Why do old cars still need leaded gasoline?

Old cars don't *need* leaded gasoline, but they often *run better* on it. The reason is that leaded gasoline contains tetraethyllead, which acts as a lubricant for the valve seats in older engines. Many older engines, especially those built before the widespread adoption of unleaded fuel in the 1970s, have softer valve seats made of materials that are more prone to wear and damage without the lubricating properties of lead. Using unleaded fuel in these engines can lead to:

* Valve seat recession: The valve seats can wear down and become pitted, leading to poor compression and engine performance.

* Burnt valves: Excessive wear can cause valves to burn and fail.

Therefore, while it's illegal and environmentally damaging to use leaded gasoline in most places (due to the extreme toxicity of lead), some owners of classic cars *choose* to use it to preserve their engines, recognizing the potential for damage with unleaded fuel. However, there are alternatives like hardened valve seats and fuel additives that can mitigate the risk of damage from unleaded gasoline. Many classic car owners opt for these solutions to avoid the environmental and legal consequences of using leaded fuel.