[drzoltar]

Have there been any publicized studies done on the reliability of aircraft engines, with and without lead? I’m guessing this is what made the transition take so long, but I can’t seem to find any references.

[strangemonad]

It’s a rather complex topic with all sorts of factors including economics of a small market and FAA red tape. Av web has a great multi part on failure modes of engines and why new engines often don’t succeed

https://youtu.be/mwpzTnLC8BY

https://youtu.be/_k1TQGK3mZI

[p_l]

Another problem is, IIRC, that many replacements for leaded fuels have evaporation & performance issues at lower pressures that don't matter in a car but can be critical in airplane (it's even worse with ethanol additives, IIRC).

[phoenix3200]

There are some claims out there that engines run better without lead (it eats away at seals and whatnot).

[ericpauley]

Also fouls spark plugs, sticks valves, contaminates oil, and covers the underside of the plane. Leaded avgas is all-around nasty stuff.

[hugh-avherald]

I can't find it, but NASA concluded that piston engine reliability is generally a mystery.