What is the required fuel grade for the Cessna 172?

The required fuel grade for the Cessna 172 is 100LL Avgas. This type of fuel is specifically formulated for aircraft engines and contains a tetraethyl lead additive that provides better anti-knock properties, which is essential for higher-compression piston engines like those found in the Cessna 172. The "LL" in 100LL stands for "low lead," which means it has a lower amount of lead compared to other avgas types, ensuring it meets modern environmental standards while still providing the performance required for safe flight operations.

Using the correct fuel is critical, as using fuels with lesser octane ratings, such as Jet B fuel or AVGAS 82UL, could lead to engine knocking or pre-ignition. These outcomes can severely damage the engine, leading to expensive repairs and potentially dangerous flight situations. Higher octane fuels like 91 octane are not suitable as they are not designed for aviation use and lack necessary additives, making 100LL the only appropriate fuel grade for the Cessna 172.