Best first post ever!Very Informative Excerpts. Check the American Petroleum Institute (API) for more information.
THE FACTS ON HIGH OCTANE GASOLINE
* Do you buy a high octane gasoline for your car because you want to improve its performance? *
The recommended gasoline for most cars is regular octane. In most cases, using a higher octane gasoline than your owner’s manual recommends offers absolutely no benefit. It won’t make your car perform better, go faster, get better mileage or run cleaner. Your best bet: listen to your owner’s manual.
* Does high octane gasoline increase power? *
If your car is designed to run on 87 octane gasoline, you shouldn't notice any more power on high octane gasoline. If it does make a noticeable difference, you may need a tune-up.
* Does high octane gasoline improve mileage? *
In general, if your car is designed to run on 87 octane gasoline, high octane gasoline will not improve mileage. If switching to high octane gasoline does improve mileage, you might find that a tune-up will give you the same improvement on 87 octane gasoline.
* Does high octane gasoline achieve quicker starting? *
No, it doesn't.
* Will higher octane gasoline clean your engine better? *
As a rule, high octane gasoline does not outperform regular octane in preventing engine deposits from forming, in removing them, or in cleaning your car’s engine. In fact, the U.S. Environmental Protection Agency requires that all octane grades of all brands of gasoline contain engine cleaning detergent additives to protect against the build-up of harmful levels of engine deposits during the expected life of your car.
* Is high octane gasoline more refined -- is it just a better product? *
Additional refining steps are used to increase the octane; however, these additional steps do not make the gasoline any cleaner or better. They just yield a different blend of hydrocarbons that burn more slowly. The additional steps also increase the price.
* What are octane ratings? *
Octane ratings measure a gasoline’s ability to resist engine knock, a rattling or pinging sound that results from premature ignition of the compressed fuel-air mixture in one or more cylinders. Most gas stations offer three octane grades: regular (usually 87 octane), mid-grade (usually 89 octane) and premium (usually 92 or 93). The ratings must be posted on bright yellow stickers on each gasoline pump.
* What’s the right octane level for your car? *
Check your owner’s manual to determine the right octane level for your car. Regular octane is recommended for most cars. However, some cars with high compression engines, like sports cars, old cars and certain luxury cars, need mid-grade or premium gasoline to prevent knock.
How can you tell if you’re using the right octane level?
Listen to your car’s engine. If it doesn’t knock when you use the recommended octane, you’re using the right grade of gasoline. Knock occurs when cylinder pressures are high. It is normal for an engine to ping a little at full throttle because cylinder pressures are very high at full throttle. Engine knock, however, should not be ignored since it can result in serious damage to the engine. High octane gasoline burns slower than low octane gasoline. The slow burn prevents engine knock when cylinder pressures are high.
If your engine runs well and does not knock or ping on low octane gasoline, there is no advantage in switching to higher octane gasoline.