# What gas are you using?



## Reifle (Jan 14, 2003)

Recently bought an '07 Rabbit 2 dr. Intially car ran fine - told to use regular gas - 3 tanks later (Shell Bronze) ran like crap! Recently changed to Shell Silver and the car improved dramatically - better gas mileage as well! What are you using? I am thinking of trying a tank of 91 Vpower Shell... Opinions please!








Further down the forum someone mentioned knocking - when I use the premium Vpower the motor is quiet and overall runs smoother! 


_Modified by Audione88 at 8:56 AM 6-4-2007_


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## Blade-Runner (Apr 29, 2007)

*Re: What gas are you using? (Audione88)*

unleaded


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## thedriver (Jul 3, 2006)

shell 89 as much as i can. if i cant speedway 89


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## bweed83 (Feb 25, 2007)

*Re: What gas are you using? (Audione88)*

usually 93 or 91 octane from a major gas company, yea i think it runs better with high octane fuels, could be my imagination though


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## absoluteczech (Sep 13, 2006)

here we go again, this is gonna be a thread on 85 vs 91+


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## bweed83 (Feb 25, 2007)

*Re: (absoluteczech)*

yea ...the saga continues


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## Unilateral Phase Detractor (Aug 23, 2005)

*Re: What gas are you using? (bweed83)*


_Quote, originally posted by *bweed83* »_usually 93 or 91 octane from a major gas company, yea i think it runs better with high octane fuels, could be my imagination though 

I don't know if it necessarily runs better, but I do notice some knocking when going up slight hills when using 87, so therefore I use at least 89 and sometimes Shell V Power 93. Regardless, I always use Shell.


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## tagsvags (Nov 25, 2005)

*Re: What gas are you using? (classicjetta)*

SHELL or BP Premium only in my 2.5 Rabbit since new
and runs great, for a 2.5 L.


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## _V-Dubber_ (Jan 30, 2007)

*Re: What gas are you using? (tagsvags)*

93 octane only since day 1 from 711 only. Runs like a dream! http://****************.com/smile/emthup.gif


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## the.ronin (Feb 22, 2006)

*Re: What gas are you using? (_V-Dubber_)*

Almost always 87 and Chevron techron treatment every couple thousand miles.


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## Geo (Nov 14, 2000)

*Re: What gas are you using? (the.ronin)*

the lowest grade (87 around here)
racetrack, chevron, raceway, shell
I've been using walmart gas lately and it has seemed to get a bit more mileage out of the tank, not to mention walmart is the cheapest around here


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## SuperHare07 (May 21, 2007)

*Re: What gas are you using? (Geo)*

the cheapest I can find


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## EMI6-RBBT (Feb 27, 2007)

as long as the ethenol level hovers around 10% (nothing above 15), it should be okay. i personally use sunoco 91-93. 
i'm training my car for the giac chip.







kidding.
but seriously. shell can = too my ethenol.


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## BuddyWh (Nov 11, 2006)

*Re: What gas are you using? (classicjetta)*


_Quote, originally posted by *classicjetta* »_
I don't know if it necessarily runs better, but I do notice some knocking when going up slight hills when using 87.... 

ECU should pull timing if pre-ignition knock is detected, so if you're noticing knocking then something's broke. I'd take it in for warranty repair.


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## CanyonRabbit (May 23, 2007)

I've been using moonshine, that granny's been makin and shiii I'm up to 250horsepower, go GRANNY!


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## BuddyWh (Nov 11, 2006)

*Re: (EMI6-RBBT)*


_Quote, originally posted by *EMI6-RBBT* »_
i'm training my car for the giac chip.







kidding.


Or is it training for your pocket book...


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## Giuliano1711 (Jul 15, 2005)

Made the switch to 91 or 93 a few months ago.. Car runs much better and gas mileage has improved alot.. I recently tried shell Vpower and noticed that i get worse fuel economy than other 91 or 93 octane fuels. Anything over 87oct. FTW


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## kaner05jetta (Dec 16, 2006)

I realize that I get a bit more power using Shell V-Power. I can tell straight off the bat too because I just filled up with Shell after using Lukoil 87.


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## digitaltim (Apr 17, 2007)

*Re: (kaner05jetta)*

"puppets and stew meat"


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## Apoc112 (Jun 11, 2003)

87 always... i've had better performance in my old car with higher octanes, obviously, but i figure if i don't spoil myself with higher octane in the 2.5, i'll never miss the additional power.


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## crawl (Sep 24, 2006)

*Re: (Apoc112)*

For past 11 000 miles I used only Premium, but today decided to do small experiment and filled up with 87. I drove 10 miles so far, and car runs much smother now imo.
Before that I was not sure what first gear was for, cause car was kinda jumpy in it, but now I can actually use first gear as I take off.
Of course I need to drive a little more to tell you for sure what is the difference.


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## Giuliano1711 (Jul 15, 2005)

Maybe a change in fuel every once in a while helps the engine? I myself can say I noticed a big difference going from 87 to 91, not only in gas mileage but performance as well, car runs much better..On the other hand I've heard people comment on seeing a positive difference going from 91 to 87.


