Well, I’ve been watching this thread from the sidelines and should probably stay there, but Oh Well. So, in the name of TMI….
I won’t critique anyone who wants to go thru the trouble of getting 100LL in their car tank. Their business, not mine. BUT, there are other octane additives out there designed for autos.
I’m a serial consumer of 100LL in airplanes and helicopters and even gliders (tow plane burns it) so I realize that its transportations leading contributor to lead emissions in the atmosphere. Not good. Thusly, 100LL has been on the hit list to eliminate for 20 years or more. That effort has gained traction in the past couple years. Several aviation organizations have teamed up to try to lead the development of a replacement fuel that all piston aircraft can use without expensive modifications to aircraft but solutions are extremely complicated and expensive for a relatively low market share of fuel. The goal is a replacement fuel by 2030. Many low power (less than 200 hp) airplane engines have been approved to use unleaded non-ethanol MOGAS thru a supplemental type certificate. High hp engines, no good solutions exist…yet. Like all fuels, 100LL prices are out of control, sometimes north of $7 a gal. My Cessna 182 sips 12.1 gals per hour in cruise. I don’t do the math anymore. A friend’s DH-2 Beaver burns 25-28 GPH. Ouch!
Detonation (different than preignition) in aircraft is a real threat that can quickly reduce an engine to ruin and unlike your car, you can’t hear it (pinging/knocking) because of ambient noise. Hopefully, you can find a suitable airport or landing area before it comes apart. If youre paying attention to cylinder head temp, you may recognize it in time. Reciprocating engine airplanes spend most of a flight running at 65% and higher of rated max horsepower, helicopters even higher percentage of rated horsepower for nearly the entire flight. We don’t do that to a streetcar day after day after day.
Here's some great pics of detonation/preignition damage.
https://www.faasafety.gov/files/notices/2019/Jul/Preignition.pdf
If you want to know more about 100LL, here’s a link.
https://www.aviationpros.com/engine...ne-first-meeting-seek-solution-to-leaded-fuel