# What grade of gas to use for 2.5 ?



## phukenvr6 (Mar 11, 2009)

I have been searching for this for a while and no luck. I have a 09 jetta I know the manual recommended gas is 87 octane. I was wondering if anyone runs a higher grade for any reason? 


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## lessthanalex (Oct 12, 2009)

If you've got any software upgrade you'll be running 91 or higher most likely. Otherwise I'd just stick with good ol 87.


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## vwluger22 (Jan 25, 2005)

93 with C2 software.


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## thygreyt (Jun 7, 2009)

oem specs recomend 91 for better performance


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## H3LVTCA (Oct 27, 2004)

I've found that higher octane gas (93) will yield as much as 11% better gas mileage in my '08 Rabbit.


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## jettafan[atic] (Dec 2, 2008)

SLiMeX said:


> I've found that higher octane gas (93) will yield as much as 11% better gas mileage in my '08 Rabbit.


 Do the gas stations you stop at sell zero ethanol premium gas? The ethanol content in the gas will affect the mpg you see a lot more than the octane rating will. "Octane" is just the rating of the fuels ability to resist pre-ignition. The 2.5 isn't a high compression ratio engine and it definitely shouldn't preignite or knock with 87 octane under normal circumstances.


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## phukenvr6 (Mar 11, 2009)

My car is all stock for now. Will I benefit putting in a higher grade? I've Been using 87. Would the mileage be better with 89 or 93? 


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## Salty VW (Sep 2, 2004)

Here's a great test that European Car did on the 2.5 using 87 octane, 91 octane, and 91 octane with an intake: 
http://www.europeancarweb.com/tech/epcp_1007_2010_volkwagen_jetta_proven/index.html 

Cliffs notes: The car ran just fine on 87 octane, but gained 1-2 mpg, 7hp, and 13ft/lbs of torque on 91. Something worth noting though is that the dyno graphs showed higher torque and just a hair higher horsepower under about 2800 rpm when running on 87 octane. The benefits of 91 octane don't really start to show until 3500 rpm. 

I personally don't notice much of a fuel economy increase with 91, so I tend to run 87 for day to day commuting and 91 when cruisin' around with the car club for those added few ponies.


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## TylerO28 (Jul 7, 2008)

Only 92 or 93 if I can find it. Apr chipped with all the bolt ons I've noticed the car not only idles better but power delivery is smoother and mpg is higher by around 10 percent. My fiance uses 87 and her jetta needs gas sooner than me however she drives less than I do weekly. However her car is bone stock. I tell her to use premium in fact when I fill her car up I use it. 
Honestly her car drives better with it.

I look at it as what's another 20 to 30 cents per gallon at the end of the year I feel its hardly any more than how much she spends with her constant fill ups..
Negligible amounts of cash truthfully


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## DerekH (Sep 4, 2010)

Even before i was chipped i ran 94, it just ran better.


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## thygreyt (Jun 7, 2009)

DerekH said:


> Even before i was chipped i ran 94, it just ran better.


 plus if you take care of the engine, it will last better


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## magics5rip (Mar 17, 2004)

I've run 91 a few times to see if there would be an MPG difference over the course of a tank. I did not notice a difference. From the dynos Salty linked to, you aren't seeing a bump in power till 3500rpm or so. For daily driving, it'll be 87 for me....unless I decide to get chipped and add a header.


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## phukenvr6 (Mar 11, 2009)

I filled up today with 93 to see if this week has a mileage change at all. If it's a performance only difference it doesn't really benefit me for daily driving. I got about 350 miles on the last tank


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## judas9mm (Mar 6, 2009)

thygreyt said:


> plus if you take care of the engine, it will last better


 Classic sucker for big oil marketing.


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## Salty VW (Sep 2, 2004)

I don't think it's actually "better" for the engine. The only reason you see a horsepower increase is because the ECU advances the timing to match the octane level. 

Essentially it automatically does %90 of what a performance chip would do once you add higher octane fuel and give it time to readjust.


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## thygreyt (Jun 7, 2009)

judas9mm said:


> Classic sucker for big oil marketing.


 not really. 
i did some testing with vag com, logging data from various sensors in the engine and with different octanes and brands. and in MY car, there were differences. 
hence my post.


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## magics5rip (Mar 17, 2004)

Salty VW said:


> The only reason you see a horsepower increase is because the ECU advances the timing to match the octane level..


