Marvel mystery oil used as a lead substitute?

mderoy340 said

4 oz to 10 gallons for fuel. MM was developed for radial aircraft engines in WW2 era. Google it and you can find an article of the development, it's a good read.
I would run what you have and not worry about it. You may have induction hardened and not even know it. The auto industry knew unleaded fuel mandate was coming and didn't wait until 1973.

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Hmm, on their website the reason they give for its development is different.

“Founded in 1923 by Burt Pierce, the brand has remained legendary for over 90 years. Pierce’s reputation for ingenuity preceded him as he was already well-known for inventing the Marvel Carburetor, standard equipment on 80% of all vehicles produced after World War I. Vehicles of the post WWI era encountered carburetor problems, the most perplexing being clogged jets due to high lead content and other contaminants found in the gasoline of the time. The problem motivated Pierce to direct his creative ingenuity towards formulating a blend of chemicals and petroleum products to clean and maintain clogged jets. He was successful beyond his wildest expectations and the legend of MMO was born.”

Sounds to me like it was developed to clear clogged carburetor jets due to high lead content.