How to tell if gas in the can has gone bad

Symptoms

• Gas smells sour, sharp, or like varnish instead of normal gasoline
• Fuel looks darker or cloudy compared to fresh gas
• Equipment that used this gas is hard to start or runs rough
• Fuel has been stored more than a few months

Likely causes

• CommonOxidation from age and air exposureGasoline components break down over time, especially in partially filled containers with more air space.
• CommonEthanol absorbing moistureEthanol-blended gas can absorb water from humid air, degrading fuel quality and causing phase separation.
• PossibleHeat exposure during storageStoring fuel in a hot garage or shed speeds up degradation.

What to do

1. Smell the fuel; a sour or varnish-like odor instead of normal gasoline smell indicates it has degraded.
2. Look at the color; fresh gas is typically light amber, while degraded fuel often looks darker or cloudy.
3. Check for a separated layer at the bottom of a clear container, which indicates ethanol has absorbed water and separated.
4. If gas is more than 3–6 months old or shows any of these signs, don't use it in equipment.
5. Dispose of bad gasoline at a household hazardous waste facility or auto parts store that accepts it; never pour it down a drain or onto the ground.
6. Going forward, buy only what you'll use within a month or two, or add a fuel stabilizer when storing.
7. For long-term storage, consider ethanol-free gasoline, which degrades more slowly.

Tools and parts

• Clear container for inspection

When to call a pro

A household hazardous waste facility can safely dispose of old gasoline you don't want to use.

Safety