Mercedes-Benz C 250 Coupe, Operator'S Manual

Page: 331 / 336

If there is no premium-grade unleaded
gasoline available and regular-grade
unleaded gasoline may be used; please
observe the following precautions:
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only fill the fuel tank to half full with
regular-grade unleaded gasoline and fill
the rest with premium-grade unleaded
gasoline as soon as possible.
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do not drive at the maximum speed.
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avoid sudden acceleration.
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if the vehicle is carrying a light load, e.g.
two passengers without luggage, do not
allow the engine to rev above
3,000 rpm.
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if the vehicle is fully loaded or is being
operated in mountainous terrain, do not
depress the accelerator pedal further
than
Ô
of the pedal travel.
Fuel requirements
Use only premium-grade unleaded gasoline.
The octane number should be at least 91.
Details can be found on the gas pump. The
octane number is the average value of the
Research Octane Number (RON) and the
Motor Octane Number (MON): (RON +
MON) / 2, also known as knock resistance.
Reformulated gasoline (RFG) and/or
unleaded gasoline with additives can be used.
However, the concentration of additives in
the fuel must be less than 10%, e.g.
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Ethanol
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TAME
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ETBE
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IPA
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TBA
For MTBE, the concentration should not
exceed 15%.
The concentration of methanol in gasoline
including other additives must not exceed 3%.
Using mixtures of methanol and ethanol is not
permitted. Gasohol, a mixture of 10% ethanol
and 90% unleaded gasoline, can be used.
All of these mix fuels must fulfill the fuel
requirements, e.g.:
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knock resistance
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boiling point
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vapor pressure
Additives in gasoline
One of the main problems of poor fuel quality
is the forming of deposits that are created
during the gasoline combustion process.
Mercedes-Benz recommends that you use
fuel brands that have the additives.
Deposits may form if you use fuels without
additives over a longer period of time. These
deposits are most likely to form on the inlet
valves and in the combustion chamber.
This could lead to engine problems, e.g.:
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longer engine warm-up phase
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uneven idle
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engine noise
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misfiring
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loss of power
Carbon deposits may form if the availability
of gasoline with relevant additives is
insufficient (in certain regions). In this case,
Mercedes-Benz recommends the use of
additives that have been approved for
Mercedes-Benz vehicles.
Consult an authorized Mercedes-Benz Center
or go to the Internet site
http://www.mbusa.com (USA only) for a list
of approved products. Comply with the
instructions for use on the product label.
Do not mix other fuel additives with fuel. This
causes unnecessary costs and could damage
the engine.
! Do not refuel with low-grade fuel and do
not use fuel additives that are not tested
and approved for Mercedes-Benz vehicles.
Damage to or malfunctions of the fuel
system may otherwise occur.
Service products and capacities
329
Technical data
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