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I have a question for the masses.

On this site as well as others, I always see people asking about how their car which recommends high octane fuel (91) runs on regular grade (87) fuel. My question is why?

Specifically, why spend $20,000-$25,000 on a new sports car, pay a premium in insurance because it is a sports car, pay a premium on tires because it likely uses rather large tires, possibly with a short lifespan, and then use a lower grade fuel which will cause a loss of power and in more extreme situations possibly cause engine damage, just to save about $120 a year?

(say you get 20 MPG, drive 12,000 a year. That is 600 gallons. Premium usually costs $.20 more per gallon than regular. Therefore, the additional cost would be $120 per year, $12 per month, or $.32 per day).

It just doesn't seem to make much sense to me, since premium gas really doesn't cost that much more per tank. Especially when compared to all the other expenses of owning an automobile.
 

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I couldn't answer that, I use premium always in the MSM.

On the MSM board,they had a discussion: due to gas shortages from H. Katrina, premium was at a premium (not avalaible), they chose to carry octane boost to protect the engine should they get stuck with lower octane gas.

p.s. the MSM manual calls for premium.
 

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I have a friend in the Oil Company (gasoline selling business) and he swears up and down and around and around that premium gas for most vehicles is hype, pure hype.

According to him, at the same gas station, the premium gas itself isn't any better, as a matter of fact, the gas itself is exactly the same for all 3 grades. Premium just has more octane additive in it which makes it burn faster & hotter. Faster burning is what might give certain cars a little more pep, and hotter might help make sure everything burns so less deposits are left behind. Better gas milage claims are mostly bogus. But burning gas faster & hotter is not always best, and may actually harm some engines.

According to him, where gas quality can differ is from brand to brand, and even store to store. According to him brands like Mobil and Texaco have better gas than say Speedway. And one Mobil store in town might have a better means of keeping their tanks, pumps and nossels cleaner than the other Mobil store, especially if the owners are different.

Many small engine devices like lawn mowers, chain saws, and weed whackers etc. tell you NOT to use premium because it makes them burn too hot. This I've seen for myself.

But, just to prove I'm not 110% sure of my friend, I've bought premium in my cars since 1997. My wife on the other hand has bought only regular, and she's up to about 120,000 miles. I personally don't think it makes a whole lot of difference in normal everyday cars and driving conditions. Changing your oil regularly is far more important.
 

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Bonzo said:
I have a friend in the Oil Company (gasoline selling business) and he swears up and down and around and around that premium gas for most vehicles is hype, pure hype.

According to him, at the same gas station, the premium gas itself isn't any better, as a matter of fact, the gas itself is exactly the same for all 3 grades. Premium just has more octane additive in it which makes it burn faster & hotter. Faster burning is what might give certain cars a little more pep, and hotter might help make sure everything burns so less deposits are left behind. Better gas milage claims are mostly bogus. But burning gas faster & hotter is not always best, and may actually harm some engines.

According to him, where gas quality can differ is from brand to brand, and even store to store. According to him brands like Mobil and Texaco have better gas than say Speedway. And one Mobil store in town might have a better means of keeping their tanks, pumps and nossels cleaner than the other Mobil store, especially if the owners are different.

Many small engine devices like lawn mowers, chain saws, and weed whackers etc. tell you NOT to use premium because it makes them burn too hot. This I've seen for myself.

But, just to prove I'm not 110% sure of my friend, I've bought premium in my cars since 1997. My wife on the other hand has bought only regular, and she's up to about 120,000 miles. I personally don't think it makes a whole lot of difference in normal everyday cars and driving conditions. Changing your oil regularly is far more important.
And many of today's engines can auto-adjust for octane - advancing timing and obtaining more torque if you use premium - EVEN if they don't say it in the owner's manual. It isn't hype if your car is able to do so - you DO get more performance for 91 Octane, especially if your car has it as an option (like the Solstice). I've also talked with people who work on Ford motors, and some of their engines do similar strategies as Honda and presumably the ecotec - tweak the timing forward as far as the octane allows.

