Jetta 2.5 liter 89 or 91 octane
Username or Email Address
Do you already have an account?
Forgot your password?
  • Log in or Sign up

    Welcome to VWvortex - The Volkswagen Enthusiast Website.
    You're currently browsing VWvortex site as a guest. Please sign up or sign in and take part in the conversation. VWvortex has over 750,000+ registered users discussing a wide variety of Volkswagen related topics. Take a minute to sign up to enjoy all the features of VWvortex.
    The Car Lounge
    Results 1 to 11 of 11
    1. #1
      Member hardcore4life's Avatar
      Join Date
      May 8th, 2010
      Location
      Mentor ,Ohio
      Posts
      3,135

      Jetta 2.5 liter 89 or 91 octane

      Not sure if its been posted before


      http://www.europeancarweb.com/tech/e...ven/index.html

      Any time there's an increase in gas prices you'll often see news stories posing the question: "Is premium fuel worth the premium price?" After the "expert" gives his two cents, the reporter will often conclude thus: "There you have it-if your vehicle runs fine on regular, stop throwing your money away on premium!" The average consumer can easily be lulled to the conclusion that there are no benefits whatsoever from running gasoline that costs a premium price of 20 cents more per gallon. The logic experts use to justify their claims is straightforward: If you run 87 octane and your car doesn't knock or ping, you'll see no difference if you use 89 or 91 octane. There are also claims that if your vehicle is only designed to run on 87 octane, you could possibly encounter problems from using higher octane."

      To test the "premium gasoline is a waste of money" theory, we borrowed an unmodified Jetta 2.5L designed to run on 87 octane. In order to get a more accurate read on performance and pick up on any drivability differences, we decided to do more than just dyno tests. We performed the various tests using four tanks of gasoline. Under real-world driving conditions, the tank was run from full to empty first on 87, then on 91, and then back to 87. With the last remnants of 87 the car was dynoed until completely empty, then refilled with 91 and dynoed again.



      "Pros
      • Increase of 1-2 mpg
      • Increased throttle response and smoother power transitions
      • Reduce risk of knocking or pinging
      • Reduce risk of horsepower loss from heat soak

      Cons
      • $0.20 per gallon price premium

    2. #2
      only a few tanks tested, and the difference was that small? I would imagine you can't draw any real conclusions from that, MPG wise.

    3. #3
      Member CostcoPizza's Avatar
      Join Date
      Jan 20th, 2008
      Location
      Los Angeles
      Posts
      3,389
      I started running 93 in my 2.5, its been 3 tanks, I haven't noticed much.

      But I did start at the beginning of summer, so maybe AC use has dulled down the experience

    4. #4
      One car with 4 tanks of gasoline put through it does not constitute a valid test of 87 vs 89/91/93 octane. You need a much larger sample size and more effective/thorough testing methods to even be taken seriously.

      (I knew research methods and analyzing statistical data would help me some day)
      Quote Originally Posted by winstonsmith84 View Post
      It ain't easy being an overweight, uneducated, Sunfire driving whoop whooping clown.

    5. #5
      Member haunted reality's Avatar
      Join Date
      Apr 18th, 2001
      Location
      Delton, MI
      Posts
      4,253
      Quote Originally Posted by mac dre View Post
      I started running 93 in my 2.5, its been 3 tanks, I haven't noticed much.

      But I did start at the beginning of summer, so maybe AC use has dulled down the experience
      I've only run 87 in mine so far, maybe I'll have to give it a shot to see if I notice any difference.

    6. #6
      Member caj1's Avatar
      Join Date
      Feb 16th, 1999
      Location
      Washington, DC
      Posts
      7,368
      Quote Originally Posted by mac dre View Post
      I started running 93 in my 2.5, its been 3 tanks, I haven't noticed much.

      But I did start at the beginning of summer, so maybe AC use has dulled down the experience
      Your ECU is tuned for 87 octane, so no you won't notice any difference other than a lighter wallet.

    7. #7
      Quote Originally Posted by caj1 View Post
      other than a lighter wallet.
      thus, the car feels snappier and slightly better mpg...weight reduction

    8. #8
      Senior Member feels_road's Avatar
      Join Date
      Jan 27th, 2005
      Location
      East Bay Area
      Posts
      22,371
      Quote Originally Posted by caj1 View Post
      Your ECU is tuned for 87 octane, so no you won't notice any difference other than a lighter wallet.
      I would think the ECU can easily handle ~85 to ~97 - most VWs can.

      Cars are different, but many VWs - even those predominantly marketed in the US - benefit from higher octane gasoline both in performance and mileage. Now, whether that difference is worth your regional price in your particular engine, that is another story.

      Where I live, premium gas is only about 15 to 20 cents or 5-6% more expensive - I easily get that much better mileage with it in my Passat, plus better performance, plus being farther away from knocking...

    9. #9
      Member caj1's Avatar
      Join Date
      Feb 16th, 1999
      Location
      Washington, DC
      Posts
      7,368
      Quote Originally Posted by feels_road View Post
      I would think the ECU can easily handle ~85 to ~97 - most VWs can.
      I'm not saying it won't handle it.. The my point is the ECU won't automatically advance timing to make use of the higher octane fuel. I'm also not sold on any meaningful positive MPG benefit by using premium, especially considering it's harder to burn.

    10. #10
      Member umeng2002's Avatar
      Join Date
      Jul 9th, 2003
      Location
      Miami
      Posts
      5,234
      You know, knock sensors only work after the car starts knocking, so premium gas should at least reduce any knocking.

    11. #11
      I run Chevron 94 octane with 0% Ethanol in my Cooper S.

      It likes it. A lot.