Avoid High Octane Gas To Save Money At The Pump

Those higher-octane gas choices sit there at the gas station, looking down their noses at you and daring you to throw down the extra cash in order to buy the very best for your car. But unless you drive a high-end vehicle with a manual that specifically recommends the higher-octane fuel, you’re most likely best off with regular unleaded.

LiveCheap tells you to ignore the octane rating, least of all because you probably don’t understand what the number represents:

Simply put, the octane rating is a measure of the gasoline’s resistance to combustion. Higher octane gas requires more energy for it to explode. Higher octane gas also has lower levels of “knocking” which is what happens when gas explodes too quickly in the combustion process. If you took the pure hydrocarbon octane and measured it, it would get a rating of 100…. a perfect score. Gasoline is a mixture of hydrocarbons and hence has a lower than 100 score. The lower the score, the easier it is to combust, the earlier in the combustion cycle it explodes, and the more prone it is to knocking. Now you know why if your car knocks (which is a problem that can lead to engine damage), people will recommend a higher octane gasoline.

The bottom line is that most cars are designed for regular 87 octane gas, and your car isn’t classy enough to know whether you’re feeding it ground chuck or filet mignon.

Does Buying High Octane Gas Save You Money? [LiveCheap]

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  1. obits3 says:

    But I want to feel special…

  2. UCLAri: Allergy Sufferer says:

    Yeah, putting higher octane gas in my Honda Fit wouldn’t do a darn thing.

    On the other hand, putting 87 in my future M3… maybe not so smart.

    • BobOki says:

      While that is partially correct, I would still recommend using Top Tier fuels. They have more detergents in the gas than most companies provide, helping keep your valves etcetc running cleaner. A list of top tier gasoline brands are at: http://www.toptiergas.com/retailers.html
      As a driver of a high-end vehicle, I can tell you these DO make a difference.

      • nucwin83 says:

        Top Tier is a marketing ploy. Fuel companies have to pay to be included on the list. Fact of the matter is that every brand has their own formulation of detergents, and do pretty much the exact same thing. I’ve seen bad gas from Top Tier and bad gas from non-Top Tier stations. Do realize that no matter where you get your gasoline, the only difference is the additives, because most likely the fuel came from the same distribution point.

        • TPA says:

          That’s exactly what I was going to post — Most gas stations in an area will get their fuel from the same source. The additives get added to the top of the tanker after fueling and that’s about it.

        • JustLurking says:

          Fuel does indeed come from the same distribution point (with very few exceptions, like New York, that receives pipelined and tankered gas for distribution), but those additives do make a difference.

          Top Tier was requested by the auto manufacturers and not the gasoline companies. It was the brainchild of a GM engineer who kept seeing engines failing due to bad gas. He lobbied BMW and Honda to join the group and they agreed that poor U.S. fuel had made them look like chumps despite their superior engineering. Bad fuel can very easily kill a modern fuel-injection system, particularly on direct injected cars with piezo-electric, very high pressure injectors.

          Top Tier is not a marketing ploy as much as it is a plea by the auto manufacturers for the fuel resellers to clean up their game.

          Top Tier participation makes sense for larger fuel retailers and less so for the independents, who have a harder time requesting the best additive packages from the fuel depots. They just get the daily special, instead of a customized package.

          Top Tier is not BS.

      • UCLAri: Allergy Sufferer says:

        Meh. I’ll just wait for VTEC TO KICK IN YO.

      • PSUSkier says:

        ‘Cept hi octane gas in an engine that isn’t tuned to burn it will actually cause your catalytic converters to foul more rapidly because of deposits caused by improper timing (the spark with 91/93 octane fuel happens sooner than 89 because of the cooler and slower burn properties).

      • AnthonyC says:

        Do you have any sources for that? It was definitely true 2 decades ago, but today gas in general us more carefully formulated (detergents and all), and I’ve been told a number of times that differences in gas by brand are mostly a thing of the past.

  3. The cake is a lie! says:

    I don’t necessarily agree with that. I’ve done the math on my car and getting premium actually saves me money. I get more miles on my tank than with the lower grade and it equals usually a few bucks savings to me. It costs me an extra 2.50 per tank and I easily get an extra 40 miles out of it compared to the low grade, so it definitely makes sense to pay more at the pump in order to get another round trip to work out of it.

    • The cake is a lie! says:

      I’ll add that putting anything over 85 in my motorcycle causes it to backfire like crazy, so no more premium for that particular motor.

      • MauriceCallidice says:

        Lowest grade available ’round these parts is 87. Where are you getting 85?

        • Wriz says:

          It is common for high-altitude locations to have fuel with an octane rating below 87. I’ve used it on several occasions while in Park City, UT. It’s a place not too far outside of Salt Lake City and has an altitude of around 7000′.

