Service Information: Operation with biodiesel (FAME)

 This information contains the results of the latest studies and therefore supersedes all previous information on the subject of fatty acid methyl ester (FAME). All older versions should be replaced with the current version immediately. This edition is also suitable for passing on to customers.

Notes on operation with FAME

1. Approvals

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

Preliminary remarks

Three abbreviations are common in describing fatty acid methyl ester.

 FAME Fatty acid methyl ester*

Generic term used in EU standards

 PME Plant oil methyl ester*

Generic term used previously in German-speaking areas

 RME Rape methyl ester

Fatty acid methyl ester made of rape seed oil

 On buses, operation with FAME is only possible in consultation with EvoBus.

 For models 667, 668 and 670 with engine model series 900, it is necessary to replace standard fuel lines and seals with FAME-resistant versions before operation with FAME.

 Replace leak fuel lines of injection nozzles on engine model series 400 with FAME-resistant version and connect to fuel feed.

 On OM 447hLA OEM industrial major assemblies, it is also necessary to replace the standard electrohydraulic cutoff with a FAME-resistant version.

 All of the specifications, notes and restrictions stated in this information sheet also apply to Euro -4 and Euro -5 standard engine version.

 Engines in EPA 04 and EPA 07 version (with cooled EGR) are not approved for operation with FAME.

2. Fuel

 The fuel must conform to DIN EN 14214. Operation with lower quality fuel can lead to damage and malfunctions. Daimler AG is not liable for irregularities and damage resulting from poor quality fuels.

 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.

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

3. Engine oil and maintenance

 For operation with FAME it is preferable to use engine oils as per Mercedes-Benz Specifications for Operating Fluids, Sheet 228.5 or 228.51 (approved for engine model series 457, 541, 542, 900, 902, 924, 926 with Euro 4 Standard and Euro 5 Standard without diesel particulate filter). Engine oils as per Sheet 228.3 or 228.31 (approved for the engine model series 457, 541, 542, 900, 902, 924, 926 with Euro 4 Standard and Euro 5 Standard without diesel particulate filter) can also be used if the oil change intervals are additionally shortened.

 Mercedes-Benz Specifications for Operating Fluids, Sheet 228.51 or 228.31 is not valid for model 405, 437.

 A certain quantity of fuel always mixes with the engine oil through the pistons and cylinders. Its high boiling point prevents FAME from evaporating and therefore it all remains in the engine oil. Under certain conditions, chemical reactions can occur between the FAME and engine oil. This can result in engine damage.

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

 Code MY8 (Engine oil change interval at 150,000 km) when operated using FAME leads to extended oil change intervals.

 The special version, code MJ9 (Service package, operation with FAME (biodiesel)) includes a fuel prefilter with a water separator, an additional fuel tank/combination tank for operation with auxiliary heating as well as engine-related measures. Code MJ9 (Special package, operation with FAME (biodiesel)) permits extended oil change intervals for operation with FAME.

 Extended oil change intervals for operation with FAME are possible for industrial major assemblies. To do so, the engines must be equipped with code MK21 (Engine mounted measures) and code MK04 (Fuel prefilter with water separator).

 The specified engine oil change intervals must be complied with.
Exceeding the replacement intervals can result in engine damage.

Severe operating conditions

Severe operating conditions for commercial vehicles (except Unimog) include:

 Extreme levels of short-distance hauling

 Extremely poor road conditions

 Driving with all-wheel drive

 High quantities of dust

 Operation on construction sites

 Operation of municipal vehicles or comparable operating conditions.

 Fire engine or vehicles used in agriculture and forest industry over a distance < 10,000 km per year.

 Roughly 1,000 km (or after approx. 50 operating hours) following conversion to FAME, the fuel and engine oil filters should be changed because of the risk of clogging caused by released deposits (FAME exhibits a strong cleaning effect).

 Operation with FAME requires shorter replacement intervals for the fuel filter. The fuel filter should be changed each time the oil is changed.

 Fuel filters may have a reduced service life for an extended period of time if old deposits from the fuel system are flushed into the filter. A specifically-approved fuel prefilter can be installed as an improvement measure. Vehicles with code MJ9 (Service package, operation with FAME (biodiesel)) and industrial major assemblies with code MK04 (Fuel prefilter with water separator) are already equipped with a fuel prefilter.

 The unit pumps require a very fine special fuel filter as a measure against internal wear. Installation of fuel filter elements which have not been approved leads to increased wear of the unit pumps.

4. Engine performance and cold starting

 The energy contained in the fuel means that the engine performance is reduced by approx. 8 % when FAME is used. This leads to a correspondingly higher fuel consumption in comparison to operation with diesel fuel. Correction of the engine performance is not permissible.

 Unimog: At extremely low outdoor temperatures, we recommend the installation of a flame-starting system or a charge air preheating system heating element.

 When the engine is shut down for a longer period of time, we recommend flushing with diesel fuel to avoid sticking in the fuel system. Drive for at least 30 minutes for this purpose. FAME operation is not a good idea for vehicles which are generally idle for long periods (e.g. fire service).

5. Auxiliary heaters

Generally, all auxiliary heaters can be operated with diesel fuel or fuel oil from an auxiliary fuel tank/combination tank. This solution ensures that the auxiliary heater operates properly at low outside temperatures.

6. Miscellaneous

 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 oil that exhibit ester residues from operation with FAME. Please consult your used oil dealer in this regard.

 The typical odor of the FAME exhaust gases is occasionally considered to be unpleasant, particularly after longer periods of operation at idle. On various industrial major assemblies, the odor nuisance can be reduced by the installation of an oxidation catalytic converter at the responsibility of the vehicle/equipment manufacturer.

 Daimler AG shall assume no warranty for damage resulting from the use of poor quality FAME or from any failure to observe our specifications for operation with FAME. The resulting irregularities and subsequent damage are not within our range of responsibility.