* If it's a pre-1975 engine: Many (but not all) engines from this era were designed to run on leaded fuel. While it won't immediately cause catastrophic failure, long-term use of leaded fuel in a car *not* designed for unleaded fuel won't cause significant issues.
* If it's a post-1975 engine: These engines are designed for unleaded fuel. Leaded fuel will damage the catalytic converter (if equipped) very quickly. The lead will coat the converter's internal components, rendering it ineffective. This will result in:
* Reduced engine performance: The exhaust system will be partially blocked, leading to decreased power and potentially stalling.
* Increased emissions: Harmful pollutants will be released into the atmosphere because the catalytic converter is no longer functioning properly.
* Expensive repairs: Replacing a catalytic converter is costly.
In short: Don't put leaded fuel in a 1981 Dodge Ram unless you're absolutely certain it's an engine designed for leaded fuel (and even then, it's highly discouraged due to environmental concerns). Check your owner's manual (if you have it) or the sticker under the hood for fuel recommendations. If you're unsure, stick to unleaded fuel.
