Go to nearly any American gas station and you’ll see that there are different octane ratings. Apart from diesel, you will find typically three octanes (87, 89 and 92), but numerous people do not know what’s best for their car. Reading your vehicle’s manual helps, but have you ever wondered why one octane is better for car than an additional? As outlined by About.com, there are a number of things to consider, so enjoy the following summary.
What is the octane rating?
A gasoline’s octane rating measures the degree of resistance to knocking. A knocking sound occurs when your internal-combustion engine’s gasoline-air mix ignites prematurely instead of burning smoothly and efficiently. The octane rating is determined after a gasoline is compared to isooctane and heptane. Isooctane has a “perfect” 100 octane rating, while heptane sits at the low end, namely zero. According to About.com, untouched gasoline has an octane rating of about 70 (70 percent isooctane, 30 percent heptane). Adding lead to gasoline used to be the common way of combating knocks and pings, but that was replaced by unleaded gas with more expensive anti-knocking compounds.
Is it as simple as using higher octane gas?
Older car engines depended upon the carburetor to control the air/gasoline mix, so higher octane rating gas was helpful. As engines became more complex, electronic fuel injectors took over the fuel mix work of the carburetor. Subsequently, 87 octane became the American standard for most vehicles. This enabled efficient function without overwhelming the emissions system.
And what of mid-grade gasoline?
Understanding octane rating standards within the U.S. is essential here. There isn’t a clear delineation between 87/89/92 octane ratings and gasoline grades; the categorization varies from state to state. One state might require a minimum octane rating of 92 for premium, while another might allow 90. Check your owner’s manual and watch for the octane rating on the yellow sticker at the pump.
What about premium gasoline?
If this is the case, you probably have a high-performance engine under the hood. These engines are ultra-efficient and avoid passing unused fuel into emissions and the catalytic converter, which would produce a distinctive egg-like smell. On a related note, some big cities with air pollution difficulties may require that vehicles use special reformulated gasoline. Clean-burning comes from oxygen infusion with this special formulation. Just don’t drive with too little fuel within the tank; that’s muck up the valves and filters. It’ll ruin your car’s day.
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http://chemistry.about.com/od/chemistryarticles/a/which-gasoline-to-buy.htm