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## thedriver (Jul 3, 2006)

*Re: (digitaltim)*


_Quote, originally posted by *digitaltim* »_"puppets and stew meat"









LOL


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## EMI6-RBBT (Feb 27, 2007)

am i the only one wishing for scientific research on this? 
lol


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## BuddyWh (Nov 11, 2006)

*Re: (EMI6-RBBT)*


_Quote, originally posted by *EMI6-RBBT* »_am i the only one wishing for scientific research on this? 
lol

I think the most scientific "research" done is that by VW's engineers.
They say to use 87 octane. http://****************.com/smile/emthup.gif 


_Modified by BuddyWh at 8:04 AM 6-22-2007_


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## travis3265 (Nov 15, 2003)

*Re: (BuddyWh)*


_Quote, originally posted by *BuddyWh* »_
Or is it training for your pocket book...
















im not sure if u were being serious, so im not coming at you, but moreso the idea of this comment.
it only costs 10-12 extra PER MONTH to go from 87 to 93. the benefits are there whether you beleive it or not. if you dont have 10-12 extra per month in your wallet, you should very much evaluate your life situation and do something about it.
i just dont get how people are so serious about their cars, spend all this money in mods, wax it every day, show it off to everyone, put the best oil, the best tranny fluid in it....but cant spend 10 bucks more a month for quality gas.


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## BuddyWh (Nov 11, 2006)

*Re: (travis3265)*


_Quote, originally posted by *travis3265* »_
i just dont get how people are so serious about their cars, spend all this money in mods, wax it every day, show it off to everyone, put the best oil, the best tranny fluid in it....but cant spend 10 bucks more a month for quality gas.









To some... and I'm one... it's a car. That's it... a means to an end, not the end itself. As such it's subject to the usual trade-offs of what's important in life. Pampering it with gas that it just doesn't need... .
If it's important to you then do it... if it's not don't and feel no guilt. Real simple.
Oh, and by the way... and this is what I was getting at... the GIAC chip needs it so... it can't hurt to start early and get used to it if you're planning for one!


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## magilson (Apr 18, 2005)

The MINIMUM grade they allow is 87 (interesting how that corresponds to the US's lowest grades in the large majority of places).
Heck even my GTI can "run" on 87.
When testing the rabbit we saw a marked improvement in timing pull when switching even from 87 to 89. As for 93, I'd log it because I'm not sure going that far would be worth it.
Lesson? Log it to find out if it's worth your money.


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## BuddyWh (Nov 11, 2006)

*Re: (magilson)*


_Quote, originally posted by *magilson* »_
Heck even my GTI can "run" on 87.


As can my Maxima, but with that I do notice it... performance and gas mileage suffer.


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## EMI6-RBBT (Feb 27, 2007)

over the years, i've noticed that german engines need more pampering. 
so... why not use 91. most engines should be using 89 in the summer anyhow.


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## crawl (Sep 24, 2006)

*Re: (EMI6-RBBT)*

Ok. I's been another day on 87 and I can see obvious difference in performance. Although I can take off in first gear with out the need to up sift momentarily, other all engine respond became much smother on 87 (reed as slow). I don't wanna say that car became much slower, but it is noticeable. 
Next time at the pump I'm going back to Premium...


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## Jimmy Russells (Feb 4, 2007)

*Re: (crawl)*

If an engine is designed to utilize 87 octane, you're not going to gain anything by using 91, it's really that simple. If you understand how gasoline actually burns, you understand why. 
There are many factors which determine how much octane an engine requires... Compression ratio, timing advance, quench area, intake charge temperature, etc. The more octane you have, the _slower_ the fuel burns. If combustion continues past the point when the piston is just before TDC (top dead center), it's wasted. Obviously, it's a LOT better than having combustion occur before TDC (detonation) but it _is_ wasted if it occurs after.
Now, it is possible in high ambient temperatures that the computer will have to pull timing with 87 in order to stave off detonation. I really don't know if it makes much difference, but I have to believe VW spends a lot of time R&D'ing all this kind of thing. If they felt the motor would be better served running 89, they would have told us so. I completely agree with the previous poster about using what VW says is fine to use. 
87 always for me







. Comparing the Rabbit to the GTI in octane requirement is not fair, the GTI is recommended to run 91, the Rabbit is recommended to run 87. 



_Modified by RedRabidRabbit at 10:36 AM 6-23-2007_


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## magilson (Apr 18, 2005)

*Re: (RedRabidRabbit)*


_Quote, originally posted by *RedRabidRabbit* »_If an engine is designed to utilize 87 octane, you're not going to gain anything by using 91, it's really that simple. If you understand how gasoline actually burns, you understand why. 
There are many factors which determine how much octane an engine requires... Compression ratio, timing advance, quench area, intake charge temperature, etc. The more octane you have, the _slower_ the fuel burns. If combustion continues past the point when the piston is just before TDC (top dead center), it's wasted. Obviously, it's a LOT better than having combustion occur before TDC (detonation) but it _is_ wasted if it occurs after.
Now, it is possible in high ambient temperatures that the computer will have to pull timing with 87 in order to stave off detonation. I really don't know if it makes much difference, but I have to believe VW spends a lot of time R&D'ing all this kind of thing. If they felt the motor would be better served running 89, they would have told us so. I completely agree with the previous poster about using what VW says is fine to use. 
87 always for me







. Comparing the Rabbit to the GTI in octane requirement is not fair, the GTI is recommended to run 91, the Rabbit is recommended to run 87. 