As far as octane, BY LAW, when you buy a fuel with a specified octane, it MUST be that octane or better. You are getting a true benefit for your extra $0.20 per gallon - fuel that is less prone to autoignition. And with today's engines, you may actually be able to use it.

As always, there is never a simple answer to simple questions.

For the Solstice - buy 91 or higher octane. It's less than 3 Starbuck's Grande Lattes a month... or a third of a cable bill... or half of most people's telecommunication bill........
 

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I believe a lot of the debate is due to the fact that GM was always claiming that the Solstice would only require regular gas, then a few forum members got ahold of the owner's manual, which specified premium (91 octane). So the question arose, what changed about the engine that it now requires premium? Or did GM add the premium requirement for the sole purpose of getting the horsepower increase that we've also seen, where the hp number jumped from 170 to 177 hp ?

If the change to premium gas was solely for the purpose of gaining those 7 extra horses, and you personally don't feel the car is underpowered at 170, then why would you pay extra for gas when you don't see the benefit?
 

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Bonzo said:
I have a friend in the Oil Company (gasoline selling business) and he swears up and down and around and around that premium gas for most vehicles is hype, pure hype.
True. Being setup to use premium, the Solstice is an exception.

Bonzo said:
According to him, at the same gas station, the premium gas itself isn't any better, as a matter of fact, the gas itself is exactly the same for all 3 grades.
This should be tested randomly as part of maintaining certification. They could technically sell 92 octane gas as 87/89/92, but they wouldn't since it does indeed cost more to make higher octanes.
Bonzo said:
Premium just has more octane additive in it which makes it burn faster & hotter. Faster burning is what might give certain cars a little more pep, and hotter might help make sure everything burns so less deposits are left behind.
Actually, premium burns slower and is less volatile (harder to ignite). Octane value (or AKI, Anti-Knock Index) indicates how well a fuel holds up to pre-ignition. This is why using premium will "cure" knock in an aging engine covered in carbon deposits.

Bonzo said:
According to him, where gas quality can differ is from brand to brand, and even store to store. According to him brands like Mobil and Texaco have better gas than say Speedway. And one Mobil store in town might have a better means of keeping their tanks, pumps and nossels cleaner than the other Mobil store, especially if the owners are different.
Yup, brands very greatly when you look at what detergents and other additives are in there.
 

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solsticeman said:
And many of today's engines can auto-adjust for octane - advancing timing and obtaining more torque if you use premium - EVEN if they don't say it in the owner's manual......especially if your car has it as an option (like the Solstice).....with today's engines, you may actually be able to use it .....
So how do you know if your car has this "auto-adjust" thing without spending hours trying to find out. I have a 2004 Nissan Murano and my wife has a 1997 Grand Am. Is it fair to say something as basic as, FOR EXAMPLE, prior to to 1999 no engines had this "auto-adjust," between 1999-2001 only Honda had this, and after that you need to check your manual?

Sounds like my friend might be slightly behind the times of automobile engines, but up until just recently he was/is basically right. And he may even still be right depending on what kind of engine you have, especially older engines and cars with lower compression ratios.
 

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Chris said:
Actually, premium burns slower and is less volatile (harder to ignite). Octane value (or AKI, Anti-Knock Index) indicates how well a fuel holds up to pre-ignition. This is why using premium will "cure" knock in an aging engine covered in carbon deposits.
Maybe I had this part backwards. Sorry. I have to say I've never listened with 100% concentration when someone is rambling on about gas types or prices etc. When my Mom starts talking about getting gas a penny cheaper 5 miles down the road I zone out.

One thing is for sure, there sure is a lot of MIS-INFORMATION out there in the general public about gas and how it affects engines.
 

