Banning lead in gas worked. The proof is in our hair

Actually, moisture problems are from using things like homemade alcohol or alcohol from unknown sources, where the likelihood of it already containing a sizable percentage of water has been a problem since the Model T days.

And if that water has a bit of an aggressive pH, it can have an effect on aluminum components.

This is just not a problem with gasoline-alcohol blends from reputable suppliers unless there is serious failure in the supply chain after that, where any fuel would have been contaminated by water regardless. The fuel-grade alcohol is tested before it is added, then the finished gasoline fully analyzed afterward.

Neither moisture nor corrosion is a problem with fuel ethanol or methanol, and when you see convincing information to the contrary (like from a pro mechanic) it often originates from misguided sources, "old wives' tales" for which actual evidence existed without being well-understood. But sometimes the most professional are the ones who don't take any chances, whether "common knowledge" is factual or not, if it doesn't hurt, no big deal.

Miscellaneous polymer compounds were the real question for cars that were not originally made for modern alcohol mixtures.

Ethanol just doesn't absorb moisture into your fuel tank by itself, even from a very humid environment.

Not any more than plain hydrocarbon fuel. In old ventilated fuel tanks, extreme temperature cycling under very humid conditions draws moist air into the tank when the fuel shrinks or is consumed. Kilos of cold fuel and cold metal can continue to condense moisture from the air, when the dew point is greater than the temperature of the tank. After a while you can get grams or ounces of water rolling around in the bottom of the tank. This could build up and stall out the vehicle or keep it from starting.

If it was only an ounce or two of water at the bottom of the tank full of all hydrocarbons, it would actually help to add a gallon of plain (good) alcohol to help dissolve the separated water into the gasoline so it can pass through harmlessly like it always has since gasoline has always had trace amounts of water anyway. Condensation is about as clean as rainwater so it's nothing the engine hasn't seen.

When most mechanics see something like this it has already gotten way out of hand, and there have been waves of anti-alcohol propaganda disseminated through time which reinforce the superstitious component.

Another problem from the '80's was when you do first start using alcohol-containing gasoline in an older car, it can break up varnish that has built up in the tank for years which never would come off until some alcohol came along. This could be a few grams, end up clogging the fuel filter, and the car stalls out no different than from water in the fuel line. Direct cause-and-effect relationship undeniably due to the use of alcohol, with many independent observations. Not a water problem, but who's keeping score.

Just not any more of a problem in the 21st century, similar conditions are so rarely encountered now.

There's been some trials of battery-powered trainer aircraft. The last I checked, they still don't have enough range to do the "long" cross country that's legally required.

And I assure you it's not because of old aircraft. Some flights schools have fleets of brand new 2025/26 models - all of them still run on leaded avgas.

Yes, not just environmental, all kinds of money stuff. The more money can be how it gets on steroids.

But this says a lot here:

>not try to condense it down to something overly simplistic

With greed involved you can follow the money to an extent, you find lobbyists on both sides of every controversy, sometimes chalking up wins, other times losses. But they stay in business and grow by compromising the greater good with as little profit loss from those paying them the most.

They might switch roles when they lobby in favor of ordinary citizens one time, and squarely against in a future campaign. But they never actually switch sides, the least costly thing to compromise is the "greater good", which ideally from their point of view is intangible, versus actual money, which their clients are usually counting before they have earned any.

It's politics, all regulations are hard to pass, but as lobbying has increased, the difficulty of having good legislation in favor of the greater good is becoming less possible.

It just costs too much to have a seat at the table.

If people want to have good things, it might become completely dependent on older regulations which were in their favor before it got too expensive to do that any more.

They started looking at it 14 years ago, but there's been tons of bureaucratic roadblocks that have impeded progress. (Depending on who you ask, the petroleum companies were responsible for some of these.)

Even today, there are reports that the new unleaded avgas formulations cause engine damage, and we don't entirely know why that's happening. So there's still technical issues to work out. (But it's important, so folks are trying to solve them as quickly as possible.)