What is unleaded gas?

Unleaded Gasoline: An Overview

Unleaded gasoline is a type of gasoline that does not contain lead compounds. Historically, lead, specifically tetraethyllead (TEL), was added to gasoline as an antiknock agent to increase its octane rating and reduce engine knocking.

Why Unleaded?

The primary reason for switching to unleaded gasoline was due to the environmental and health hazards associated with lead emissions. Lead is a neurotoxin that can accumulate in the body, causing a range of health problems, especially in children. Furthermore, leaded gasoline contaminates the environment, affecting soil, water, and air quality.

Composition of Unleaded Gasoline

Unleaded gasoline is a complex mixture of hydrocarbons, including alkanes, alkenes, and aromatic compounds. Refineries use various blending techniques to achieve the desired octane rating and performance characteristics. Alternative antiknock additives, such as ethanol and methyl tertiary butyl ether (MTBE), are used to boost octane levels.

Environmental Benefits

The phase-out of leaded gasoline has had a significant positive impact on public health and the environment. Reduced lead exposure has led to improved cognitive development in children and decreased rates of lead-related illnesses. Air quality has also improved, particularly in urban areas.

Compatibility

Most modern vehicles are designed to run on unleaded gasoline. However, older vehicles designed for leaded gasoline may require modifications or the use of lead substitutes to prevent engine damage.

Octane Grades

Unleaded gasoline is typically available in various octane grades, such as regular (87 octane), mid-grade (89 octane), and premium (91-93 octane). The appropriate octane level for a vehicle is usually specified in the owner's manual.