_Modified by RedRabidRabbit at 10:36 AM 6-23-2007_

Not quite right.
The rabbit ECU, just like the GTI, is capable of adding and removing timing. As I said before _during actual testing of a rabbit running both 87 and a few days later 89_ we saw an reduction in the amount of CF (correction factor) meaning we saw less timing removed due to the ECU's interpretation of the signs of pre-ignition. We saw no more misfire's than we did with 87 either, meaning we haven't made the gasoline so difficult to ignite that it simply wouldn't or did so too late as you describe.
As I said before, the GTI can run on 87 with reduced performance as stated in the manual. I know it's popular to believe these two motors are so different, but not as much as you'd think when it comes to the effects of gasoline grades and performance... Is 93 going to help you? I don't know, and that's exactly why I said you should be logging to find out. I still stand by what I say, we saw an improvement just going to 89 from 87.
What VW engineers DID do was spend their time making an ECU that can run on almost any grade gasoline you throw at it. Something a lot more useful than spending time making it run on a specific grade. VW Engineers stated that the Rabbit can run on 87 octane for one simple reason. Who the h*ll is going to buy a rabbit that _requires_ a mid or premium grade gasoline? If your answer is you, then count your lucky stars that your 2.5's ECU can take advantage of it (to a point). It's a win-win! http://****************.com/smile/emthup.gif


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## BuddyWh (Nov 11, 2006)

*Re: (magilson)*


_Quote, originally posted by *magilson* »_
Not quite right.
The rabbit ECU, just like the GTI, is capable of adding and removing timing. As I said before _during actual testing of a rabbit running both 87 and a few days later 89_ we saw an reduction in the amount of CF (correction factor) meaning we saw less timing removed due to the ECU's interpretation of the signs of pre-ignition. We saw no more misfire's than we did with 87 either, meaning we haven't made the gasoline so difficult to ignite that it simply wouldn't or did so too late as you describe.
As I said before, the GTI can run on 87 with reduced performance as stated in the manual. I know it's popular to believe these two motors are so different, but not as much as you'd think when it comes to the effects of gasoline grades and performance... Is 93 going to help you? I don't know, and that's exactly why I said you should be logging to find out. I still stand by what I say, we saw an improvement just going to 89 from 87.
What VW engineers DID do was spend their time making an ECU that can run on almost any grade gasoline you throw at it. Something a lot more useful than spending time making it run on a specific grade. VW Engineers stated that the Rabbit can run on 87 octane for one simple reason. Who the h*ll is going to buy a rabbit that _requires_ a mid or premium grade gasoline? If your answer is you, then count your lucky stars that your 2.5's ECU can take advantage of it (to a point). It's a win-win! http://****************.com/smile/emthup.gif 

Isn't it normal to pull timing, based on conditions? almost any engine, running any "normal" (read: not avgas or racing) fuel? if so, it seems reasonable that it would pull timing less when running higher octane fuel. The question is... does it matter? can I feel it? does it improve gas mileage enough to offset the cost? 
Also... let's say you are right in your implication that the decision to put the label "requires 87 octane gas" behind the fuel door was for marketing reasons. Wouldn't it also be smart marketing to put something to the effect of "... but for extra fun, burn ninety one!" in the manual too *if it were true*? 
I know a couple people who absolutely swore up and down this:
http://www.fuelmagnetizer.com/ 
actually worked (OK, not that product but a less glitzy early 70's equivalent. There is great power in the placebo... just the fact this old snake oil endures today tells you something about that.) Show me some back-back dyno charts of the Rabbit... like Top Gear did for the GTI in England that showed appreciable improvement using premium but not for the "super-duper-premium" grades.
Having said all that, I think you may be right as regards VW's ECU tuning, I just don't think we take advantage from higher octane fuels with the standard program in the ECU. I've certainly never been able to detect it with my butt dyno or gas mileage... even with an unintentional blind test when I found out my wife was filling with premium out of habit when she drove it for a few weeks.
But GIAC's program does take full advantage of 91 octane... and maybe others, but GIAC's the only one with posted dyno comparisons.
I'm not trying to convince anyone to change back to 87... that's their choice, and yours, so enjoy your ride!
_Modified by BuddyWh at 3:33 PM 6-23-2007_


_Modified by BuddyWh at 9:20 PM 6-23-2007_


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## digitaltim (Apr 17, 2007)

*Re: (BuddyWh)*

Just for the hell of it I filled up with 93 today. I've been running 87 for 3K miles. I only drove about an hour with it after filling up. So far I haven't noticed any difference. I'll update if my opinion changes.
I may just fill up with 89 from now on to try to keep the engine cleaner...unless that's a myth too......


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## magilson (Apr 18, 2005)

*Re:*

You guys are funny.








Just go out and test it yourselves. My point was apparently completely missed...


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## BuddyWh (Nov 11, 2006)

*Re: Re: (magilson)*


_Quote, originally posted by *magilson* »_Just go out and test it yourselves. My point was apparently completely missed...









Why??







This is an _enthusiast_ site.... just do it. With enthusiasm










_Modified by BuddyWh at 4:20 PM 6-24-2007_


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## mclothier (Jun 10, 2007)

i use 87 in my 2.5 jetta and it runs fine. the gas cap even says 87 is recommended. also AAA claims that if a car is meant to run on 87 then filling it with higher octane is pointless. on the other hand, if the car is meant to run on 91 (where the hell do u get 93 im in cali i have never seen such a thing) and u run it on 89 or 87 then you will notice performance decreases ie decreased MPG, rougher acceleration etc. 
and one my thing to add a lot of the cheaper gas companies ie valero, olympian, no name and i have my doubts about chevron and shell too: ever notice that when the truck comes to fill the enormous tank under the station, how many tanks does it have? 1 maybe 2. how many hoses filling the tank? again 1 or 2. now how smart do you think the guy drivin the truck is? not very if he was hed be working in the petrol plants down in the gulf. so where i am going with this? the pump offers 3 types of gas. how do they pump 3 dif types in to 1 or 2 tanks. well they dont. its all the same, and they charge you .50 more per gallon for it. check it out next time ur fillin up at night, hang around and watch, only 1 hose with 1 tank...its all a government scam to take our hard earned money. my 2 cents! dont take offense to my logic, but do take it seriously, there is a little humor in this as well


