Fuel Requirements; Gasoline Additives - Mercedes-Benz S 320 1999 Owner's Manual

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, I PA,
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 addition­
al 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 the use of 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 or from
blending specific fuel additives are
not covered by the Mercedes-Benz
Limited Warranty.