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Biodiesel cars

It is common for people to ask if there is a special biodiesel car. The short answer is that no manufacturer produces a special biodiesel vehicle.

Most manufacturers do warrant their vehicles on a blend of biodiesel. In certain European countries some manufacturers allow B100 to be run without effecting the warranty.

Volkswagen's vehicle manuals will specify if the vehicle will run on RME (Rapeseed Methyl ester - Biodiesel). These types of vehicles can be classified as manufacturer warranted biodiesel cars and a number of people consider their VW engines to be biodiesel Tdi's. Certainly the Tdi engine seems to be quite happy running biodiesel.


Biodiesel tdi


What are the biggest problems that cars running biodiesel have?

  • It cleans out your fuel system

    Normal diesel can be foul stuff. Over a period of time it will leave sludge in your fuel system and will even varnish the inside of your fuel tank and pipes. Using any blend of biodiesel will dissolve this rubbish in your tank and move it through the fuel system. This typically causes the fuel filter to block up.

    The treatment is to change the fuel filter when it begins to block and to keep a spare one with you during the first few thousand miles on green fuel. Symptoms of the fuel filter blocking are rough running, missing in the engine, excessive smoke and loss of power. This is one of the most common disadvantages of biodiesel, but thankfully it is not serious and goes away as soon as the fuel system is flushed.

  • Material Incompatibility

    Older vehicles used natural, Buta-N or nitrile rubber components in the fuel pump and in the fuel lines. These rubbers are biodiesel incompatible and will soften, harden or dissolve. As a general rule - any vehicle made prior to 1994 may have a problem with biodiesel but vehicles made after this should be fine. It is important to check your vehicles manual to see if the manufacturer specifies you can use biodiesel. If so, at what percentage. Failure to do so will invalidate your vehicle warranty and might lead to expensive repairs to your fuel system.

    If you want to use biodiesel in older vehicles you may have to replace these components with compatible ones. There are biodiesel conversion kits on the market for certain vehicles that will allow you to do this. If you are replacing the seals and hozes use Viton parts where possible as these are safe to use with biodiesel.

The only other biodiesel conversion is to heat the fuel lines - this is discussed in cold weather problems.

Modern vehicles which are designed to use ultra low sulfur diesel all have fuel systems that should work just fine but bear in mind the warranty issues.

Most modern manufacturers will warrant a vehicle for a 5 or 10% blend (B5 or B10). Some manufacturers like Citroen will warrant their vehicle for a 30% blend. Companies like Cat will warrant their engines for a 20% blend.

Biodiesel Colt Rodeo

It is critical for fuel injection and engine manufacturers that their vehicles will run properly on a given type of fuel. When it comes to alternative fuels this is very difficult to guarantee and the biggest reason for this is a lack of quality guaranteed fuel. For example Citroen warranted their vehicles on B30 only when one of the large French refineries produced a B30 blend for the Pumps. Citroen was then able to certify their vehicles on quality guaranteed fuel.

There are plenty of people running B100 blends successfully. Just because the vehicle manufacturer does not warrant the vehicle does not mean it is not compatible.


So nearly all biodiesel cars are just ordinary cars that run biodiesel. Manufacturers that will warrant their vehicle on biodiesel are few and far between.



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