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## magilson (Apr 18, 2005)




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## THE KILLER RABBIT (Jun 2, 2003)

i use 87 per owners manual minimum requirments


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## Jimmy Russells (Feb 4, 2007)

*Re: (magilson)*


_Quote, originally posted by *magilson* »_
Not quite right.
The rabbit ECU, just like the GTI, is capable of adding and removing timing. As I said before _during actual testing of a rabbit running both 87 and a few days later 89_ we saw an reduction in the amount of CF (correction factor) meaning we saw less timing removed due to the ECU's interpretation of the signs of pre-ignition. We saw no more misfire's than we did with 87 either, meaning we haven't made the gasoline so difficult to ignite that it simply wouldn't or did so too late as you describe.
As I said before, the GTI can run on 87 with reduced performance as stated in the manual. I know it's popular to believe these two motors are so different, but not as much as you'd think when it comes to the effects of gasoline grades and performance... Is 93 going to help you? I don't know, and that's exactly why I said you should be logging to find out. I still stand by what I say, we saw an improvement just going to 89 from 87.
What VW engineers DID do was spend their time making an ECU that can run on almost any grade gasoline you throw at it. Something a lot more useful than spending time making it run on a specific grade. VW Engineers stated that the Rabbit can run on 87 octane for one simple reason. Who the h*ll is going to buy a rabbit that _requires_ a mid or premium grade gasoline? If your answer is you, then count your lucky stars that your 2.5's ECU can take advantage of it (to a point). It's a win-win! http://****************.com/smile/emthup.gif 

I am not arguing your findings, it's entirely possible with the 89 (and makes pefect sense) that the ECU has to pull less timing. Whether or not that has to do with testing conditions and temperature is another matter. Have you tested both octanes at various temperatures, humidities, etc? I bet VW has. 
I never said the 2.5 might have problems burning 89, I said it might not be able to burn it _fast enough_ to take advantage of it. 
Funnily enough, I just filled up at a station in town that offers 90 octane for the same price as 87 because I am curious to see the difference, if any. I'll post my findings in a few days. I usually avoid this station because I have been having the 2.5 stalling problems which seems to be related to ethanol fuels, but I'll forget about that for now. 
To the one poster in Cali, I think most of the country has 92 or 93... Up here we can get as high as 94 at most stations.


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## mclothier (Jun 10, 2007)

well thats just ludicrous. ive only seen 87, 89, 91, and no. 2 diesel. never anything higher than 91. thats crazy to see that. i have family in CT and even there i only saw 91.


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## digitaltim (Apr 17, 2007)

*Re: (mclothier)*

I'm in Ct...I never see 91....just 93


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## Jimmy Russells (Feb 4, 2007)

Yeah, here with all the various brands and stations we can get 87, 89, 90, 91, 92 and 94. One station usually has 3, and sometimes 4 different octanes. 
lol


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## absoluteczech (Sep 13, 2006)

*Re: (RedRabidRabbit)*

canadians....







jk
ive just filled up 3 tanks with 91 twice w/ shell and once w/ chevron 00000000000000 difference and 000 difference in gas mileage. if u got the 20-40 bucks extra a month cool no sweat off most ppls back but personally i believe theres 0 difference that 1 can feel. if it does make a diff it would be so slight u couldnt feel it anyways.


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## Codename-dnb (Jun 18, 2007)

*oregon gas*

Well here in Oregon its 87, 89, or 92
I use 100% 89 octane useally shell or chevron
Ive tryed 87 i had S*itty accl.
with 92 i dont notice a diff except in my wallet.....
so 89 it is runs great.....

here is a faq on gas octane.....
http://oregon.gov/ODA/MSD/docs...e.pdf


_Modified by Codename-dnb at 2:19 PM 6-26-2007_


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## silverA4quattro (Jun 22, 2004)

*Re: (travis3265)*


_Quote, originally posted by *travis3265* »_

it only costs 10-12 extra PER MONTH to go from 87 to 93. the benefits are there whether you beleive it or not.
but cant spend 10 bucks more a month for quality gas.









Wow, where to start. 
First off, what benefits are there? The manual clearly states that 87 or higher octane fuel can be used. No where does it recommend premium fuel, like say a GTI. My MKIV GTI can run on 87 as well, but 91 is recommended for max performance. The Rabbit has no such disclaimer, it simply states 87 or higher. Furthermore, I dynoed my car on 87 octane and if you factor in driveline loss, it made slightly more power than is stated by the factory, including SAE correction. That leads me to believe I'm not losing power by running 87. 
Secondly, higher octane gas does NOT equal higher quality gas. Octane rating is simply the fuels resistance to detonation. Now, some makers put higher detergent levels in their premium fuels, but if you're using a quality gas this isn't an issue. This horse has been beat to death thousands of times: If the car is designed to run AS DESIGNED on 87, it's all you need. The GTI is a different animal, it's designed to run on 91 or higher, but has a capability to cope with lower, with reduced performance.
All that being said, the only definitive way to test this is to log the various octane ratings, under high loads with VAG-COM. See which is pulling timing, etc. Until someone does this, I personally find no reason to run higher than 87 octane fuel in a 2.5. And for the record, my GTI ALWAYS gets quality 93 octane fuel. 
All of this is moot if you're chipped of course.


