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Is Higher Octane better

watsowatso Posts: 2
edited April 2014 in Volkswagen
Is higher octane better for engines?
I have a 97 Volkswagen Jetty GAS and a 97 Volvo 850 GET.
Due to the increasing gas prices my wife wants to switch from 92 to 89 or even better 87.
I am worried about what this might do to the engines over a long period of time.
Is there any evidence on why higher octane is better for your car? Any advice on this matter will help. Thanks

Comments

  • brorjacebrorjace Posts: 588
    Watso, for the most part, the premium fuels are oversold in this country. While there seems to be a greater percentage of cars that require premium (usually 91 octane or better), 87 octane is still the best choice for most.

    In short, check your manual. In order to get higher performance from the same size motors (and not drastically increase consumption or emissions), manufacturers are switching to ignition and fuel systems that require higher octane. This should be taken into consideration when puchasing a vehicle.

    Use of 87 or 89 octane gasoline in a car designed for 91+ is usually OK for a tankful or two but performance will probably seem sluggish and continued use may result in engine damage.

    If you calculate the costs of octane per dollar (or penny) you'll see that 89 octane is usually a bad deal. I'd alternate between tankfuls of 87 and 92+ if I wanted just a slightly higher octane in my car.

    --- Bror Jace
  • mike_542mike_542 Posts: 128
    Many people believe that premium gas is the best gas. Not true. Premium simply means premium price for higher octane. Octane is a simple measurement for a gasoline's ability to resist engine knock, a rattling or pinging sound that results from premature ignition of the compressed fuel-air mixture in one or more cylinders.

    Most gas stations offer three octane grades: regular (usually 87 octane), mid-grade (usually 89 octane) and premium (usually 92 or 93). The ratings must be posted on bright yellow stickers on each gasoline pump. The misnomer about octane is that the higher the rating, the better or more smoothly your car will run. In fact, premium gas can be bad for your engine if it was not designed to run at a high-octane level.

    Although it may seem that the term preminum or high octane implies that more energy is available, premium gas does not produce more energy than regular or mid-grade fuel. The octane grades are designed to accommodate engines with different compression ratios. High compression engines, found in most performance cars, require a fuel that burns efficiently at a higher temperature. That';s what premium fuel does, it burns hot under high compression. In a normal engine, premium fuel does not burn completely, resulting in excess carbon build-up and carbon fouling of the spark plugs. The end result is a less efficient engine that requires tune-ups more frequently. Oh, yeah, did I mention it also wastes money?

    The only time you might need to switch to a higher octane fuel is if your car engine knocks when you use the recommended fuel. This happens to a small percentage of cars. Check your owner's manual to determine the right octane level for your car. Regular octane is recommended for most cars. However, some cars with high compression engines, like sports cars and certain luxury cars, need mid-grade or premium gasoline to prevent knock.
  • zandorzandor Posts: 67
    Except about the "sports and certain luxury cars" using higher octane gas. Some "regular" cars need premium fuel, and some suggest using it but it's not really necessary (borderline compression & the computer adjusts to higher or lower octane fuel)

    For example, a 1999 Toyota Camry V6 should run on premium fuel. A nice car maybe, but not exactly a luxury or sports car. It's also even more of a suprise since other manufacturers extract similar (or sometimes more) power out of regular fuel with an equal displacement. I'm not sure about later models, since Edmunds seems to have gotten rid of that info on thier current new car pages (bad Edmunds!) and I haven't bothered digging around elsewhere.

    So check your owners manual or look on the car, as it'll usually have a sticker indicating the fuel requirement. (and check before you buy). "Regular" cars may need "premium" fuel as well.


    btw-

    you can get to old pages from '98 or '99 by going to

    http://www.edmunds.com/newcars/1998 or

    http://www.edmunds.com/newcars/1999

    For trucks substitute "newtrucks" for "newcars".

  • dj5dj5 Posts: 42
    Any opinion on what Brand of gasoline to use? Is there really any difference between a Brand name gasoline and a non-Brand name gasoline?
  • osucloneosuclone Posts: 4
    Hi. I just bought a Honda Accord Coupe EX-L. I love the car. The manual says to use any fuel at 86 octane or higher. I don't plan on using premium. Honda suggest using gas that has additives that prevent carbon building, etc. What brand of gasoline that has additives do you car buffs out there recommend? List several please. Thanks in advance
  • thanks for the detailed explanation.
    couldn't agree with you more.

    My Z3 says to use gas with an octane rating from 87-91. I've never heard the car knock with the cheap stuff '87, but some say my engine automatically retards combustion to compensate for the lower octane rating.

    I may be driving a retarded car, but I can't tell the difference.

