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Old 11-16-07, 12:12   #33 (permalink)
Aurora40
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Re: Premium gas? Facts & Myths

Quote:
Originally Posted by 32VDOHC
Pre ignition which is the cause of the knocking sound in a engine under a strain, does not happen while using premium fuel. This pre ignition reduces power and fuel mileage.
If the car does not call for it, consider yourself lucky.
Pre-ignition happens when the fuel ignites on it's own before the spark fires. This is pretty much catastrophic to an engine.

That is not the light pinging sound that some engines make, that is called detonation. Newer cars with sensitive knock sensors, they can detect such small detonation and adjust that you'd likely never hear it at all.

My two cents. You need how much octane you need. More is a waste. If you want to find out how much you need, put some gas in the tank, hook up a scan tool, and go drive the car hard. If there is no knock retard, you don't need more octane. If there is, maybe you do. If you don't care about wasting it, put in premium and enjoy.

If you want to keep your engine clean, as said, use a Top Tier gasoline. This way you know that even the lesser octanes still have an acceptable amount of additives in them to keep your fuel system clean.

I often put in 87 octane when going on long trips because I can burn through a tank or two without ever going to wide-open throttle. Even an engine that needs more octane doesn't need it at low throttle operation.
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