High octane sounds like a good thing. Those pleasant-sounding words could account for a large portion of premium unleaded gasoline sales. High octane also costs more. Some drivers who buy high octane gasoline think they cannot go wrong. After all, the term high octane sounds cool. Also, the high price for premium unleaded must mean that high-octane gasoline offers advantages over regular unleaded. Right? Not necessarily. Confusion about octane has led many consumers to ask questions about why octane matters.
About Octane
Scientists know octane as a hydrocarbon found in petroleum. As a liquid, octane comes in numerous, distinct forms. Gasoline, a petroleum product, contains octane and helps define its characteristics. The octane rating of gasoline differentiates the several different options motorists have when they fuel their gasoline-powered vehicles.
Octane at the Pump
Motorists have grown accustomed to seeing three grades of gasoline available when they fill up their cars: Unleaded Regular (usually 87-octane), Unleaded Plus (usually 89-octane) and unleaded premium (normally 91-octane). High-octane fuel usually costs more than low-octane fuel.
Drivers have long felt emotional conflicts while fueling vehicles because they perceive high-octane gasoline as high-quality, but the extra cost pushes them to buy low-octane gasoline that they perceive as having low quality. Some drivers resolve this conflict by fueling their cars with mid-grade gasoline which comprises a blend of high- and low-octane fuels.
Octane and Knocking
High-performance car engines increase their power by using a high compression ratio. Unfortunately, the high compression found in these engines causes low-octane gasoline to ignite before the spark plugs can ignite it. Knocking results. Although most high-compression-ratio engines have internal mechanisms that control knock, many experts suggest that too much engine knock can cause premature engine wear and degrade overall engine performance. Automakers solve the engine-knock problem in the high-performance engines they make by calling for the use of high-octane gasoline. High-octane gasoline withstands high-compression ratios, so it only ignites from engine spark plugs. This allows performance engines to deliver their intended levels of horsepower.
Read the Owner’s Manual
The U.S. Federal Trade Commission says that cars can only benefit from the use of high-octane fuel if the manufacturer calls for its use. Therefore, drivers who want to know what kind of gasoline they should put in their cars should read the owner’s manuals that came with their cars. Cars equipped with engines that were designed to run on regular unleaded (low-octane) gasoline will not run better on high-octane gasoline. However, cars equipped with engines that were designed to run on premium unleaded (high-octane) gasoline will perform better, make more power available to drivers and eliminate potentially damaging engine knock. Drivers who do not have the owner’s manual that came with their cars should either call or visit their dealers to find out what kind of fuel to use.
Why Buy Mid-Grade Gas?
Automakers build some cars designed for mid-grade fuel. Some filling stations that operate in high elevations above sea level sell 89-octane gasoline as unleaded regular. Drivers should only buy gasoline labeled as unleaded plus if the owner’s manuals for their cars call for its use. Vehicle owners should address any questions to the Sears Imported Autos service team.