    On the additive thing - I can't find a gas station in my neck of the woods that doesn't advertise some form
    of additive e.g. Chevron has techroline, Shell has their own and ARCO says there's no better gas with their
    additive.
  • brorjacebrorjace Posts: 588
    Yes, most brands of gas have additives in them already designed to keep your fuel system clean ...

    ... BUT, you will inevitably get a bad tank of fuel now and then. That's why I use a bottle or two of a good fuel injector cleaner each year ... along with some Isopropyl gas dryer to keep the moisture out of my car's system.

    Steverisity, I'm not sure if your M3 is retarded or not. You could drive the car hard (some flat-out acceleration) using your current fuel, then switch to something like 92-93 octane for a tankfull or two, repeat the 'test' abd see if you notice any change. But, if you bought the car just for its styling (or to attract women), 87 is probably fine. >;^)

    --- Bror Jace
  • riswamiriswami Posts: 192
    I think all gas manufactured in this country or for that matter sold has to have certain additives. I read this in the Federal Register. I don't have the specifics, but once I read it I wasn't too particular on brand of gas I buy. Have had no problems with injectors or carbon build up on intake valves.

    I used to throw Techron in every once in a while. Haven't used it in awhile. As far as brand A being better than brand B, I don't notice a differnce. Maybe there are differences? But how can you compare?
  • brorjacebrorjace Posts: 588
    Riswami, bingo. It's awfully hard to compare brands ... unless you have a problem (poor mileage, rough idle) and add one of these to your tank and see instant results.

    I've seen the immediate results of Redline SI-1 in my buddy's VW Rabbit (a drastic increase in mileage) and I saw the instant effect of adding Isopropyl alcohol to a V-8 Ford truck that got a bad (watery) tank of gas. It went from sputtering and almost stalling out ... to running perfectly fine a minute or two later.

    Basically, I think people should use 1-2 bottles of SOMETHING every year. Oh, and you should add them a tankfull or two before an oil change as the cleaners can make their way into your crankcase and dilute your motor oil. I know that Chevron warns specifically about this.

    Just avoid any cleaner/additive that admits to containing the corrosive alcohol "methanol." As far as I'm concerned, this junk should be illegal to sell as a fuel additive.

    --- Bror Jace
  • riswamiriswami Posts: 192
    Boor ace,

    Good point on adding the additive right before a oil change.
  • I recently purchased a 1993 Toyota Camry XLE V6. The manual recommends premium fuel, however it recommends it at 91 octane. I also saw an article claiming that premium fuel was a waste of money and no real value for a car like this. Does any one have some advise on the matter? What is the proper fuel to use in my '93 Camry?
  • nrauchnrauch Posts: 3
    I have a 1998 Ford Ranger XLT, V6. Manual says to use 87 octane. We have 88 octane where I live so have been using that. The pickup will still ping when driving at highway/interstate speeds on hills or when accelerating going into 4th or 5th gear. Do you think using a higher octane ( 91 I think is what we have ) would help or might there be another problem?
  • brorjacebrorjace Posts: 588
    rzielsdorf, for MOST cars using premium (higher than 87 octane) fuel is a waste but more and more are recommending higher octane to get more power out of their motors.

    You should use the grade recommended in the manual.

    nrauch, it's common for ignition systems to start acting up as they age. My Dad's Mercury specified 87 octane but as it aged, he required higher octane to keep it from pinging while under load (accelerating, hills, etc ...). I had a buddy with a 4.0L Cherokee that did the same thing.

    You can simply use the better (more expensive) fuel or you can try to find out if it's something in the timing, ignition, etc ... but that can be a nightmare to diagnose. Your choice.

    --- Bror Jace
  • rchinnrchinn Posts: 23
    Manual says: Octane 87 or higher. For improved vehicle performance, the use of premium unleaded gas with an octane rating of 91 or higher is recommended. I've been using 87 because I really don't want to pay the extra 20 cents per gallon. Please clear this up for me: will using premium 91 increase power, increase MPG??? Or is it really a waste of money as I've read in this forum?
  • brorjacebrorjace Posts: 588
    rchin, a lot of engies have anti-knock sensors which retard the timing when they sense knock coming on. Use of higher octane fuels that are less prone to knocking allows the ignition to advance and you'll get more power from the engine.

    If you are satisfied with the performance of your car on 87 gas, I'd stick with it and save the money.

    Still, if it were me, I'd at least OCCASIONALLY use a few tankfuls in a row of 91+ octane and 'exercise' the motor once in a while.

    --- Bror Jace
  • rchinnrchinn Posts: 23
    Bror Jace-
    One of these days I will take your advice and try the 91 octane just to see how the car feels. Right now, I feel fine using the 87. thanks!
This discussion has been closed.