What key feature distinguishes AVGAS 100LL from AVGAS 100?

The key feature that distinguishes AVGAS 100LL from AVGAS 100 is its lower lead content. AVGAS 100LL, where 'LL' stands for 'low lead,' is formulated to contain significantly less tetraethyl lead compared to AVGAS 100. This reduction is critical as it aligns with global trends toward decreasing lead exposure and improving environmental conditions.

The lead content in AVGAS 100LL helps to minimize pollution and the potential for lead-related health issues, making it a more environmentally friendly option for aviation fuel, especially in light of increasing regulatory scrutiny regarding lead emissions. This distinction makes AVGAS 100LL more appealing for aircraft operators seeking to comply with environmental standards while also providing reliable fuel performance.

The other options, while relevant to fuel characteristics, do not specifically define the primary difference noted between these two aviation fuels. Thermal efficiency, environmental impact, and combustion temperature are important factors but are not the fundamental differentiators between AVGAS 100LL and AVGAS 100.