Diagnosing Fuel Quality Problems: Additives

Additives are blended with gasoline for better performance. Gasoline typically contains several of the following:

1. Anti-Knock Agents
   
   MTBE and ethanol (oxygenated fuels) are the two most common antiknock agents. Toluene (aromatic hydrocarbon) is another common antiknock additive.
2. Detergent/Deposit Control Agents
   
   Detergents and deposit control agents are found in most fuels to help prevent and, in some cases, remove deposits from the throttle body, intake manifold, ports, fuel injectors, and valves.
3. Anti-Oxidants
   
   Anti-oxidant additives stabilize fuel during storage and shipment, which helps reduce gum formation.
4. Metal Deactivators
   
   A metal deactivator inhibits the oxidation of the fuel which is catalyzed by trace metals such as copper.
5. Corrosion Inhibitors
   
   Corrosion inhibitors prevent the corrosion of iron.
6. Dyes
   
   Dyes are used to identify different fuel grades and brands (by color).
7. Anti-Icing Agents
   
   Anti-icing agents help prevent ice formation that may cause restrictions and possible stalls. In cold weather, as humid air passes over a throttle plate, moisture can condense and freeze on the throttle plate.