Service Information: Operation with fatty acid methyl ester (FAME)

 This information includes the results of the latest tests on the topic of fatty acid methyl ester (FAME) for the above-mentioned vehicles and engine model designations. The Service Information bulletin is suitable for handing over to customers.
The information in SI00.40-N-0008A continues to be valid for older vehicles and engine model designations.

Notes on operation with FAME

1. Approvals

The following vehicle/engines are approved or not approved for operation with FAME.

Preliminary remarks

Several abbreviations are common in describing biodiesel fuels.

 Fatty acid methyl ester (FAME)

Generic term used in EU standards

 Vegetable oil methyl ester (VOME)

Generic term used previously in German-speaking areas

 Rape methyl ester (RME)

Biodiesel fuel made from rape seed oil

 Used Cooking Oil Methyl Ester (UCOME)

Biodiesel fuel that is produced from waste materials such as used cooking oils and fats

2. Fuel

 The fuel must conform to DIN EN 14214. Operation with lower quality fuel can lead to damage and malfunctions. Mercedes-Benz shall not be held liable for irregularities and damage resulting from poor quality fuel.

 Operation with fuel approved by DIN EN 14214, which is overwhelmingly produced from used cooking oil or cooking fat (UCOME), is not permissible.

 FAME or diesel fuel may be used alternately. The various mixtures of FAME and standard diesel fuel occurring in the fuel tank in such cases is acceptable.

 The use of diesel fuel with a FAME additive of maximum 7 % is safe. This fuel can also be used in vehicles which are not approved for operation with FAME and it has no influence on the oil change intervals.

 As a matter of principle, we do not approve of the use of pure vegetable oils as an alternative to diesel fuel or FAME due to negative experiences (engine damage resulting from carbon deposits, deposits in combustion chambers and oil sludging).

 If the low-temperature stability is not sufficient or at lower outdoor temperatures, a fuel preheating system is required.

 At outside temperatures below 5 °C, Mercedes-Benz recommends changing from the use of fatty acid methyl ester (FAME) fuel to commercially available diesel fuel.

 European standard DIN EN 14214 requires the following low-temperature stability for FAME:

Time period Low-temperature stability down to*

 15.04. - 30.09. 0 °C

 01.10. - 15.11. -10 °C

 16.11. - 28.02. -20 °C

 01.03. - 14.04. -10 °C

3. Engine oil and maintenance

 Vehicles that are approved for operation with FAME, when operated exclusively ex-factory or after each engine maintenance with fossil diesel fuel, reach the regular oil change intervals (without any reduction due to operation with FAME). If, during the maintenance interval, the vehicle is refueled with FAME, i.e. a FAME content in the fuel tank of >  7 %, this is automatically detected by the maintenance system and the maintenance interval is reduced.

 For operation with FAME, engine oils that conform to MB Specifications for Operating Fluids, Sheet 228.51 or 228.61 are preferred. Engine oils conforming to Sheet 228.31 can also be used if the oil change intervals are also reduced.

 For vehicles with a diesel particulate filter (DPF), the replacement intervals for the DPF remain unchanged at the 3rd engine maintenance, and thereafter at every 2nd engine maintenance.

 A certain amount of fuel always gets into the engine oil through the piston and cylinder pairings. Its high boiling point prevents FAME from evaporating and therefore it remains almost completely in the engine oil. Under certain conditions, chemical reactions can occur between the FAME and engine oil.

 For this reason, the engine oil and oil filter replacement intervals are shortened both for vehicles operating solely on FAME and for vehicles with FAME-diesel mixed-fuel operation.

 The specified engine oil and fuel oil filter change intervals must be complied with at all times. Exceeding the replacement intervals can result in engine damage.

4. Engine power

 Operation with FAME instead of diesel fuel does not affect engine performance. However, the lower calorific value of the FAME fuel leads to an increase in the injection quantity, which in turn increases the level of fuel consumption in comparison to operation with diesel fuel.

5. Auxiliary heaters

Generally, all auxiliary heaters can be operated with diesel fuel or fuel oil from an additional fuel tank. This solution prevents any sticking in the stationary heater and ensures that the auxiliary heater operates properly at low outside temperatures.

6. Miscellaneous

 As a consequence of the limited durability of FAME, and to avoid any sticking, the fuel system is to be flushed with diesel fuel before any extended engine immobilization periods. To do so, fill the almost-empty fuel tank with diesel fuel and drive for at least 30 minutes or run the engine at standstill at changing speeds. FAME operation is not a good idea for vehicles which are generally idle for long periods (e.g.  fire service).

 FAME is an extremely effective solvent. Therefore any contact with paint is to be avoided. We assume no liability for paint damage resulting from contact with FAME.

 Not all manufacturers of engine oils based on rerefined products are capable of processing engine oils that exhibit ester residues from operation with FAME. Please consult your used oil dealer in this regard.

 Mercedes-Benz shall not assume any warranty for damage resulting in context with the use of poor quality FAME or failure to observe our specifications for operation with FAME. The resulting irregularities and subsequent damages are not within the range of responsibility of the manufacturer.