What are the main differences between grades 100 and 100LL?

What are the main differences between grades 100 and 100LL?

• A. Octane rating
• B. Volatility
• C. Density
• D. Lead content and color

Answer: (D)

The key idea is that these two aviation gas grades differ mainly in additives that you can actually notice: lead content and color. Both are high-octane fuels used in piston aircraft engines, so their octane rating is not the distinguishing factor here. The “LL” in 100LL stands for low lead, meaning it still contains some tetraethyl lead as an anti-knock additive, but less than older leaded fuels. It is dyed blue to help you tell it apart from other fuels in the system. The other grade, simply 100, is essentially the high-octane fuel without the lead additive and is not colored by dye. So the practical differences you’ll notice are the lead content and the color, which helps prevent misfueling and informs maintenance considerations related to lead deposition.

The key idea is that these two aviation gas grades differ mainly in additives that you can actually notice: lead content and color. Both are high-octane fuels used in piston aircraft engines, so their octane rating is not the distinguishing factor here. The “LL” in 100LL stands for low lead, meaning it still contains some tetraethyl lead as an anti-knock additive, but less than older leaded fuels. It is dyed blue to help you tell it apart from other fuels in the system. The other grade, simply 100, is essentially the high-octane fuel without the lead additive and is not colored by dye. So the practical differences you’ll notice are the lead content and the color, which helps prevent misfueling and informs maintenance considerations related to lead deposition.