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Octane has to do with compression and nothing else. Simply put higher octane will not explode prematurely when it is compressed a lot. If the car is not high compression, it does not need high octane and will not benefit from it. Contrary to many urban myths higher octane gas does not burn hotter, cleaner, or with more power. You will not get better mileage with it. It will not clean out your engine. Higher octane gas is not "more explosive" In fact, it is more stable (e.g. less explosive). If your car does not require higher octane, your car will get no benefit whatsoever from putting higher octane gas in your tank.
The funny thing is that more people believe the urban myths than really know what octane means. If you were to ask 50 people, probably 40 of them would think it burns hotter, cleaner and/or makes an engine more powerful. Hardly anyone seems to understand what Octane really means. Try it, ask a half dozen people.
Octane has to do with compression and nothing else. Simply put higher octane will not explode prematurely when it is compressed a lot. If the car is not high compression, it does not need high octane and will not benefit from it. Contrary to many urban myths higher octane gas does not burn hotter, cleaner, or with more power. You will not get better mileage with it. It will not clean out your engine. Higher octane gas is not "more explosive" In fact, it is more stable (e.g. less explosive). If your car does not require higher octane, your car will get no benefit whatsoever from putting higher octane gas in your tank.
The funny thing is that more people believe the urban myths than really know what octane means. If you were to ask 50 people, probably 40 of them would think it burns hotter, cleaner and/or makes an engine more powerful. Hardly anyone seems to understand what Octane really means. Try it, ask a half dozen people.
While I generally agree with this...
There is an additional benefit of Premium fuel using high concentrations of detergents and fuel system cleaners.
This alone can make the price difference justifiable.
What cars generally use premium or Supreme gas and Plus or medium grade?
Cars with high-compression engines, superchargers, and turbochargers tend to be the ones that require 91+ octane premium fuel. A small handful of engines state they require 89-octane mid-grade to produce full power, such as the Dodge Hemi engine (can run on 87 regular, but won't make full power unless given 89+ octane.) Everything else uses regular 87 octane.
One side note: mid-grade gasoline in many places in the Midwest is 10% ethanol and regular is no ethanol. The 10% ethanol stuff is less expensive than the no-ethanol stuff so most people put mid-grade into vehicles that specify regular. You will not hurt an engine by giving it fuel with a higher than required octane, but you can hurt an engine that requires higher-octane fuel by giving it lower-octane fuel. You won't get any benefit from giving an engine higher than required octane in many cases though*
*Read your owner's manual! Some newer engines actually require 89-91+ octane fuel to make full power but will automatically retard timing (making less power) to run safely on 87 octane regular. So in those cases, you won't hurt your engine by running 87 but you WILL get a benefit from running a higher octane. The new 5.0 L Ford V8 in the Mustang and F-150 is one of these engines, it makes about 15 more HP on premium than regular but will run safely on either.
Keep in mind that octane ratings (recently AKI indexes which is an average octane) vary across the country with various areas having lower octane fuel (often higher altitude with old agreements about what is appropriate in the area) and some with higher octane available. Also keep in mind that fuel changes with seasons in many areas to control volatility in temperature swings).
Unleaded gasoline across the country today will vary from 85 octane to 94 octane, most with 10% ethanol but some without.
Your best bet 99% of the time is to simply use the octane rating (or higher) recommended by the auto manufacturer.
Coldjensens wins the thread! I want to quote his post for future use on a couple of other forums!
I just learned this recently when someone mentioned it on CD, so I did some research. I was surprised. For about 30 years I thought that Octane had something to do with burning hotter, cleaner or producing more power. I thought that high octane gas would help clean out the engine and/or make a car run better or faster or get better mileage. As a teen I dumped many bottles of 103 plus into my 1973 Camaro gas tank thinking it would make it go faster.
Can I have that money back please?
Some brands do add a bit more detergent to the high octane gas, but nothing that makes any difference. The lower octane gas is nto sold with a detergent blend designed to be insufficient.
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