          The rationale for this is the reduced atmospheric pressure. There is less air (and fuel) drawn into the cylinder, reducing absolute compression. Since higher compression makes pre-detonation more likely, this lower compression has the same effect as a higher octane rating. Therefore, the use of 85 octane fuel at high altitudes (in a vehicle designed for 87) is acceptable.

    • Chmeeee says:

      Does your car require premium?

      • Peacock (Now In Extra Crispy) says:

        Mine actually does. It’s in the driver’s manual and on a sign in the filler cap. I drive a 2000 BMW 5 series and the recommended fuel grade is premium. I’ve never used anything else.

    • B says:

      Are you sure your driving style isn’t effecting your math? Simply accelerating slower or not braking/coasting more as much can give you a noticeable increase in fuel economy.

      • The cake is a lie! says:

        You would think that, but this was based on a long drive that I used to take several times a year. I ran the test in the same month with similar weather conditions going the same direction. I got marked improvement in gas mileage using premium than I did using regular. I filled up and drove on cruise control at 80 mph till I got to the my next fill-up point. Running that same route with those same conditions and gauging your results is as scientific as I am able to get.

        It doesn’t do the same for every engine, obviously, but I’m just suggesting that people not avoid premium just because someone says it has no value. In the case of my ’05 Corolla XRS, there is definitely value there.

    • farcedude2 says:

      I actually had a similar experience, where in my car (which calls for mid-grade), I put in premium on a whim on a road trip, and got significantly better mpg, and also better miles per dollar.

      • kc2idf says:

        You got that better mileage because you were on a road trip. You burn less fuel per mile on long highway runs than short to medium runs in town. This is why there are two MPG ratings, highway and in-city.

        I used to drive a Subaru Impreza that got horrible gas mileage (18ish) on my six-mile commute. Get it on a road trip, however, and it got 34+ MPG — almost double.

    • GuidedByLemons says:

      Higher octane gas has slightly lower energy content and will give worse gas mileage (assuming no knocking with either fuel).

      In other words, unless you experience knocking with standard octane gas, you’re deluding yourself and wasting money.

      • dangermike says:

        Not necessarily true. In a maddern engine with variable valve timing and computer controlled ignition timing, an engine can run on a lower octane fuel smoothly by adjusting its operating parameters. The trade-off, as noted in the parent post, is less-than-optimal fuel efficiency.

        Further, recommending low octane fuel as a rule is irresponsible on the part of the consumerist. Running too low an octane fuel through too a motor with high compression, especially as is the case with any sort of forced air charging or other types of high performance engines, can and will damage the motor.

        • dangermike says:

          oops, maddern=modern.

          Also, wanted to add that the adjustments made by an engine to correct for too low an octane rating can also cause premature saturation of the catalytic convertor.

    • eturowski says:

      Makes sense – as the price of gas climbs, the differential price between gas grades is generally the same (~$0.10), so a difference in mileage at a higher base cost per gallon is more likely to be profitable. The more expensive gas becomes, the less expensive (relatively) it becomes to put premium gas in your tank.

      Say your car gets 10 mi/gal burning 87-octane fuel, which costs $1.00/gal. You’re paying $0.10/mi. If your car gets 12 mi/gal burning 92-octane fuel, which, at two grades higher, costs $1.20, you’re breaking even at $0.10/mi.

      Now, say the price of 87-octane gas increases to $4.00/gal. Then, at 10 mi/gal, you’re paying $0.40/mi. If 92-octane now costs $4.20 for 12 mi/gal, you’re only paying $0.35/mi. It’s actually cheaper, mileage-wise, for you to fill up with premium gas if a) you get better mileage with the premium gas, and b) the price differential between grades does not change proportionately to the increase in low-grade fuel.

    • commenterofsize says:

      Your experiment has selection bias, because you, the driver, knew what kind of gas was in the tank. You wanted the premium to have a higher MPG, so you may have subconsciously altered your driving habits accordingly.

      But that’s OK! If having premium fuel causes you to maximize your MPG, more power to you.

      It would be interesting to have someone else choose which fuel you’re using and run a few tanks of each.

      • TPA says:

        My cars call for “premium unleaded only”. There’s been a few times I’ve had to put in the lower grade fuels and noticed a substantial drop in fuel economy. (from 24 mpg to 18 mpg). Not sure about other cars.

      • GuidedByLemons says:

        “But unless you drive a high-end vehicle with a manual that specifically recommends the higher-octane fuel

        Not irresponsible, just true. Read better next time.

  4. TouchMyMonkey says:

    Real simple rule from the good old 1980s, when lots of cars that allegedly ran fine on 87 octane knocked and pinged like a new wave rock group on speed, and did encores after every show. Try mid-grade. Does your car still knock/ping/diesel? If so, try super. Otherwise, continue buying mid-grade and be happy.