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## magilson (Apr 18, 2005)

*Re: (silverA4quattro)*


_Quote, originally posted by *silverA4quattro* »_All that being said, the only definitive way to test this is to log the various octane ratings, under high loads with VAG-COM. See which is pulling timing, etc. Until someone does this, I personally find no reason to run higher than 87 octane fuel in a 2.5. And for the record, my GTI ALWAYS gets quality 93 octane fuel. 

You should read the whole thread...


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## silverA4quattro (Jun 22, 2004)

*Re: (magilson)*


_Quote, originally posted by *magilson* »_
You should read the whole thread...

I did read the whole thread and I did see that you saw a difference. But we know nothing of how scientific your tests were. 
Logging needs to be under identical conditions, load, etc. I think the only truly definitive way is to log and dyno the types of gas.
I dynoed my car on 87 octane fuel, and made at least manufacturers claimed HP. So if more power can be made simply by switching octane, I'd be surprised. Pleasantly surprised of course.
Perhaps GIAC can shed some light on this, maybe they dynoed on 87 and 93, seeing how they recently came out with programming.


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## digitaltim (Apr 17, 2007)

*Re: (silverA4quattro)*

I read up on octane etc........all texts said anything beyond the recommended octane is a waste. There was some mention of higher octane helping excessive knock though. I read some companies use too much detergents too.
1/8 tank of 93 burnt and I swear the engine sounds different.
Seems quicker to me too.
Does it make sense that the engine sounds different? Almost like it doesn't wind up the same.
I know the "seems quicker" could just be my imagination, but it does seem so.
I'll play with the pumps a little......go back to 87 etc.......then 89


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## magilson (Apr 18, 2005)

*Re: (silverA4quattro)*


_Quote, originally posted by *silverA4quattro* »_
I did read the whole thread and I did see that you saw a difference. But we know nothing of how scientific your tests were. 
Logging needs to be under identical conditions, load, etc. I think the only truly definitive way is to log and dyno the types of gas.
I dynoed my car on 87 octane fuel, and made at least manufacturers claimed HP. So if more power can be made simply by switching octane, I'd be surprised. Pleasantly surprised of course.
Perhaps GIAC can shed some light on this, maybe they dynoed on 87 and 93, seeing how they recently came out with programming.


I have no idea how scientific your Dyno was...








A dyno is no more accurate a way of testing octane performance than driving the same section of road. What were the conditions of the dyno? What kind of dyno? What was your tire pressure? What was the temperature? What kind of ventilation are the running?







Who knows, maybe "your" dyno gives higher numbers than other dyno's and that's why you saw VW's numbers... It's not more BS than the way I tested...
Seriously. You guys crack me up.


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## silverA4quattro (Jun 22, 2004)

*Re: (magilson)*


_Quote, originally posted by *magilson* »_

I have no idea how scientific your Dyno was...








A dyno is no more accurate a way of testing octane performance than driving the same section of road. What were the conditions of the dyno? What kind of dyno? What was your tire pressure? What was the temperature? What kind of ventilation are the running?







Who knows, maybe "your" dyno gives higher numbers than other dyno's and that's why you saw VW's numbers... It's not more BS than the way I tested...
Seriously. You guys crack me up.









Instead of being all sarcastic, why don't you just answer the damn question? When you logged with VAG, was the ambient temp the same, load, etc? There are so many variables involved. 
I never said my dyno was scientific or a comparison for anything else, I simply stated what the car produced on 87 octane. Furthermore, I posted a very comprehensive thread when I did dyno my car that answers almost every question you came back with. In summary, there were 4 pulls done back-to-back on the same gasoline. Tire pressure was at factory spec, etc. 
Simply put, my point is that we need a 2.5 thrown on a dyno, under identical conditions to test this accurately and see if higher octane fuel on stock programming does indeed make a difference. 

_Modified by silverA4quattro at 9:48 AM 6-27-2007_


_Modified by silverA4quattro at 9:49 AM 6-27-2007_


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## magilson (Apr 18, 2005)

*Re: (silverA4quattro)*

If you can explain to me a reasonable way to test octane by dyno that doesn't involve driving to the dyno on vapors, filling up with enough fuel for a few runs, bleeding the system dry, adding the next octane level, driving around to let the ECU adapt properly, and then getting back on the dyno with identical conditions then I'll back off.
But when you come back down to reality and realize that won't happen, then we can talk.
I encourage you to do some logging as I had. Until then, your just blowing smoke. http://****************.com/smile/emthup.gif 
As far as reading articles about higher octanes and their affects, I don't suppose any of them were written about the ME7 ECU that is in your rabbits? The same ECU that can adapt timing and fueling based on more parameters than you can imagine?
I'd love to keep the sarcasm out of my comments, but the comments I see in here just bring it out in me. It's obvious I could bring forth no evidence that wouldn't be shot down due to imperfect conditions, unscientific-like tests, or 2.5 Bashing. Enjoy your cars and get back to me when you guys break out your Vag-Coms and dyno plots and stop reading articles that don't relate to your specific car in any way and then we'll have something to talk about.


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## BuddyWh (Nov 11, 2006)

*Re: (magilson)*


_Quote, originally posted by *magilson* »_....
I encourage you to do some logging as I had. Until then, your just blowing smoke. http://****************.com/smile/emthup.gif 
....

