Bad Gas

A friend of mine on Facebook has a dilemma in relation to fuel storage: it seems he has about five gallons of gasoline that has been in a container for a year or two. He's been burning a bit of it at a time in his backyard fire pit, but unless you're aiming for a raging bonfire, that's real slow going. When he asked if there were any ways to consume it faster, it led to a great conversation.

Why is old gas a problem?

As petroleum fuels age, they begin to break down. Diesel fuel stays good for about a year, while gasoline starts to come apart at about six months. As they break down, their ability to burn degrades significantly, and they leave nasty deposits in engines. This can be prevented by using stabilizers and rotating fuel, as covered by Chaplain Tim here. Sticking to his advice means you'll always have fresh fuel to provide maximum power and efficiency in your engines.

What if your gas does go bad?

If your fuel does go bad, all is not lost; there are a couple things you can do to salvage it. If the fuel is in a tank already, the Seafoam product Tim mentioned does a wonderful job of "recovering" bad gas. I use it in my track car, because I ended up with half a tank of old gas that I thought had been drained. So far, it still makes good power and starts every time I hit the key.

If your fuel is in a gas can, the fix is even simpler: just dilute it with good gas. A ratio of 10:1 or better will burn just fine, and shouldn't harm an engine in good repair. Running a higher ratio like 15:1 will burn your bad fuel slower, but will burn easier in your engine, if you're worried. For clarification, that means 10 or 15 gallons of good gas to every 1 gallon of old fuel.

You can also run old fuel in gasoline yard tools, diluted with good fuel. The ratio can be a bit shorter in gasoline tools, as low as 5:1, since their engines are simpler with fewer places that can get gummed up and minimal electronics to be affected.


Prevention is always the best course. Rotate your fuel stocks and use fuel stabilizers whenever possible. If all else fails and you find yourself with some old gas, you haven't lost that money or that resource; hit it with fuel conditioner or dilute it with good fuel and carry on.

Lokidude