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Discussion Starter #1
Hey, what kinda gasoline are you guys using?

I have a B5.5 GLX. Does it matter if I use premium or lower octane gas? My check engine lights keeps coming on and I was wondering if maybe a lower octane gas would cause this...

Any feedback would be great...thanks.
 

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hmm its prob not the gas (unless youre chipped), because my dealer actually told me to use 87octane instead of 93, especially in the winter, because the gas burns cooler so it extends the life of your engine and decreases the risk of knocks... :thumbup:
 

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If I have to I use 91 but normally I get 93. Lower octane gas by itself won't cause a CEL but you will get less power and mpg.
 

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I heard it depends what engine you're running also. I have the V6 and I find I actually get better gas mileage and performance out of the 93. But the type of gas your running shouldnt affect your check engine light.
 

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If you are way over the top on details, you can read thru some tests I did. I am especially interested if someone knows the VAG-Com groups I am using are not valid for my tests.
http://www.dub-tech.com/index.php?showtopic=54

Anyway, my current bottom line is to run 90 octane when it is generally less than 40 degrees. When it is warmer, I will use 92.
 

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Speedracer, your dealer is not that bright.

Lower octane, by definition, is more susceptible to knock than higher octane gas. The whole point of getting higher octane gas is to reduce knock in certain engine designs, like ours. Lower octane gas does not "burn cooler". It may ignite at a lower temperature/pressure, but this does not mean the engine is going to be any cooler after the gasoline has burned.

SirWired
 

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I've got the 2000 V6 GLX 4Motion, and I try to run 91 (highest in SoCal)... but the prices are killing me, so I dropped to mid grade 89. No engine noise or problems (other than my control arms).
 

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sirwired said:
Speedracer, your dealer is not that bright.

Lower octane, by definition, is more susceptible to knock than higher octane gas. The whole point of getting higher octane gas is to reduce knock in certain engine designs, like ours. Lower octane gas does not "burn cooler". It may ignite at a lower temperature/pressure, but this does not mean the engine is going to be any cooler after the gasoline has burned.

SirWired
That's what I was going to say :bow: ! It's so noticeble. You can actually "hear" the difference whether you're running 89 or 93. The low octane grade will make your engine knock.
 

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Heck...I think that OPEC and VW are in kahoots. Socking it to us little people.

Why else would VW put "Use Premium Fuel" all over their literature (at least that what it mentions for my 1.8T).

Orrrr....maybe they designed their engines to RUN ON THAT :crazy: .
 

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(V6) I started using 89 octane ever since the gas hike. I don't see a difference in performance or gas mileage. I haven't seen a choice for 91 octane. It's either 93, 89 or 87 :thumbdow:

I've been getting 89 octane......seems to be fine

Check engine light does not = bad gas>>>make sure the gas cap is turned at least 3 clicks :???:
 

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I'm still running 93 AKI. The stations here are still using about $0.10 spread for each octane increase (i.e., premium costs about 20 cents more a than a gallon of 87), sometimes less. The higher the price goes, the lower the proportionate spread is between 87 and 93. Right now, the premium is 11.4% higher than regular. Back in December, the spread was 14.3%.

If the talk (as evidenced here) is correct that you get better economy by using the recommended octane in a car designed to run on premium, it's conceivable that you could actually get to a point that using regular costs more than using premium (assuming the price spread stays the same).

Say the difference in mileage between using regular and premium is 10%. If the price hits $2.20/gallon for premium and if 87 costs $2.00, I break even. Any prices higher than that, and I actually save by using premium. I'm guessing that it's possible that some California members are already at that point, but don't know it (although I don't know what the price spread is between the octanes out there).
 

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Spsmcc said:
93 octane!?! they only sell 87, 89, and 91 here, whats the difference between 93 and 91?
Ummm, 2 points. :lol: I dunno, I only ran 91 octane once (in Canada). Honestly, can't say I noticed any difference. I think 93 AKI is actually above the recommended octane, but that's the only choice I have (we get the 87, 89, and 93 flavors locally).
 

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Lower octane gas will not damage the car!! It says in the car's manual. They do recomend 93 but you can use lower octane (thank god cuz i cant afford 93 - I always fill it up with 89 and some times 87). In europe I use 98 :)
 

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r3awak3n said:
Lower octane gas will not damage the car!! It says in the car's manual. They do recomend 93 but you can use lower octane (thank god cuz i cant afford 93 - I always fill it up with 89 and some times 87). In europe I use 98 :)
LOL... :lol: :lol:

Ok...let me get this straight. You use 89 or 87 (because you can't afford 93) in the states but use 98 in Europe.

I can't even afford Europe :shock: .

Maybe I should start using 89 or 87 and take the wife to Paris.
 

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I don't think it is generally doing damage to run lower octane - as long as your engine can retard the ignition enough to prevent more detonation. For any of you running lower octane in moderate or warmer temps, I would log group 22 on a VAG-Com and see how much and how often your ignition is being retarded.

I don't know what the max is it can retard the ignition, but beyond that point you are risking damage to the engine.

As far as running higher octane, I would only do it when I wanted max performance and the cost was worth it to me. When I did my test with 95 octane, I bought 4 gals of 100 octane fuel at over $4 per gal (and that was last summer). It was mixed fuel I had in the tank which averaged to 95 octane. On a 90 plus degree day, my ignition was still pulled back when I would give it half throttle. This shows this isn't a black and white question, its a continuum. Even when I had great fuel, hard accel stil caused detonation, causing my computer to pull back the advance, lowering my potential HP.
 

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The manual for my 04 variant 4motion 1.8T says that the minumum acceptable octane level is 87. It recommends 91. It says an octane rating of *less* than 87 will result in knocking and engine damage.

I've been putting 87 in lately and after driving for many 1000's of miles on 93, I didn't notice much difference. Even mpg was about the same which is weird.

I say try a tank of 87 and see for yourself...it's not going to damage your engine according to the manual.
 
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