While leaded gasoline was common in 1967, using it now is extremely detrimental for several reasons:
* Damage to the catalytic converter: If your Mustang has a catalytic converter (even a later addition), leaded gas will ruin it. The lead will coat the catalytic converter's internal components, rendering it ineffective and potentially causing serious engine damage.
* Environmental damage: Leaded gasoline releases lead into the atmosphere, which is a serious neurotoxin. Its use is heavily restricted and illegal in most places.
* Damage to oxygen sensors: Modern engines rely on oxygen sensors for precise fuel control. Lead will contaminate and destroy these sensors.
* Internal engine damage: While some older engines were *designed* for leaded gasoline, using it in an engine not designed for it can still cause damage over time. Even if your 1967 Mustang's engine *could* tolerate it (which is debatable given its age and potential for wear), the benefits are vastly outweighed by the risks.
Instead of using leaded gasoline, you should use a modern, unleaded gasoline with the appropriate octane rating for your engine. If you have concerns about valve seat recession (a common issue with older engines running unleaded fuel), you can use a fuel additive designed to protect against this, or have your valve seats hardened. These are far safer and more effective solutions than resorting to leaded fuel.
