Mercedes-Benz CLS-Class 2012 Owners Manual - Manual (Page 350)

Direct skin contact with fuels and the
inhalation of fuel vapors are damaging to your
health.
Premium-grade unleaded gasoline
!
To ensure the longevity and full
performance of the engine, only premium-
grade unleaded gasoline must be used.
If no premium-grade unleaded gasoline is
available and regular unleaded gasoline
must be used, observe the following
precautions:
R
only fill the fuel tank to half full with
regular unleaded gasoline and fill the rest
with premium-grade unleaded gasoline
as soon as possible.
R
do not drive at the maximum speed.
R avoid sudden acceleration.
R when the vehicle is carrying a light load,
e.g. two passengers without luggage, do
not allow the engine to rev above
3000 rpm.
R when the vehicle is fully loaded or in
mountainous terrain, do not depress the
accelerator pedal further than ⅔ 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
if the concentration of the additives in the fuel
does not exceed 10%, e.g.:
R
Ethanol
R
TAME
R ETBE
R IPA
R
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.:
R knock resistance
R boiling point
R
vapor pressure
Additives in gasoline
One of the major problems with poor quality
fuels is the creation of carbon deposits during
the combustion process. Mercedes-Benz
recommends that you use fuel brands
containing additives that prevent the build-up
of carbon deposits.
If you use fuels without these additives for an
extended period of time, there may be a build
up of carbon deposits, especially on the inlet
valves and in the combustion chamber.
This could lead to engine running problems,
e.g.:
R longer engine warm-up phase
R
uneven idle
R
engine noise
R
misfiring
R
loss of power
In areas where the availability of gasoline with
relevant additives is not adequate, carbon
deposits can form. 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. Observe the
instructions for use on the product label.
348
Service products and capacities
Technical data