What does the logging prove? that regular pulls timing _more_ than premium?
What does that mean?
Not much... all alone...


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## silverA4quattro (Jun 22, 2004)

*Re: Re: (magilson)*

magilson,
In theory, the ECU should not be correcting for detonation at all and thus not pulling timing if the car was tuned for 87 octane. Therefore, again in theory, there should be no advantage to running higher octane. 
Obviously I'm curious about all this however and I will do some logs in the near future with stock programming. Do you happen to remember which block you logged? I remember doing this on my B5 with 93 octane to see if there was room for performance with higher octane on stock software. My results concluded that higher octane could not be taken advantage of, in stock form.


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## magilson (Apr 18, 2005)

*Re: (BuddyWh)*


_Quote, originally posted by *BuddyWh* »_
What does the logging prove? that regular pulls timing _more_ than premium?
What does that mean?
Not much... all alone... 

If timing had nothing to do with power, you'd be right...
But you're not.


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## magilson (Apr 18, 2005)

*Re: Re: (silverA4quattro)*


_Quote, originally posted by *silverA4quattro* »_magilson,
In theory, the ECU should not be correcting for detonation at all and thus not pulling timing if the car was tuned for 87 octane. Therefore, again in theory, there should be no advantage to running higher octane. 
Obviously I'm curious about all this however and I will do some logs in the near future with stock programming. Do you happen to remember which block you logged? I remember doing this on my B5 with 93 octane to see if there was room for performance with higher octane on stock software. My results concluded that higher octane could not be taken advantage of, in stock form. 

You need to be logging Correction Factor (CF). Your ECU will still change timing according to the correction factor you will see even if you aren't experiencing actual knock. To find out if you are experiencing actual knock it may be a good idea to log your knock sensor voltage simultaneously. The ECU is capable of correcting timing for each individual cylinder, not just total overall timing (it's pretty amazing actually).
Here are good references for logging.
http://www.ross-tech.com/vag-com/m_blocks/
http://www.mjbmotorsport.com/datalog.html


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## silverA4quattro (Jun 22, 2004)

*Re: Re: (magilson)*


_Quote, originally posted by *magilson* »_
You need to be logging Correction Factor (CF). Your ECU will still change timing according to the correction factor you will see even if you aren't experiencing actual knock. To find out if you are experiencing actual knock it may be a good idea to log your knock sensor voltage simultaneously. The ECU is capable of correcting timing for each individual cylinder, not just total overall timing (it's pretty amazing actually).
Here are good references for logging.
http://www.ross-tech.com/vag-com/m_blocks/
http://www.mjbmotorsport.com/datalog.html

Good information, I look forward to diving into this a bit further. Not sure how much time I'll have to play with the stock software though, I think I'm going to have to visit my friendly GIAC dealer soon.








I'll browse through those links, appears the VAG capability of these cars has come a long way from the B5 car I'm used to. 


_Modified by silverA4quattro at 8:19 PM 6-27-2007_


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## BuddyWh (Nov 11, 2006)

*Re: (magilson)*


_Quote, originally posted by *magilson* »_
If timing had nothing to do with power, you'd be right...
But you're not.

Don't start jumping to conclusions... nobodies said anything...
How much power? I'll grant that using regular causes it to pull timing some, point is how much power does that translate to.
Do you have a power vs. timing curve that is calibrated for a particular octane of gas? is there such a thing?
_Modified by BuddyWh at 9:10 PM 6-27-2007_


_Modified by BuddyWh at 9:11 PM 6-27-2007_


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## magilson (Apr 18, 2005)

*Re: (BuddyWh)*


_Quote, originally posted by *BuddyWh* »_Do you have a power vs. timing curve that is calibrated for a particular octane of gas? is there such a thing?
_Modified by BuddyWh at 9:10 PM 6-27-2007_

_Modified by BuddyWh at 9:11 PM 6-27-2007_

Not that I've ever seen. These modern Bosch ECU's base their operation after a desired torque ouput (basically).
The ECU is moving inside of maps based on air temps, timing pull (which is how it reacts to fuel octane rating), desired torque, load, etc...


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## BuddyWh (Nov 11, 2006)

*Re: (magilson)*

So then... from the logging you have done so far 87 octane pulls timing less, but we have no idea how much power that translates to.
Even you question whether a dyno test will be rigourous enough to settle the issue... but what if you log Vagcom during the runs. Then you can demonstrate the effects of octane on the timeing based on the log data you've already developed and then correlate that to the HP/Tq curve. Again, absolute HP numbers are meaningless, but you should be able to see that with less timing pull HP "trends somewhere".
Principle is all well and good, but iF you can't see that in the curve, then it's actual benefit is lost in the noise (of temperature, humidity, moon phase, whatever) and, imo, meaningless for all practical purposes. 


_Modified by BuddyWh at 4:29 AM 6-28-2007_


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## magilson (Apr 18, 2005)

*Re: (BuddyWh)*


_Quote, originally posted by *BuddyWh* »_So then... from the logging you have done so far 87 octane pulls timing less, but we have no idea how much power that translates to.
 
No. I saw less timing pull when running 89 octane.

_Quote, originally posted by *BuddyWh* »_Even you question whether a dyno test will be rigourous enough to settle the issue... but what if you log Vagcom during the runs. Then you can demonstrate the effects of octane on the timeing based on the log data you've already developed and then correlate that to the HP/Tq curve. Again, absolute HP numbers are meaningless, but you should be able to see that with less timing pull HP "trends somewhere".

