688 Technical data
Fuels, coolants, lubricants, etc.
Fuel requirements
Only use premium unleaded fuel:
The octane number (posted at the
pu m p) m us t b e 91 mi n. It is an a vera ge
of both the Research Octane Number
(RON) and the Motor Octane Number
(MON): (RON+MON)/2. This is also
known as the ANTI-KNOCK INDEX.
Unleaded gasoline containing oxygenates
such as ethanol, IPA, IBA and TBA can be
used provided the ratio of any one of these
oxygenates to gasoline does not
exceed 10%; MTBE must not exceed 15%.
The ratio of methanol to gasoline must not
exceed 3% plus additional co-solvents.
Using mixtures of ethanol and methanol is
not allowed. Gasohol, which contains
10% ethanol and 90% unleaded gasoline,
can be used.
These blends must also meet all other fuel
requirements, such as resistance to spark
knock, boiling range, vapor pressure, etc.
Gasoline additives
A major concern among engine manufac-
turers is carbon build-up caused by gaso-
line. Mercedes-Benz recommends only the
use of quality gasoline containing additives
that prevent the build-up of carbon depos-
its.
After an extended period of using fuels
without such additives, carbon deposits
can build up especially on the intake valves
and in the combustion area, leading to en-
gine performance problems such as:
Warm-up hesitation
Unstable idle
Knocking/pinging
Misfire
Power lossIn areas where carbon deposits may be en-
countered due to lack of availability of gas-
olines which contains these additives,
Mercedes-Benz recommends the use of
additives approved by us for use on
Mercedes-Benz vehicles. Refer to the
Factory Approved Service Products pam-
phlet (USA only) or contact an authorized
Mercedes-Benz Center of listing of ap-
proved product(s). Follow directions on
product label.
Do not blend other fuel additives with fuel.
This only results in unnecessary cost and
may be harmful to the engine operation.
!Damage or malfunction resulting from poor
fuel quality or from blending additional fuel addi-
tives other than those tested and approved by us
for use on Mercedes-Benz vehicles are not cov-
ered by the Mercedes-Benz Limited Warranty.
For a listing of approved products, refer to the
Factory Approved Service Products pamphlet
(USA only) or contact an authorized
Mercedes-Benz Center.
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