No, you should never put 151-proof alcohol (75.5% alcohol by volume) in your car's fuel tank. It is not a safe or effective substitute for gasoline or approved fuel additives. Using such a high-concentration alcohol can cause severe damage to your vehicle's fuel system and engine components, which are not designed to handle it. It is also illegal in many places to use non-taxed, non-denominated alcohol as motor fuel.
The primary risk involves compatibility. Modern fuel systems include rubber seals, plastic components, and metal parts that can be corroded or degraded by high-proof alcohol. This can lead to fuel leaks, which are a major fire hazard. Furthermore, your engine's computer is calibrated for a specific fuel mixture; introducing a high-alcohol content can cause improper combustion, leading to poor performance, engine knocking, and potential long-term damage.
For context, standard E10 gasoline contains only 10% ethanol. Even E85 flex-fuel, designed for high-alcohol blends, contains only 51-83% ethanol and requires a specifically engineered vehicle. The jump to 75.5% alcohol in a standard car is extreme and dangerous.
| Aspect | 151-Proof Alcohol | Approved Fuel Additive (e.g., ISO-Heet) |
|---|
| Alcohol Content | 75.5% | Typically 99%+ Isopropyl Alcohol |
| Primary Purpose | Consumption | Absorbing water in the gas tank |
| Effect on Fuel System | Can degrade seals, gaskets, and lines | Safe for occasional use in small quantities |
| Combustion | Can cause engine knocking and damage | Burns cleanly in small doses |
| Legality for Fuel Use | Illegal (avoids fuel taxes) | Legal when sold as a fuel additive |
| Cost per Ounce | Low (for consumption) | Higher (specifically formulated) |
If you're dealing with issues like water in your gas tank, use a product specifically designed as a fuel additive. These are formulated to be safe for your engine while effectively removing moisture. Pouring liquor into your gas tank is a costly mistake that will likely lead to expensive repairs.
