Octane question

87 is recommended for my 89 Crown Vic 5.0. Will using 89 or 93 be beneficial? Car has 81,00 miles. TIA! Bob Manly/Orlando

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The octane rating is the number given for the resistance of the gasoline to ignite. The higher the rating, the harder it is for the gasoline to burn. Your engine may knock if you are using a lower octane rating than is recommended by the manufacturer. Also, as an engine ages carbon tends to build up within the combustion chamber to the point that it increases the compression ratio. Therefore, older engines sometimes have a tendency to knock when burning the recommended fuel octane. The reason for the knocking is that the fuel/air mixture is igniting too EARLY. Engines are designed (compression ratio/timing) for a specific octane rating - it is usually a BIG waste of money to use a higher than recommended octane rated fuel.
Therefore, the easiest answer to your question regarding the proper octane fuel to use is to use the octane rating as close as possible to what the manufacturer suggests for the engine. This mindset assumes you have not made major modifications to the engine (compression ratio/timing).
Yet another $.02 worth from a proud owner of a 1970 Mach 1 351C (searches for the highest octane I can find) @ http://community.webshots.com/album/18644819fHAehGJAjt

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The higher the octane, the slower the mix burns. Using a higher octane fuel than your engine requires will cause it to have less power, (since the fuel never really burns correctly) and will contribute to carbon buildup.
High octane fuel is designed for higher compression engines, which can burn the mix effectively.
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Yeah, it helps the gas companies. They make more money.
Unless your engine knocks with the lower octane gas, use it. BTW, using a lower octane gas is probably good for the environment, too, because it takes less refining to make to it (and less refining means less energy used in refining it, I think).
Jeff
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