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Discussion Starter · #1 ·
I see everyone is affected by the gas hike and I have a question about the grade of gas to use. I use premium right now for my 02 GTI 1.8T and I drive back and forth from south jersey to NYC every week!!! Costing some serious cash, especially with the price hike. Here is my question, Would there any harm to use regular gas in my car? Instead of the premium gas I use now. I haven't switch yet but tempted.
 

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Re: Gas question! (bigaGTI)

This is not advised. The sole difference between the different grades of gas (contrary to what advertisers hope you will think) is the level of octane (a hydrocarbon). The presence of octane changes the way the fuel burns and reduces the occurrence of premature detonation, also known as knocking. Knocking causes damage to the walls of the cylinders in the engine which builds up over time. Some vehicles have knock sensors in their engines which can detect this, and will retard your engine's timing to make up for the increased premature detonation so that damage will be reduced.
For any vehicle, the required octane level is printed in the owner's manual or inside the fuel filler cap. Follow the manufacturer's recommendation for octane levels -- using lower than recommended octane fuel will damage your engine. Using higher-grade fuel than required will not give you any more power or better mileage.
For the 1.8T engine, the recommended octane level is 91. Stick with it.
 

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Re: Gas question! (bigaGTI)

From what I've read for a turbo the higher octane is mandatory. I ran regular in VR6 for a while and it never knocked but with the fuel trim CEL problems I had I just got paranoid
and started using premium. Some people say premium's a waste of money and tunless you drive a huge muscle car or something the average car releases the extra octane as exhaust. Others (like a mechanic I know) says if your car calls for it, put it in.
Right now I'm taking following VW's instructions. And feeling the sting to the wallet.
 

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Discussion Starter · #4 ·
Re: Gas question! (Buran)

Wow,
I didn't read the manual. I didn't know the recommended octane is 91. Good. I am using 93 octane. So I can save alittle. Feeling the sting every weekend when I drive up to NYC!
 

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Re: Gas question! (bigaGTI)

I know I might get flamed for this but, what about using a lower grade fuel and then using an octane booster?
 

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Re: Gas question! (goosmn)

Just use the lower grade. Our cars are equipped with knock sensors. If the gas creates knock, the sensor will pick it up and retard the timing. The only thing that will happen is you'll lose a couple of horsepower.
Just realize that it will take at least a tank or two for the ignition to fully advance to optimum range after you start using premium again.
 

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Re: Gas question! (Rare Hare)

Your car will be slower (think like 20 hp slower), but it'll run just fine. Since you have a knock sensor, your ECU will pull timing.
Seriously, it saves me about $600 a year, and I drive 600 miles a week. Is it that big of a deal?
 
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