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Octane Ratings – Premium vs Regular Gas: What’s The Difference?

Posted in Car Tech, Fuel, Gas Prices, Guide by Vito Rispo | October 15th, 2008 | 6 Responses |

There are a number of myths about the octane ratings of gasoline. In actuality, octane ratings only tell you one thing: the amount of resistance to detonation the gas has. But what does that mean?

That just means that gas with a higher octane is less likely to detonate before the spark plugs fire. Sometimes gas does that, like if your car’s engine has a particularly high compression ratio, the fuel/air mixture in the cylinder will get compressed so much that it may just combust, without any spark. That type of premature detonation, is called “knocking”. Sounds filthy right? It is.

Knocking can do some damage to your engine. It gets the engine working against itself, and can cause all sorts of problems. The thing is, it’s not going to happen for more than a second or so. All modern cars have a “knock sensor”, which is a little microphone that senses the actual sound of the knock and adjusts your compression and fuel mixture to stop the knock.

Most cars get absolutely no benefit from premium gasoline AT ALL, but some high performance cars have a higher compression ratio, and they can benefit from it. But they don’t need it. Because of the modern knock sensors, even high performance cars with high compression ratios don’t need premium gas. You won’t get the maximum amount of power from the high performance car if you use regular, but you’re not going to damage your car.

So the bottom line is: premium gas, for 90% of all drivers, is a complete waste of money, with zero benefits. For the small percentage of people who have high performance/high compression cars, premium gas will help you squeeze out that top shelf performance, although it’d be difficult to feel a difference.

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6 Responses

  1. […] Re: 93 octane or not Nice article took me a few minutes to understand it but makes since! Octane Ratings – Premium vs Regular Gas: What’s The Difference? […]

  2. […] 93 octane or not Nice article took me a few minutes to understand it but makes since! Octane Ratings – Premium vs Regular Gas: What’s The Difference? I say NOT unless your engine is tuned to burn it ! Last edited by HOGWILD; Today at 05:44 […]

  3. mitch says:

    i have 98 is that better than all the rest?

  4. todd says:

    I disagree with this article. At the local Shell 87 octane is 10% alcohol and 89 is 5% and 91 is zero methanol.

    You will get more power and more mileage out of a gas with 10% more gas in it. Methanol does not have the same power per liter as gasoline.

    However the oil companies are charging as much as 20 cents a liter more for the V Power premium so for a miles per dollar basis you are coming out behind. But on a miles per tank you are coming out ahead. It really depends on what the extra cost is.

  5. scott says:

    I go to Colorado every year and their regular gasoline is only 85 octane which is not even sold in Kansas. Seems to me that 85 would not be good in the mountains so i always use the 87 octane which is considerably more expensive. I once used the 85 by accident in my T bird and it pinged terribly. HOW DO THE COLORADO PEOPLE GET BY WITH USING 85 OCTANE AND WHY IS THIS SOLD ALL OVER COLORADO?? THANKS FOR THE INFOR

  6. Adam Cunningham says:

    on my 2004 Navigator calls for 91+ i started using 89 it started to sputter ,and by the 3rd tank it stalled i had to get all coils replaced