you can read more here on car and driver 's test of 5 different cars:

Regular or Premium?
Is premium fuel worth the premium price? Can you hurt a high-octane car by running it on the cheaper stuff?

http://www.caranddriver.com/xp/Caranddriver/features/2001/november/200111_feature_gasoline.xml

Pictures of my ride!!
'03 Vibe GT
My AED GA!
Work in progress

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Just wondering what grade of fuel everyone uses. I've been using premium (92 Octane), but I have friends that keep telling me to use regular.

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Just wondering what grade of fuel everyone uses. I've been using premium (92 Octane), but I have friends that keep telling me to use regular. Any advice or opinions???

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Definatly use the higher octane fuel. Most of todays cars are designed to run on 87 octane. But the higher compression design of the 2zz engine requires higher octane fuel to better control the combustion and ignition. When I picked up my new car it had 87 from the dealer. I noticed that the car pinged when I started out in first gear (I think pinging is pre-ignition?). After my first fill up (I noticed the warning the dealer must have missed) the pinging never re-occured. If pinging is pre-ignition it is bad for the engine. That would be exploding the fuel before it is fully compressed. This is bad on pistons and worse on connecting rods.

The car makers are not in bed with the oil companies and would not tell you to use higher octane without good reason

I know some of the prices are like $2.60 a gallon for regular...

As for the grade I use in my GT, I usually use 93-94 octane. I have used regular 87 octane before a few times and had no problems except that the "boost" of the engine over 6000 rpms was much less. I noticed the label inside the fuel door that said to use premium fuel shortly after I bought my car. On a trip back to the dealership a few days after I bought the Vibe, I asked my salesman about it since it had not been mentioned. He wasn't sure and made a few calls to some of the dealer's technitions (the dealer says that they are the largest GM dealer in North America, so I hope that they would have some people around who know what they are talking about). The answers that he got back were that running regular 87 gas in the Vibe GT would cause it NO HARM but would not allow the valve lift feature of the engine to give the full advertised horsepower. I didn't do the physical research myself, but like I said, I would think that these guys know what they are talking about. I usually use the higher octane in mine only because I am a total "balls to the wall" driver and want every last HP that my engine can muster at any given moment. If I drove like a little old lady, I'd use regular 87 almost all the time. If you have any doubts, call up the service department at a Pontiac dealer that you trust.

As for the car makers not being in bed with the oil companies, you have got to be kidding me. That has to be the single most lucrative lobbying effort going right now.

1998 GMC Yukon SLT 4X4, 151K miles, 4 door, two-tone white/gold, tan leather, loaded--my winter beast & Sopranomobile

Wanted: 2006 BMW X5 4.4i and 2005 BMW 750Li

Jim

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When I bought my GT, my saleslady told me to use regular 87 octane in and not to use plus or premium.

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I would call her back and let her know that it takes premium fuel only. My dealer did not know this either. I called him to confirm this when I read that the GT required premium here at Genvibe. At the time he though that it did take regular unleaded. He took a look at the manual and confirmed that it does require 91 octane or above. He was very glad that I let him know about it.

1998 GMC Yukon SLT 4X4, 151K miles, 4 door, two-tone white/gold, tan leather, loaded--my winter beast & Sopranomobile

Wanted: 2006 BMW X5 4.4i and 2005 BMW 750Li

1998 GMC Yukon SLT 4X4, 151K miles, 4 door, two-tone white/gold, tan leather, loaded--my winter beast & Sopranomobile

Wanted: 2006 BMW X5 4.4i and 2005 BMW 750Li

1998 GMC Yukon SLT 4X4, 151K miles, 4 door, two-tone white/gold, tan leather, loaded--my winter beast & Sopranomobile

Wanted: 2006 BMW X5 4.4i and 2005 BMW 750Li

My other question is why does the premium octain change but the Regular and plus stay the same?

I always use 91 octane in my Vibe GT

the gas price here is about $2.10 average.

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Premium is anything 91 or higher.

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Thanks Scott. I didn't know that anything 91 or above was premium. I guess it just depends on how high you want to go above 91 then.

I just think that it is funny the way there is such a big jump in octane where you live Nova. 87, 89, 93. you would think that if premium needs to be a higher octane then the other grades would follow suit. Example 89, 91, 93 for Regular, plus and premium. But they want to make money. Out of curiosity how much is 93 octane? 91 currently ranges from about 1.69 to 2.09 here.

This also brings up the question of how they do it. I co-oped for BP in Lima (at the chemical plant) and since all our electric came from the Refinery I interacted with them alot. I questioned one of the engineers there after I saw a Shell, bp, speedway, and a Clark truck all picking up gas at the Premcor terminal. He told me that all gas is the same, just different companies put different additives in it.

The refinery (doesn't matter Exxon, Shell, etc) produces various grades of fuel - 89, 91...
Each downstream retailer creates an additive package and supplies it to the terminal.
When the delivery trucks lift the fuel, they key in a code that indicates for whom they are lifting the fuel... this code alerts the pumps to inject the appropriate amount of the appropriate company's additive. The type and amount of additive is the only real difference between fuels.
HOWEVER, some refineries are not set up to produce a 93 octane product so you have to have a 'high octane' refinery somewhere near you to get the rocket fuel.

Some independent stations simply purchase, for example, Shell fuel. I'm not sure if they get the full Shell additive package or some lesser form thereof but that's how independant stations get their product.

One other point... in Canada, at least, it's legal to sell 93 as 89 but not 89 as 93 thus there is the potential that you'll get something better than 89 when you purchase reg while a low volume 93 may actually degrade over time to less than 93. Those of us with Base Vibes... 89 is the best value and we'll not really notice any performance or mileage difference.