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Fuel requirement, again, maybe...

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  #1  
Old 03-20-2012 | 09:28 PM
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Default Fuel requirement, again, maybe...

Been away for awhile; thought I'd return for a question.
We had the A4 2.0T in for state inspection today, and in gabbing with a salesman, he remarked that he ran his car on 89 with no ill effects.
There is a .20 @ gal bump to 91 in our area, which isn't inconsequential (what, $3 for a fillup?), but it does add up over time.

Did a search here; best I found was a thread from 2005, so I'll ask what the current thinking is.

Any harm in running the 2.0T on midgrade (89 octane) fuel? Does it degrade performance by retarding the timing? Any other thoughts?
Thnx,
Moon
 
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Old 03-21-2012 | 06:51 AM
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Originally Posted by halfmoonclip
Been away for awhile; thought I'd return for a question.
We had the A4 2.0T in for state inspection today, and in gabbing with a salesman, he remarked that he ran his car on 89 with no ill effects.
There is a .20 @ gal bump to 91 in our area, which isn't inconsequential (what, $3 for a fillup?), but it does add up over time.

Did a search here; best I found was a thread from 2005, so I'll ask what the current thinking is.

Any harm in running the 2.0T on midgrade (89 octane) fuel? Does it degrade performance by retarding the timing? Any other thoughts?
Thnx,
Moon
I'd love to have a dollar for every post I've responded to from folks who want to run Premium in their cars designed for Regular (thinking they'll get better performance and or have a cleaner engine) and vica-versa (thinking they'll save money).

The thing is, if you run midgrade fuel in your car the timing will get retarded and the boost levels will be reduced. In the end your fuel economy will likely suffer to a greater degree than what you've saved by buying fuel which is less than optimal for your car.
 
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Old 03-21-2012 | 07:00 PM
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always use the recommended octane.
 
  #4  
Old 03-21-2012 | 10:22 PM
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The consensus of the older posts as well as some responses here seem to indicate that the midrange really does no harm, but the retarding in the timing and loss of fuel mileage may well negate any benefit of using the cheaper fuel.

The 2.0 turbo is such a treat that I really hate to risk anything that reduces its effectiveness.
Moon
 
  #5  
Old 03-21-2012 | 10:38 PM
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Originally Posted by halfmoonclip
The consensus of the older posts as well as some responses here seem to indicate that the midrange really does no harm, but the retarding in the timing and loss of fuel mileage may well negate any benefit of using the cheaper fuel.

The 2.0 turbo is such a treat that I really hate to risk anything that reduces its effectiveness.
Moon
Yup, good thinking.
 
  #6  
Old 03-29-2012 | 12:39 PM
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Originally Posted by halfmoonclip
The consensus of the older posts as well as some responses here seem to indicate that the midrange really does no harm, but the retarding in the timing and loss of fuel mileage may well negate any benefit of using the cheaper fuel.

The 2.0 turbo is such a treat that I really hate to risk anything that reduces its effectiveness.
Moon
I agree here... I've only used Premium in our A4 and with how great it runs and still managing to get 27-31mpg, I wouldn't risk running anything else.
 
  #7  
Old 03-30-2012 | 08:40 AM
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The Audi engine really does its best work on the open road; we get mid to low 20s around town, but there's a Focus in the garage that does much better than that locally, and on regular, so we mostly drive that for shorter hops.

Apparently the boys from Bavaria and at Ford are going the turbo four route for mileage and performance. Audi's been ahead of the curve on this, and the 2.0T has a great rep for power, economy, and not feeling like a rough four cylinder.
Moon
 
  #8  
Old 03-30-2012 | 09:24 AM
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I run super in my weed wacker.
 
  #9  
Old 03-30-2012 | 09:09 PM
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I'm a mechanical engineer, and I've taken several thermodynamics classes and one dedicated to internal combustion engines. If your car needs premium fuel, use premium. If it doesn't need premium fuel, you're wasting your money and will get no added performance.

Short technical explanation - The octane rating on fuel is basically a way to measure its resistance to autoignition, or engine knock; you may actually hear noise during this case. This is when the fuel mixture within the cylinder combusts in the cycle before the spark plug goes off (due to high compression). This situation is very bad for your engine and can require the replacement of different components.
 
  #10  
Old 03-31-2012 | 08:32 AM
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The supermarket where we buy our groceries has a 'fuel perks' incentive that gets you a discount on fuel at a gas station that is part of the supermarket complex.
You are allowed to buy up to 30 gallons of fuel with the discount, so I'll take some Jerrycans (the new, federal cans, grist for another topic, grrrrrr!) and get the max allowable. Usually I get hightest so it can run in anything in the house in a pinch.
Due to this, from time to time, the I-6 in my Jeep gets a tank of the good stuff (it normally runs on regular, as per the manufacturer). 'Valve clatter' is part of life with the old I-6, an engine that originally powered Roman chariots near as I can tell. They have always run great, but they sound like hell. Some high-test totally quiets the valve clatter.
Moon
 


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