their power to proove that the problem was related to something other than manufacture defect. Anyone who has ever had to argue a warrantty issue with a dealership will understand this.

To do this they will first need to figure out what caused the engine failure, this means lab test. All the fluids to included engine fuel are drawn off and tested. Newer computerized diesels will have the engine performance logs downloaded from the ECU.

Heres the deal if your engine dies with biodiesel in it, it will be in the fuel lines, fuel filters, injector pump all the way up to the injector nozzles. It would be a task to bleed all of the biodiesel out of the system. Trust me I've lost prime in my vintage Mercedes before, nothing says love for diesels like spending time pumping on a little knob in a cramped space while bleeding the air out of the injector in the cold.

The way the warranties are written currently. So long as the fuel in the engine meets the manufacturers specifications, the cause of the failure cannot be blamed on fuel (you). The achilles heel here is that out of spec fuel has never been a liability for manufactures. Now exact warranty law is different state to state, but essentially if the fuel in the engine is within ASTM spec (the manufacturer cannot write a specification higher than the current fuel standard) you should not suffer collateral engine damage.

AFAIK there has been no warranty litigation with any engine manufacturer over the use of biodiesel. The major concern for spec. bio-diesel is not the fuel itself, its fuel contamination. Biodiesel without preservatives or biocides has a shelf life of 6 months in ideal conditions. In a B20 mix save for preexsisting tank contamination or petrol contamination the shelf life is slightly higher.

Another concern is the hygroscopic nature of the fuel. Meaning that it absorbs moisture in the air. Also it can attack certain metals, like cast iron, zinc, maganese, copper based alloys, cobalt, lead and tin.

And of course we all know about the viscosity problems of B100 in cold climates.

Currently Daimler Chrysler will be shipping all american made diesels with a factory mix of B5 and currently the warranty covers that. Commercial grade spec fuel upto B5. Daimler Chrylser is warrantying all Dodge Ram/Utility, Military and specified fuel fleets for B20.


By 2010 ULSD will be mandatory for non-road diesels. Emissions profiles will vary by engine and displacement, but full compliance of grandfathered vehicles is expected by 2030. This is particularly important for non-road diesels as they have long lifetimes


I have been pretty upset about this warranty issue for a few years now. But it seems I am upset over a theoretical situation. The big thing in the biodiesel industry is quality assurance. The National Biodiesel Accreditation Commission (NBAC) was formed to perform spot checks on suppliers and marketers. Passing means your are an accredited supplier.


So it looks like the popular sentiment right now is B20. Hopefully this will be raised, what this means is that engine manufacturers have never warrantied problems related to fuel or fuel system components, it also goes on to mean that any engine performance problems encountered by use of the fuel will not be considered.

Cummins does not approve or dissaprove the use of bio-diesel. Instead they refer to a statement from Bosch "Bosch states in their Diesel Fuel Quality -- Common Position Paper (03/05/99) that no guarantee on FIE is given so far to any alternative fuel except for Diesel + 5% FAME. There is a major difference between operating on pure (100% concentration) biodiesel fuels and biodiesel/petro
diesel fuel blends."

Detroit Diesel recommends a 5% blend maximum, and the resulting mix must meet the ASTM standard for diesel.

Ford reccomends a 5% blend maximum, it also states that it does not believe that bio-diesel alone will be clean enough to satisfy Tier 2 specs.

GM reccomends a 5% blend maximum for fleets as long as the fuel meets ASTM standards for biodiesel.

International reccomends a 5% blend maximum, they do not void the warranty, but will not repair problems under warranty for blends higher than 5%.

Currently John Deere is shipping all of its tractors with a factory blend of B5. Strongly advises against SVO specifically. Use of biodiesel does not void warranty, only repairs due to specific damage.

VW reccomends a 5% blend maximum, they do not void the warranty, but will not repair problems under warranty for blends higher than 5%. They also stipulate that they will not cover damage for substandard diesel fuel.

Volvo reccomends a 5% blend maximum, warranty good only for blends upto B5. Reccomends halving oil change schedule due to "dilution". Has no intention of testing engine for higher blends, stating that the ASTM standard is not enough. Volvo also cites "potential" injector pump damage for blends higher than B5.


Alright looking at this further, these engine manufactures have aligned themselves with the Engine Manufacturers Association (EMA). The EMA has aligned themselves with the Fuel Injection Equipment (FIE) manufacturers. FIE feels that the following problems are attributed to high concentrations of renewable fuels and thus are the reason to not use them above B5:
Fuel system seal failures
Particulate filter clogging prior to injector pump
Fuel injector blockage, resulting in poor atomization.
Dilution and polymerization of engine oil
Injector pump failures due to poor viscosity oil in cold climates.
Increased injection pressure.
Corrosion of fuel system components.
Poor long term storage ability of biofuel.

FIE is not willing to reccomend a higher than B5 concentration without the inclusion of the following specifications in an international standard:

Exclusion of SVO
High concentrations of methanol in fuel.
NaOH or KOH particles in the fuel.
Water content
Glycerine content
Free fatty acids
High viscosity at low tempartures
Maximum fuel shelf life (Orgainic Acids, Oxidation)
Iodine Value
Total Acid Numer

After reading this I can understand the logic to the concerns, however I am slightly appalled. According to the National Biodiesel Board in 1998, 50% of the diesel fuel tested did not meet minimum lubricity standards.

I agree that standards need to be established, and for fuel that is going to store for a few months I could even agree that additive packages for fuel stability and anti-microbials be added. But I dont understand how they could hold this fuel to standards when there is so much substandard petrol diesel on the market. These component failures where happening at an accelerated rate for years and years and nobody said anything because if your a manufacturer whats the best way to stay in business.

I strongly suspect that FIE has some alliances with the petrol oil industry. In any case although their have been 43 million miles driven by folks with B20 blends or higher, there is a engineering change to comply with the new ULSD standards. There is now no empirical data to support this new equipment and how concentrations higher than B5 will react with the cataylytic converters and particulate traps.

Of all the manufacturers only VW is committed to raising the bar to B20 after some more extensive testing. Ultimatly this will lead to changes in the injection system that are directly suited for biodiesel.