What is the primary difference between AVGAS 100 and AVGAS 100LL?

The primary difference between AVGAS 100 and AVGAS 100LL lies in their lead content and formulation. AVGAS 100 is a high-octane fuel that contains a higher concentration of tetraethyl lead, which is used to enhance performance and prevent knock in piston engines. On the other hand, AVGAS 100LL (low lead) has been specifically formulated to contain a lower level of lead to reduce environmental impact and comply with regulations regarding lead emissions.

This distinction is important for aircraft operations as it ensures that pilots and aircraft operators can choose a fuel that meets engine requirements while also being mindful of environmental considerations. While both fuels are designed for use in aviation piston engines and share some similar performance characteristics, the lead content is the key differentiator that affects regulatory compliance and operational sustainability.

The other options do not accurately reflect this critical aspect of difference in the formed blends of the two AVGAS types.