Fuel Choice and the Hidden Costs

Fuel Choice and the Hidden Costs
Do I need premium fuel?

With the costs of fuel rising and falling, it raises questions of value. Does fuel choice really matter? Yes: in many of the performance-related engines (more often European class cars), premium fuel is required. In the non-performance-related engines, we can settle for the savings of a regular grade fuel choice. For optimum performance and fuel economy, choice should rest on the specifications and requirements of your particular automobile.

The first step in determining fuel choice is the “Owners Handbook” for your automobile. In the U.S. market, there are three grades of fuel: 87, 89, and 91 or higher octane. Octane is a measure of the characteristics in gasoline that determine the speed and duration of the flash/burn rate. The lower octane burns faster and a higher octane burns slower. How does octane and burn rate impact engine performance? How does this relate to your fuel needs? Below we will discuss the dynamics of fuel, and how to determine your fuel choice.

The compression ratio of your engine determines fuel requirements for optimum fuel economy, (mpg), and performance. Three components are required for proper combustion and performance: compression, fuel, and temperature. Low compression engines require fuel to burn quickly in order to complete the combustion cycle. A premium or high-octane fuel will take longer to reach a complete flash point in a low compression engine; subsequently the fuel may not burn completely. This could impact emissions and result in lost performance. A high compression engine requires a less volatile fuel with a slower flash point. A high compression engine operating on low-octane fuel will pre-ignite the fuel before the engine has reached maximum compression cycles. Under adverse conditions and high engine temperatures, the fuel may pre-ignite much sooner, well before the compression cycle is completed. This too may impact emissions, performance, and ultimately the life of the engine.

Price is not the only determinate of fuel choice. Understanding the dynamics of fuel choice and its relation to your car can greatly impact performance and reliability of your car. Factoring the costs difference of an incorrect choice may also help to recognize you actually are not saving much. Based upon the average of 12,000 miles driven per year, and an average of 25 miles per gallon, this adds up to very little in actual money costs/savings. Assume you are filling the tank 26 times per year, calculate the difference in mileage results using low octane rated fuel vs. high octane fuel and you will save about $1.00 per fill up. While it is arguable that you are saving money, what if you are causing your car to labor more and it results in premature wear or failure? What about the fact that you are producing more emissions? This is on the assumption of reducing fuel economy by 2 miles per gallon when selecting the lower octane, (less expensive) fuel. Are you really saving money? While it is difficult to place a value on the unknown damage you may be causing we strongly suggest you follow the Manufacturer’s recommendation in fuel grade, (octane) choice.