As gas turns bad it darkens, eventually turning a deep amber color. Empty cans and tanks often contain old gas deposits. When new gas is added, these deposits break loose, clogging the fuel line ...

Bad gasoline has a definite aroma on a par with old varnish. It is extremely pungent and has a horrid smell. It is also darker in color, turning brown and sometimes green if it’s really old.

There are a few different colors of diesel fuel, and each one has a specific purpose. Here's what it should look like ...

In addition, Kohlman inspected the color of the gas. It should be clear and bright with no signs of haziness. The test Contact 6 witnessed at a gas station in Oak Creek showed no signs of water ...