Mercedes-Benz 190 E 2.3 1991, Owner'S Manual

Page: 115 / 129

Use only Premium unleaded meeting
ASTM standard D 439:
The octane number (posted at the
pump) must be 91 min. It is an aver­
age 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 oxy­
genates such as Ethanol, MTBE, IPA,
IBA and TBA can be used provided
the ratio of any one of these oxy­
genates to gasoline does not exceed
10%.
Fuel Requirements
The ratio of Methanol to gasoline must
not exceed 3% plus additional cosol­
vents.
Using mixtures of Ethanol and Metha­
nol is not allowed. MTBE may, how­
ever, be added up to 15%. 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..
A major concern among engine manu­
facturers is carbon build up caused by
gasoline. MERCEDES-BENZ recom­
mends 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 depo­
sits can build up especially on the in­
take valves and in the combustion
area, leading to engine performance
problems such as:
• warm-up hesitation,
• unstable idle,
• knocking/pinging,
• misfire,
• power loss.
Damages or malfunctions resulting
from poor fuel quality are not covered
by the MERCEDES-BENZ Limited
Warranty.
Gasoline Additives
113