My whole point was that you can't possibly do that without ending up doing the test with different conditions. As I said you'd have to drive around a while and let the 89 adapt. You can't just throw 89 in and expect instant results. That's not how these ECU's work... So doing a test on the same stretch of road under similar enough conditions truely is no worse than doing it on a dyno. I know of no place that can maintain the same conditions long enough to meet the crazy demands you guys have.

_Quote, originally posted by *BuddyWh* »_Principle is all well and good, but iF you can't see that in the curve, then it's actual benefit is lost in the noise (of temperature, humidity, moon phase, whatever) and, imo, meaningless for all practical purposes. 

_Modified by BuddyWh at 4:29 AM 6-28-2007_

Less correction factor is not meaningless. Once you get a better understanding of what these ECU's are doing you'll start to understand. By running a little higher octane you can start to eliminate some of the inconsistancies in timing pull through many conditions (the same conditions you keep saying will keep it from making a difference). As I said before, 93 might not be worth it, but I saw that 89 could. As soon as you go out and test this yourself, then we can have some kind of meaningful discussion. Until then you are just speculating. http://****************.com/smile/emthup.gif


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## Jimmy Russells (Feb 4, 2007)

*Re: (magilson)*

I typed a response in this thread last night, and then deleted it, but now it's just annoying me.

_Quote, originally posted by *magilson* »_ 
No. I saw less timing pull when running 89 octane.


And you're 100% certain that translates into more power, better economy, or some combination of the two?

_Quote, originally posted by *magilson* »_ 
My whole point was that you can't possibly do that without ending up doing the test with different conditions. As I said you'd have to drive around a while and let the 89 adapt. You can't just throw 89 in and expect instant results. That's not how these ECU's work... So doing a test on the same stretch of road under similar enough conditions truely is no worse than doing it on a dyno. I know of no place that can maintain the same conditions long enough to meet the crazy demands you guys have.


So why is his testing, and your testing any different? Did you run several tanks of fuel before the car letting the ECU adapt to octane level before doing your testing? I've asked before in this thread, and I'll ask again, were the ambient temperatures the same, the humidity levels the same, the engine temperatures the same?

_Quote, originally posted by *magilson* »_ 
Less correction factor is not meaningless. *Once you get a better understanding of what these ECU's are doing you'll start to understand.* By running a little higher octane you can start to eliminate some of the inconsistancies in timing pull through many conditions (the same conditions you keep saying will keep it from making a difference). As I said before, 93 might not be worth it, but I saw that 89 could. *As soon as you go out and test this yourself, then we can have some kind of meaningful discussion.* Until then you are just speculating. http://****************.com/smile/emthup.gif 


Stop being so condescending and acting as if we have no idea what we're doing. I've set fuel and timing maps on 7 second 1300 horsepower cars and you're going to try and tell me (or anyone else in this thread) I don't understand octane or how an ECU works. I've built engines for a living as well as had a 680 hp small block naturally aspirated Mustang running 9.70's on 114 octane fuel. 
You don't know any of us from a hole in the wall so just have a discussion about the topic if you wish, but leave the condescending remarks at the home page.


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## EMI6-RBBT (Feb 27, 2007)

i'm entertained.








but seriously... red = :thumbsup"


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## magilson (Apr 18, 2005)

You're all correct. It has no effect. Run 87 octane. Enjoy...


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## travis3265 (Nov 15, 2003)

all i know is that i have the giac chip, an intake, and ghl exhaust and my car runs like a dream on 93 octane. better than i could have ever imagined this car would do when i purchased it. it revs out to close to 7k, hits 65ish in 2nd gear, close to 100 in 3rd, and makes power up there while doing so. will i ever run less than 93.....nope. science this, science that....whatever. my car feels great with those mods on sunoco 93. key word being FEELS GOOD, thats all that matters. not these stupid studies, plots of this, logs of that. get over it.


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## digitaltim (Apr 17, 2007)

*Re: (travis3265)*


_Quote, originally posted by *travis3265* »_will i ever run less than 93.....nope. science this, science that....whatever. my car feels great with those mods on sunoco 93. key word being FEELS GOOD, thats all that matters. not these stupid studies, plots of this, logs of that. get over it.

wow, you sure told us all about your car mods and your feelings on the subject.
Though I thought they were talking about mostly stock ecus. Not Chipped which demands you to run 91+ anyways so... whatever.








I guess "we live in a society where individual ego is at the forefront" and studies are stupid?







Its funny man, don't take it too personally.


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## travis3265 (Nov 15, 2003)

*Re: (digitaltim)*


_Quote, originally posted by *digitaltim* »_








Its funny man, don't take it too personally.



wasnt aware i was. anyway, the point was, my car feels great on 93, so thats all the studying and graphing and dynoing i need. to each his own. whatever. i just wont run the "minimum". i ran 93 from the day i bought the car. ive done that in all my cars. its my decision. doing the minimum never got anybody anywhere, didnt your mommy's tell you that?


_Modified by travis3265 at 10:36 PM 6-28-2007_


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## vr_vento95 (Nov 26, 2004)

*Re: What gas are you using? (Audione88)*

I've used 87 oct since I bought the car in 12/06. I just switched to Sunoco Ultra 93, huge improvment!!! I noticed with the 87 going up hills at low rpms under 2k the engine would ping and was also sluggish. Now with the 93 it hasn't pinged once, has better gas milege and a little more pickup. http://****************.com/smile/emthup.gif most def worth the xtra $3.50 a tank.


