What Happens to a Car If Bad Gas Is Put in It?

Fueling up.

Bad gas can cause immediate performance problems and, in some cases, permanent damage to your engine. It may cause your car not to start. What it does to your car depends on what is wrong with the gas.

Dirty Gas

Gas containing debris, such as dirt or rust, will clog your fuel filter. It also can damage your fuel pump. When the fuel filter gets dirty, fuel delivery is limited or blocked. The car will act like it is out of gas or running out of gas.

Old Gas

Gasoline that sits too long will go bad, lose its volatility. It eventually turns into a varnish that will coat your gas tank, fuel lines and carburetor or fuel injectors. If you run the engine after this happens it can cause serious engine damage. The varnish in your gas tank can dry up and flake off creating debris in the gas.

Low Octane

Low octane causes combustion problems that make the engine knock or ping. It can also cause the engine to keep running briefly after you shut off the ignition. Check your owner's manual for the correct octane rating for your car.

References

• aa1car: Bad Gasoline Causes Performance Problems
• Sterndrives: My Carburetor Smells Like Varnish
• Performance Oil Technology; Beware of Bad Gasoline- Tech Talk
• MGAguru: Engine Run-On, Dieseling