Almost every driver is familiar with octane ratings in gasoline. Octane's counterpart is cetane, related to diesel fuel, and it isn't as well-known by fuel consumers. Let’s look at what both octane and cetane numbers mean and how to use them to choose the right product.

Gasoline vs. Diesel Engines

Understanding octane and cetane numbers starts with understanding how fuel is ignited in an engine. In gasoline engines, gas and air are mixed, and then compressed and ignited. In diesel engines, the air is compressed before the fuel is injected.

Octane Numbers Explained

Octane is a hydrocarbon with low molecular weight. Its high flammability is one of the defining factors of gasoline effectiveness. The octane rating indicates the fuel’s resistance to combustion from pressure and heat. The higher the number, the less likely fuel will combust without the intentional spark.
The everyday representation of octane levels is the variety you see at our gas stations. For example, every Co-op Gas Bar offers three gasoline options: premium, mid-grade, and regular; each option is determined by its octane number. Regular and mid-grade fuels have lower levels of octane and premium fuel has high octane.

Cetane Numbers Explained

The cetane number is translated into the fuel’s readiness to ignite from the heat caused by air compression. The higher the number, the smaller the combustion delay, which is typically beneficial for diesel engines.

Octane and Cetane in Fuel Selection

Modern engines are designed to overcome octane and cetane sensitivity. With that said, choosing a high-octane fuel for gas engines and a high-cetane fuel for diesel engines can mean extended engine life and fuel economy, depending on the vehicle.
To choose the best product for your machinery, consult the owner’s manual to understand the manufacturer’s fuel recommendations. You can also reach out to a Saskatoon Co-op Fuel Team member for help finding the best fuel solution for your needs.