 This is my assumption for the HP gains as well.


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## thygreyt (Jun 7, 2009)

magics5rip said:


> This is my assumption for the HP gains as well.


 most stock ecu's can only acomodate by as much as 25%. 
meaning, it will show gains, but it isnt as specific or as effective as an aftermarket software.


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## DerekH (Sep 4, 2010)

Man, it sure is awesome having thygreyt around. Means that i don't really have to say anything. He just says it all before i get here lol.


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## BlackRabbit2point5 (Sep 6, 2007)

we only have craptastic 91 octane here in El Paso, regular is 86 and mid is 88. I wouldn't run the regular gas here in anything. That being said I decided to get a water meth kit for a bit of added stability and of course to run more boost. Seeing as how more boost is a non issue for most of you just run the best stuff at the pump that you can. I've only run 87 in two tanks on my rabbit, one was rolling it stock off the lot the other was when I was feeling broke, both instances were before I moved down to El Paso and long before the turbo. Car was noticeably smoother on the good stuff and I was plotting boosting the engine from day one.


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## thygreyt (Jun 7, 2009)

the more you mod, the more susceptible the car is to gas grades and quality. 
thats why an aftermarket turbo'ed car on 87 is STUPID. (we've all seen the thread.)


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## Unilateral Phase Detractor (Aug 23, 2005)

I run 89 if the ambient temperature is above 68°F (20°C) due to some moderate knock in certain situations. Since it's cold, I'm currently running 87.


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## crosshare (Mar 4, 2008)

I use 93 on my 07.


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## Lewylou78 (Jan 22, 2000)

My 2010 Golf 2.5L seems to love Shell V-Power (93 octane) gasoline.


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## PhAyzoN (Nov 29, 2010)

I use V-Power as well. With my previous car (99.5 A4 2.8) I always went to Sunoco (across the street from our Shell) for their Ultra93, until a bad batch of gas caused a laundry list of issues which led to me getting my Jetta 2.5 now. Never again will Sunoco fuel enter my gas tank.


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## seanmcd72 (May 14, 2008)

I use 89 Ethanol-free most of the time.


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## Shawn99/30V (Sep 28, 2000)

87!


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## _V-Dubber_ (Jan 30, 2007)

Have always used 93 octane since day 1 in both my 07 turbo'd Rabbit and 2010 Golf from 7-Eleven


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## cryption (Mar 28, 2006)

classicjetta said:


> I run 89 if the ambient temperature is above 68°F (20°C) due to some moderate knock in certain situations. Since it's cold, I'm currently running 87.


I'm similar ... I run regular in the winter and premium in the summer. Likely no advantage to either, but it makes me feel good haha.


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## phukenvr6 (Mar 11, 2009)

So, I got about 350 miles on 87 then filled with 93 got 300 on that tank. Does this sound weird? I think I'll just stick with 87 for now maybe till I get it chipped. 


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## crosshare (Mar 4, 2008)

PhAyzoN said:


> I use V-Power as well. With my previous car (99.5 A4 2.8) I always went to Sunoco (across the street from our Shell) for their Ultra93, until a bad batch of gas caused a laundry list of issues which led to me getting my Jetta 2.5 now. Never again will Sunoco fuel enter my gas tank.


werd. Sunoco and Hess are both sh!t. 

I use Shell V-Power or Mobil 93 or I'm walking. :laugh:


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## MKVJET08 (Feb 12, 2008)

I always ran 87 octane in my car. I now have C2 87 oct program and am skeptical about using any higher grade than 887 now. After seeing all this talk about how higher grades are better in our cars, i've been wanting to try it, but not sure how that would work out since i have aftermarket software designed for 87


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## magics5rip (Mar 17, 2004)

MKVJET08 said:


> I always ran 87 octane in my car. I now have C2 87 oct program and am skeptical about using any higher grade than 887 now. After seeing all this talk about how higher grades are better in our cars, i've been wanting to try it, but not sure how that would work out since i have aftermarket software designed for 87


It isn't going to hurt to run higher octane fuels. Higher octane fuel is just more resistant to pre-detonation.


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## darkk (Jun 22, 2006)

I run 93 oct in everything I own. Even my lawn mower and snow blower. This way if I ever need gas from my can for my 2.5T, I won't get the sh*t gas in it...:laugh:


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