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Bonzo said:
Sounds like my friend might be slightly behind the times of automobile engines, but up until just recently he was/is basically right. And he may even still be right depending on what kind of engine you have, especially older engines and cars with lower compression ratios.
Sounds about right. Before computer controlled timing adjustments, running premium in a car tuned for regular would get you nothing and could actually hurt performance since the fuel is harder to ignite. In the opposite situation, running regular in a car expecting premium (FI, high compression, whatever) could cause serious damage because of all the pre-ignition. Everything is much more forgiving these days.
 

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Bonzo said:
One thing is for sure, there sure is a lot of MIS-INFORMATION out there in the general public about gas and how it affects engines.
Yup, engines have changed a lot over the years and so have the rules. A lot of the "bad info" is really just "outdated info".
 

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Well, Lori queen says it runs fine on regular, I'm not concerned about high performance (if I was, I would have waited for the turbo) so why not save a couple hundred every year?
 

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Editguy said:
Well, Lori queen says it runs fine on regular, I'm not concerned about high performance (if I was, I would have waited for the turbo) so why not save a couple hundred every year?
:banghead:
I'm with ya Fformula, I just don't get it.
 

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Chris said:
:banghead:
I'm with ya Fformula, I just don't get it.
What don't you get? Saving money? If they said that it would damage the engine, of course I wouldn't use regular. But Lori Queen said that most drivers would never even notice the difference, that using regular was no problem. So why spend the extra money? I'm not buying this car for performance, if I was I would have looked for a used Vette, or waited for the turbo. And I will be driving about 30k miles a year, so it will add up. But if a few hundred dollars is meaningless to you, PM me and I will tell you where to send the checks. :D
 

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Editguy said:
What don't you get? Saving money? If they said that it would damage the engine, of course I wouldn't use regular. But Lori Queen said that most drivers would never even notice the difference, that using regular was no problem. So why spend the extra money? I'm not buying this car for performance, if I was I would have looked for a used Vette, or waited for the turbo. And I will be driving about 30k miles a year, so it will add up. But if a few hundred dollars is meaningless to you, PM me and I will tell you where to send the checks. :D
:lurk: crunch... crunch... crunch...
 

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Editguy said:
What don't you get? Saving money? If they said that it would damage the engine, of course I wouldn't use regular. But Lori Queen said that most drivers would never even notice the difference, that using regular was no problem. So why spend the extra money? I'm not buying this car for performance, if I was I would have looked for a used Vette, or waited for the turbo. And I will be driving about 30k miles a year, so it will add up. But if a few hundred dollars is meaningless to you, PM me and I will tell you where to send the checks. :D
Actually, I have the manual, and it does state that the car requires 87 octane. I think it might recommend 91 for better performance. I'll have to check it when I get home for the exact wording.

Flagg
 

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Here is a quote from the April 2005 issue of Consumer Reports:

"Myth: If regular-grade fuel is good, premium must be better.

Reality: Most vehicles are designed to run just fine on regular-grade (87 octane) fuel. A higher octane number doesn't mean that your vehicle will perform better. It simply means that it's more resistant to engine knocking or pinging. Use the octane grade that's recommended in your vehicle's owner's manual. Filling up with a higher grade is usually a waste of money. "


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Higher octane is designed for higher compression engines and older engines that have built up deposits that require the fuel to burn hotter to prevent knocking.

Flagg
 

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Editguy said:
What don't you get? Saving money? If they said that it would damage the engine, of course I wouldn't use regular. But Lori Queen said that most drivers would never even notice the difference, that using regular was no problem. So why spend the extra money? I'm not buying this car for performance, if I was I would have looked for a used Vette, or waited for the turbo. And I will be driving about 30k miles a year, so it will add up. But if a few hundred dollars is meaningless to you, PM me and I will tell you where to send the checks. :D
I guess to me it boils down to the fact that the engineers designed a car for premium, so give it premium. Your car's gunna be running in "WARNING: LOW OCTANE - RETARD TIMING" mode all the time. This is abnormal and requires corrective action. It's a bad analogy, but to me it's almost like ignoring an engine light just because you know the problem won't make the car explode.
 
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