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#1
Old 05-02-2000, 02:01 AM
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When I was a kid, I remember one of the choices my father had at the gas station was called "Ethel". What exactly was that? Is it the same as the reformulated gas we use here in Wisconsin & over in Iowa (10% corn alcohol added to gasoline). What benefit was there in using it?
#2
Old 05-02-2000, 02:10 AM
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"Ethyl" gasoline corresponded to "premium" gas nowadays. The difference was the addition of tetraethyl lead to the gas, which boosted octane and also protected the engine against wear (the lead plated onto the cylinder walls, and being soft, was easily scraped away by the piston rings. The end result was better compression.) They stopped with the tetraethyl lead when somebody noticed lead was toxic, and maybe it wasn't the greatest idea to spew it out of tailpipes nationwide. Thus, the big move to unleaded in the Seventies.
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#3
Old 05-02-2000, 02:25 AM
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Never heard the "coating the cylinders" theory before. I always thought the lead was to coat the valves and valve seats to cut down on chatter and to keep the valves from chipping and dropping crap into the jugs. Thats why older engines required so much "break in" time- so the valves got a good layer of lead before you opened 'er up. Anyone?
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#4
Old 05-02-2000, 02:28 AM
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Cowboy Greg is correct. They called it Ethyl Gasoline largely because tetraethyllead was made exclusively by the Ethyl Corporation for many years. Its composition was a trade secret. Its use is credited to an engineer named Thomas Midgley, Jr., who worked on the engine-knocking problem in the 1920s. Automotive Gasoline has a good discussion on the subject.
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#5
Old 05-02-2000, 07:34 AM
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Sorry I was late.

Tetraethyl Lead (Pb(C2H5)4) was originally intended for use as a antiknock agent, however it was also discovered that the lead deposits provided lubrication for the valve seats. While it does also form deposits on the cylinder walls, this effect is not considered beneficial per se. If the TL content of the fuel is too high, it can cause spark plug fouling and troublesome deposits on the valve stem, which can reduce valve cooling and cause premature exhaust valve failure (but the seats will sure look good!)

This effect can be reduced by adding an organic halide, such as ethylene dibromide. When combined with TL, this mixture used to be called "ethyl fluid" .
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#6
Old 05-02-2000, 08:03 AM
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Lead tetraethyl was never a necessary component of gasoline. It caused more engine wear than it prevented. This chemical put seven million tons of lead into the soil of the U.S., most of which is still there. It was mainly responsible for high levels of lead in the blood. Many countries, especially in the third world, still use it in much higher concentrations than was used here.

It was always known to be dangerous. Standard Oil, GM, and the DuPonts, however, didn't care. It was profitable. The Nation magazine, http://thenation.com, had an excellent ten-page article on this subject in the last few months.
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#7
Old 05-02-2000, 11:39 AM
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Aviation fuel

Lead is still required in most IC aircraft engines. Even engines with supplemental type certificates (STC) to run on unleaded auto fuel must use leaded aviation fuel for break in. I believe this is due to the valve train design and materials (seats, stems,guides) being stuck in the 1940's.

I plan on running leaded fuel in my aircraft for the first 100 hours, and then mix 50/50 with auto fuel after that to reduce plug fouling but still retain lubrication.

There is a new gas formulation coming out with reduced lead for use in engines that previously used the lower lead (80/87) fuel that is no longer available.
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