    I had a Dodge Omni once. It would only run well on super. It would also get about 10% better gas mileage with super, which I now know is because knocking robs your car of both power and MPG. My next car was a ’91 Honda Civic, which I would spoil rotten with super until I figured out that unlike 80s Mopars, Honda engines were made properly and didn’t require it.

    • B says:

      Unfortunately this doesn’t work with newer cars, as electronic fuel ignition will prevent the car from knocking no matter what octane fuel you use. You’re better off going with what the manual recommends.

  5. mbnovik says:

    Does cheaper octane gas kills your fuel injectors?

    • nopirates says:

      no

    • Zowzers says:

      Nope, All the octane rating tells you is how much pressure that particular fuel can withstand before it spontaneously cum busts.

      Other then that, each brand still puts the same additives in each of their fuels regardless of octane.

      • TouchMyMonkey says:

        This is because gasoline is a commodity, and it all gets delivered through the same pipeline. it used to matter where you got your gas, once upon a time. It doesn’t anymore.

        And don’t pay any attention to the grease monkey at Jiffy Lube when he tells you your injectors need cleaning. It’s all BS.

        • Saltpork says:

          Injectors can have 2 problems: pressure & electrical.
          Pressure means that your fuel line needs to be purged or the injectors valves(for spraying gas) are shot & the injector needs to be replaced.
          The other issue is electrical in which case the entire injector assembly needs to be replaced or wiring harness repaired.

          If you want to keep your injectors clean, change your fuel filter as needed and don’t let your vehicle go below a quarter of a tank so your fuel pump won’t pick up the dredge from your gas tank.

          I have never had a need for pricey gas and probably never will as I don’t run million dollar vehicles.

          • Zowzers says:

            “don’t let your vehicle go below a quarter of a tank so your fuel pump won’t pick up the dredge from your gas tank.”

            Common fallacy, the fuel pump is at the lowest point in the fuel tank so its always pumping from the bottom. Aka any dredge sinking to the bottom gets pumped out 1st regardless of fuel tank level.

      • BobOki says:

        This is only partially correct. The octane rating explanation you gave was correct, however, the amount of detergents the companies put in are not standardized, and there are top tier gas brands which put more detergents into their fuel. http://www.toptiergas.com/retailers.html

        • ceriphim says:

          That’s the second time you’ve posted that link. Do you own stock in that company or what? As was pointed out earlier companies pay to get their names put on the list, and most fuel comes from central distribution points which can lead to contamination of one shipment from a previous one.

          It’s marketing BS. Why keep pushing it?

  6. grucifer says:

    87 in my Speed 3? No thanks!

    (Manual calls for 93)

    • Joewithay says:

      Yeah my Speed 3 only gets 93 too

    • ZJM says:

      Speed3 here as well!

      Unless the car requires it I say skip it. But with turbocharging becoming more popular, I expect a lot more motors will require it..

      Please read your manual before you decide which octane rating to purchase..

      • GearheadGeek says:

        As turbocharging is becoming more popular, direct injection is as well and it allows engine designers to build high-output turbocharged engines that can run well on 87. It’s all in the design… cars that are targeted more toward the generic transportation end of the market are going to use this technology to let them run on 87 even with turbos.

    • t325 says:

      My VW GTI only gets 93…91 if I’m running on fumes and can’t find a station with 93, but I know the ones near me that do have it.

      My car would get worse gas mileage with 87, so I figure it all evens out in the end and I get a likely barely noticeable performance boost that comes from 93.

      • grucifer says:

        Yea, there’s times I fill with 94 but from 93 to 94. There can’t be much, if any at all, difference there.

  7. Chmeeee says:

    The label premium is a misnomer, which leads to a lot of confusion with people who don’t know how these things work (most people). It’s not “better,” per se, just different. Like the article says, if you don’t need it, then buying it is just flushing your money down the drain.

    On the other hand, it absolutely boggles my mind how many people refuse to buy it for a car that requires it or even refuse to buy a car in the first place because that car requires it. We’re talking about a typical car purchase which probably results in payments of $400-$600/month, more if it’s a luxury car. If you drive 12k miles per year, then the extra cost to you to use premium is in the neighborhood of $8 per month, or 1 to 2 percent of the car payment.

    • Mom says:

      Not to be pedantic, but I’ll be pedantic….facts and figures easily checkable via google…

      The average person drives 15k miles per year, and the average gas mileage is 20 mpg, which actually makes switching to 91 octane cost $12.50/month for the average case. I’m guessing that the average mpg for cars that take premium will be skewed higher, so say it’s more like $15/month rather than $8.

      The average car payment is $380-460, not 400-600, too, btw.

