Gasoline Octane Ratings

At a time when it is so important to get the most out of our money we need to understand gasoline octane ratings and how they can effect our wallets!

Since the mid 80’s engines have used fuel injectors with computers to accurately control their air/fuel mix.  The accuracy of the fuel injectors and computers is based on using the proper gasoline for that engine.  The difference in the name and price of the fuel is based on the gasoline’s “octane”.   To determine a gasoline’s octane rating, it is subjected to two testing methods, the motor method and the research method.  The motor method runs the gasoline in an engine running under load and the research method runs the gasoline in a free-running engine.  The octane rating is an average of  the two tests.

Regular gasoline has an octane rating of at least 87.  The octane rating of ” Mid-grade” gasoline ranges from 88 to 90.  “Premium” gasoline rating can vary depending on the state where it is purchased but must be higher than 90 in most states.

The octane rating tells you how much the fuel can be compressed before it spontaneously ignites.  When gas ignites by compression rather than because of the spark from the spark plug, it causes knocking in the engine.  Simply put, the octane rating of gasoline is a measure of its resistance to knock.

Most cars today are designed to run on Regular  87 octane gasoline, but it’s important to check your owner’s manual so you know that you are using the level of octane the manufacturer recommends for your vehicle.  Some people think if you put a higher octane gasoline in your car, you can increase the engine’s power or get better mileage.  This is a myth.  If your car is designed to run on 87 octane, high octane gasoline won’t improve mileage or increase your car’s power.  If your engine runs well and doesn’t knock or ping on low octane gasoline, there isn’t an advantage in switching to a higher octane gasoline.  So save your money at the pump and don’t pay premium prices for something that your car doesn’t need!

 

For all of your Denver Auto Repair needs, trust Express Car Care. Call (303) 691-2760 or stop by our shop today.