2004 Saab 9-3 Owner's Manual - Page 149

Starting 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: MON + RON 2 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 "AntiKnock Index" (AKI) or the "Average Octane Number" (AON). To avoid deposit formation on the fuel injectors which can cause poor driveability, use only quality gasolines that contain detergents 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 experiencing 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 products, which help in reducing pollution from all motor vehicles, provided that the following blending percentages are met by such fuels: • Up to 10 % ethanol by volume, with corrosion 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. 149 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 methlycyclopentadienyl manganese tricarbonyl (MMT). If such fuel is used, your emission control system performance may deteriorate 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 regulated and should never exceed these recommended blend percentages and service station operators should know if their gasolines contain detergents and oxygenates, and have been reformulated to reduce vehicle 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.