[davnicwil]

it's incredibly surprising to me that lead was added to gasoline specifically at all.

I'd always assumed it was some expensive-to-remove byproduct of manufacture or something, so they left it in to save costs despite the risks.

Why did this happen?

[pixl97]

Lead in gas increased compression rations and allowed us to build higher horsepower engines. Lead is still used in avgas for this reason. Engine knock was a big problem at the time.

[margalabargala]

I wonder about lead levels in soil near gen aviation airports for this reason, and in the neighborhoods that sometimes get built on decommissioned runways.

[potato3732842]

I assume it's pretty inconsequential because if it weren't I'd hear real people talking about it (like with lead paint, and various forms of soil contamination) and as it stands I only hear fake internet comment section hand wringers hand wringing about it.

[Der_Einzige]

I'm sure you'd regard something like banning tail docking, ear cropping, or non medically necessary infant circumcision as similarly unimportant because only weird "chronically online" folks talk about it. "Just hand wringers". This is why the world is full of cruelty.

[margalabargala]

Per the article we're all commenting on that's maybe not the wisest assumption.

What makes the difference between a fake hand wringer and a real one, by the way? Whether or not this happen to be standing near you at the moment?

[LorenPechtel]

AFIAK only permitted in some old engines that were designed to need the lead.

[chasil]

As I understand it, both tetra ethyl lead and ethyl alcohol are anti-knock agents.

Lead was used because it was cheaper.

https://en.wikipedia.org/wiki/Antiknock_agent

[potato3732842]

Ethanol has other downsides regarding corrosion and reacting with various organic and organic-ish (read: rubber) components. Those were bigger problems back then because everything was carbureted and they didn't have modern plastics.

[consp]

Ethanol on its own is an anti knock agent. E85 is RON 105 for instance.

[ants_everywhere]

according to the article

> Oil companies and automobile manufacturers (especially General Motors, which owned the patent jointly filed by Kettering and Midgley) promoted the TEL additive as an inexpensive alternative superior to ethanol or ethanol-blended fuels, on which they could make very little profit.

Functionally, as others have commented, it is there to reduce knocking. But lead was used instead of ethanol (aka alcohol) because it was more profitable despite being poisonous.

[kragen]

It also gave better gas mileage.

[marcosdumay]

It allowed people to use engines with better gas mileage, what is a different thing.

Just adding the lead addictive to gasoline reduced your gas mileage. But it made better engines work.

[kragen]

It surely reduced it by a tiny amount compared to just straight octane, but ethanol reduced it by something like 10%. So using TEL instead of ethanol gave you about 10% higher gas mileage.

[marcosdumay]

If you are comparing it to pure ethanol, yeah, that's the ballpark.

Leaded gas compared to ethanol mixed gas with equivalent octane numbers should have something around 1% or 2% difference.

[kragen]

https://en.wikipedia.org/wiki/Energy_density#Chemical_reacti... says "Gasohol E10 (10% ethanol 90% gasoline by volume)" is 33.18MJ/liter, while "Petrol (Gasoline)" is 34.2MJ/liter. That's a 3% difference, which is much closer to your 1% or 2% than to the 10% I had believed. E85 is lower still in energy density.

All of this is assuming the engine has the same efficiency on both fuels, rather than, for example, using a much higher compression ratio on the ethanol.

[consp]

At worst to get equivalent octane rating you lose about 4 percent in power density. In practice you won't notice due to the slightly more efficient burning of alcohol.

[kragen]

I don't think that is correct.

[JJMcJ]

Tetraethyl Lead was an octane raiser - an anti-knocking compound.