Saab 3-Sep Automobile User Manual


 
149Starting and driving
Recommended fuel:
For optimum performance we recommend
90 AON for 175 hp engines and 93 AON for
210 hp engines.
Octane rating is determined according to
the formula:
where MON is the Motor Octane Number,
and RON is the Research Octane Number.
The average of these two values is the
octane rating of the gasoline as it appears
on the pump at a retail gas station. This
value is sometimes referred to as the "Anti-
Knock Index" (AKI) or the "Average Octane
Number" (AON).
To avoid deposit formation on the fuel injec-
tors which can cause poor driveability, use
only quality gasolines that contain deter-
gents and corrosion inhibitors. Because
gasolines sold at retail gas stations vary in
their composition and quality, you should
switch to a different brand if you begin expe-
riencing driveability and/or hard starting
problems shortly after refueling your car. In
recent years, a variety of fuel additives and
alcohols or oxygenates have been blended
with gasoline. These types of gasolines may
be found in all parts of the United States and
Canada, but particularly in geographic
areas and cities that have high carbon
monoxide levels. Saab approves the use of
such "reformulated" gasolines in its prod-
ucts, which help in reducing pollution from
all motor vehicles, provided that the follow-
ing blending percentages are met by such
fuels:
Up to 10 % ethanol by volume, with corro-
sion inhibitors.
Up to 15 % MTBE by volume (methyl
tertiary butyl ether).
Up to 5 % methanol by volume, with an
equal amount of a suitable co-solvent and
added corrosion inhibitors.
Other, less common, fuel additives used by
some gasoline dealers are also acceptable,
provided that the resultant gasoline is not
more than 2.7 % oxygen by weight. In many
cases, you may not be able to determine the
exact type or percentage by volume of fuel
additive in the gasoline you purchase for
your car.
Some Canadian and U.S. gasolines contain
an octane enhancing additive called meth-
lycyclopentadienyl manganese tricarbonyl
(MMT). If such fuel is used, your emission
control system performance may deterio-
rate and the malfunction indicator lamp on
your instrument panel may turn on. If this
occurs, return to your authorized Saab
dealer for service.
However, these blended gasolines are reg-
ulated and should never exceed these rec-
ommended blend percentages and service
station operators should know if their gaso-
lines contain detergents and oxygenates,
and have been reformulated to reduce vehi-
cle emissions. Nevertheless, if you begin to
notice a problem with the way your car starts
or runs shortly after it has been refueled, try
a different brand of gasoline.
MON + RON
2