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## John0 (Jun 2, 2007)

*Re: What gas are you using? (vr_vento95)*

Owned the car for a year today! After 9K I switched to 93 octane for my trip to get the chip (don't get me started on that....still waiting) and the whole ride down I honestly felt sportier performance than before, and even with my spirits dashed at not having the chip installed the car still seemed to perform better on 93. I would imagine that some of it is expectations, romping it a little more, and that it is a little more refined gas. I am excited for the chip when it will tell my car how to better utalize its new drink. like my liver tell my brain


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## magilson (Apr 18, 2005)

I love how all these people can come in here talking about how their butt dyno told them that 93 feels better but when I had actually looked into things with Vag-com all the little Rabbit tuner boyzzzzzzz came out of the woodwork and hated on me. I think I need to go start a post in the 2.0T technical forum talking about the 2.5 hate towards the GTI...


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## Apoc112 (Jun 11, 2003)

just an update... as i said earlier, i've been using 87 since the date of purchase (lil over a year now) and as a result of some replies on this (and related) threads as well as some personal curiosity, i'm now on my 2nd tank of 89. 
it costs me roughly $1.10 more per fill-up. i can tell a very distinct difference at low RPM shifts (+/- mode, AT).  i don't know how to best describe it, but with 87 octane my shifts are "push, *pause*, shift, *pause*, vroom". with 89 octane, it's "push, *pause*, shift, vroom". i've also tried to take note of the average RPM drop during a shift and it looks like it's about 200-300 RPM more efficient with 89 octane, although i plan on going back to 87 to properly test this.
overall, power delivery just feels smoother. i haven't been on 89 long enough to document real MPG gains, but i'll post up in a few weeks.


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## zukiphile (Oct 28, 2000)

*Re: (magilson)*


_Quote, originally posted by *magilson* »_... but when I had actually looked into things with Vag-com ...

After reading a couple of your posts on this, I mixed a half tank of 87 with 93. I notice no improvement in performance, but the engine seems quieter.
Would this indicate that some of the ordinary noise on 87 is a slightly audible knock?


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## magilson (Apr 18, 2005)

*Re: (zukiphile)*


_Quote, originally posted by *zukiphile* »_Would this indicate that some of the ordinary noise on 87 is a slightly audible knock?

If you can actually hear the pinging (if that's what it is) it's very not good. Try finding someone with a Vag-Com and logging Correction Factor or the knock sensor voltage itself. http://****************.com/smile/emthup.gif


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## zukiphile (Oct 28, 2000)

*Re: (magilson)*


_Quote, originally posted by *magilson* »_
If you can actually hear the pinging (if that's what it is) it's very not good. Try finding someone with a Vag-Com and logging Correction Factor or the knock sensor voltage itself. http://****************.com/smile/emthup.gif 

I can't hear any pinging. It just seems quieter with the higher octane.
I was introduced to the idea of inaudible ping in my youth when I played with the top speed of vehicles. I noted that a Suzuki Swift GTI that seemed to be good for only 110 mph on 87 could do 120mph on 93.
The answer I received was that inaudible ping was causing a minor power loss and the higher octane was solving this. Of course, that was in some respects a more primative engine.


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## magilson (Apr 18, 2005)

*Re: (zukiphile)*


_Quote, originally posted by *zukiphile* »_
I can't hear any pinging. It just seems quieter with the higher octane.
I was introduced to the idea of inaudible ping in my youth when I played with the top speed of vehicles. I noted that a Suzuki Swift GTI that seemed to be good for only 110 mph on 87 could do 120mph on 93.
The answer I received was that inaudible ping was causing a minor power loss and the higher octane was solving this. Of course, that was in some respects a more primative engine.

Bingo. You are correct. With that detonation came a loss in power. With higher octane gas (if you even need it) you'll have less timing removed and therefore more power.
But what do I know. There's a ton of people on here who know otherwise.


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## digitaltim (Apr 17, 2007)

*Re: (magilson)*


_Quote, originally posted by *magilson* »_I love how all these people can come in here talking about how their butt dyno told them that 93 feels better but when I had actually looked into things with Vag-com all the little Rabbit tuner boyzzzzzzz came out of the woodwork and hated on me. I think I need to go start a post in the 2.0T technical forum talking about the 2.5 hate towards the GTI...









You were in a discussion about the effects of different octanes. People questioned your results, but no one "hated on" you, because you drive a GTI.
I read what you posted and tried 93 for the hell of it......my "butt dyno" says there is a difference..... Sorry, I listened to you and tried it, but with out a vagcom.........big deal. 

Then you add insult with "rabbit tuner boyz" and the sarcastic reference to the GTi hating 2.5rs thread.
If anyone is showing any disdain towards you its because of your hypocritical statements. You give other people a hard time for doing exactly what you do.
Being a total newb here I did and still do look up to you, but you're changing that.
My point is.....I didn't read the posts as you did and I don't see any reason for you to be so offensive. 
Brush off the minor stabs and stick to your guns (facts).
You obviously have a lot of technical knowledge to offer. Don't let a bad attitude get in the way of that. 
You said you took readings that showed an advantage to using 89.....I respect that. I believe you.
Let people argue whether or not timing is an advantage.........We can all gain by others' insight.



_Modified by digitaltim at 10:07 AM 7-5-2007_


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## EMI6-RBBT (Feb 27, 2007)

i must have a dead foot or something. i use 91 and i don't notice anything. meh. but i <3 sunoco


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