Comments by "spaceflight101" (@spaceflight1019) on "Engineering Explained" channel.

You need to explain where you could find leaded pump gas in the United States after the early 1980s. Low-lead gas began appearing in 1971. After the 1973 Arab oil embargo octane ratings were reduced to what we have today. Unleaded gas coincided with the 1975 cars and the introduction of the catalytic converter. A secondary benefit of leaded gas was as a valve seat lubricant. Engines had their valve seats cut directly into the cast iron of the cylinder head. Specially hardened valve seats of Stellite solved this problem. Racing gas and lead additives were never used in enough volume to affect anything. General aviation still uses leaded avgas, but with the overall decline in use and ownership how much of a problem is it? The airport near me was a bustling center of general aviation 50 years ago, today it's a corporate aviation center favored by the Gulfstream crowd.
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