Mercedes-Benz BENZ-VEHICLES S 500 - Manual (Page 133)

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Fuel Requirements
Use only Premium unleaded meeting
ASTM standard D 439:
The octane number (posted at the pump)
must be 91 min. It is an average of both
the Research (R) octane number and the
Motor (M) octane number: [(R + M)/2].
This is also known as 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
not to exceed 15%.
The ratio of Methanol to gasoline must
not exceed 3% plus additional
cosolvents.
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
manufacturers is carbon build up caused
by gasoline. Mercedes-Benz
recommends to use only quality
gasoline containing additives that
prevent the build up of carbon deposits.
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 engine performance problems
such as:
• warm-up hesitation,
• unstable idle,
• knocking/pinging,
• misfire,
• power loss.
Do not blend other specific fuel
additives with fuel. They only result in
unnecessary cost, and may be harmful
to the engine operation.
Damage or malfunctions resulting from
poor fuel quality are not covered by the
Mercedes-Benz Limited Warranty.