Some interesting things that should be mentioned:
- Tetraethyllead, the form of lead in 100LL avgas, is designed to prevent engine knock. Engine knock, when left untreated, can cause an engine to fail. Not a big deal when you can pull off to the side of the road. A huge deal when you are flying over a populated city.
- Not all engines are certified to run on non-leaded fuel (mogas). Most of the prop planes you see in the sky are 30–40 years old. Their engines are not certified to run on normal mogas. You put them on mogas, and they will start having engine failure, and falling out of the sky.
- The FAA has been leading the charge for 3+ years developing a 100LL replacement. There are two companies who recently made it into the next round of testing to see if their fuel mixtures can fully replace 100LL w/o damaging older engines. See the following link: https://www.aopa.org/news-and-media/all-news/2016/march/29/faa-announces-unleaded-fuel-finalists
- Full disclosure: I’m studying to be a pilot and love aviation. This is a fair article that is just missing some information. Most pilots are interested in phasing out 100LL, but they don’t want to risk damaging their engines. Flying a small plane is already risky enough — no one wants to add more risks.