Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DRIVEABILITY Symptoms Versus Fuel Quality (Engine Systems Functioning Properly): Additives
Additives are blended with gasoline for better performance. Gasoline typically contains several of the following:
Antiknock Agents - MTBE and ethanol (oxygenated fuels) are the two most common antiknock agents. Toluene (aromatic hydrocarbon) is another common antiknock additive.
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.
Anti-oxidants - Anti-oxidant additives stabilize fuel during storage and shipment, which helps reduce gum formation.
Metal Deactivators - A metal deactivator inhibits the oxidation of the fuel which is catalyzed by trace metals such as copper.
Corrosion Inhibitors - Corrosion inhibitors prevent the corrosion of iron.
Dyes - Dyes are used to identify different fuel grades and brands (by color).
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.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.