      Anyway, that brings it up closer to 4% of the car payment, but point taken.

      • AnthonyC says:

        I’m glad you get the point, but the average car payment for cars that require premium gas will be higher than the overall average. And, if the better cars skew towards higher mpg as you claim, then that means fewer gallons of gas bought, so less price difference between regular and premium, not more.

  8. D0rk says:

    Even the lowest end of cars are smart enough to alter timing and such if it detects a lower octane to keep it running safe. And you’d be a fool if you try to take advantage of that to save

    • verdegrrl says:

      Typically the timing is retarded to eliminate or reduce knock. There is usually only so much retarding that can be done (there is a joke in there). Combine low octane in a car designed to run on higher grade, then place it in a hot environment, and place it under high load like going up a steep pass. There is usually only so much the computer can do to offset certain (admittedly) extreme conditions.

      One way this might be more applicable is that you typically don’t need higher octane at high altitude, so it can be hard to find. Drive the car down the hill on the same tank of low octane fuel and then place it under high load. Throw in a warm day.

      Just pointing out that there are ways limits can be exceeded.

      • hansolo247 says:

        True, with a distributor based ignition system.

        A car without a distributor is far more capable of retarding timing, as the spark is no longer the result of a physical event.

  9. namcam says:

    my Landcruiser gets better milage with premium. i have tried both, makes a few miles difference.

    • tbax929 says:

      I wonder why someone concerned with mileage would buy such a gas waster as a Land Cruiser in the first thing. What a ridiculous car.

  10. Hank Scorpio says:

    Unfortunately, my car requires 91 or higher. Which means I have to use 93, since for some reason it goes 87, 89, 93 – why the jump?

    On the other hand, I get great mileage (way better than my old car), so it more than evens out.

    • Shadowfax says:

      It depends on your location. Go to Denver and you’ll be hard pressed to find 91.

      It’s because at different altitudes, gasoline behaves differently. There’s already more “resistance to burn” at 5000 feet up than there is at sea level thanks to the lower oxygen count, so the octane doesn’t have to be as high to get the same result.

    • deadandy says:

      Your answer is in your question: so you have to buy the 93. :)

    • MaxH42 thinks RecordStoreToughGuy got a raw deal says:

      There are a couple of stations in my area that carry 91 octane, and they both price it $0.02 less than 93; it’s nice to have it available, but it’s only going to save you maybe $10-20 a year. I won’t go out of my way to gas up at those stations, I’ll use 93 instead.

  11. alSeen says:

    Better suggestion.

    Don’t buy the 10% ethanol gas.

    Sure it might be the same price for a higher octane, or even 5 to 10 cents cheaper. Your mpg suffers though.

    I get at least 5 to 10% less mpg when I use an ethanol blend. 10 cents savings at $2.80 a gallon is not enough to counter mpg loss.

    • jnads says:

      THIS.

      By me, the 89 is ethanol. It costs 10 cents more for 87, non-ethanol.

      I go for the non-ethanol because gas mileage is better. Noticably better.

    • TouchMyMonkey says:

      In New York, you either buy E-10, or you walk.

    • BobOki says:

      You get worse gas milage because it has to burn twice as much fuel to produce the power. Ethanol burns a lot cleaner however, and also can sustain a lot more pressure before combusting, making it a clear winner for the racer on the cheap.

    • Froggmann says:

      Would love to, but we can’t in California.

    • shepd says:

      That is bad advice for anyone in a cold climate. The ethanol acts as gas dry out. If they don’t put that in, and don’t add dry out, and you don’t add in dry out yourself, enjoy your frozen gas lines…

      • Wriz says:

        While ethanol does have the effect you are talking about, avoiding E10 is not necessarily bad advice in cold climates. I live in an area where the temperature regularly goes sub-zero for weeks at a time. I’ve never had an issue with gasoline that doesn’t contain ethanol.

        I make sure to run the tank pretty low before refueling. This has the effect of flushing out any moisture that may have accumulated inside the fuel tank. I know several people that are afraid to run their vehicle much below a half tank. Because of this, water has built up in their tanks and frozen in the lines on occasion. However, as you have mentioned, that issue is being mitigated lately by ethanol blend fuels becoming standard.

    • S says:

      I pass two gas stations on my way to work. They both charge the same per gallon for gasoline, but one of them doesn’t sell an ethanol blend. Once I figured out that I was getting 4.5 mpg better fuel mileage from the non-ethanol gasoline, I quit going to the other station.

  12. Beeker26 says:

    It also depends upon the age of the vehicle. As an engine ages it generally will require a higher grade of gas. But the proof is in the pudding, so to speak. If you can’t notice any performance difference (either in power, pinging, or gas mileage) between regular, mid-grade, or premium then there is no point is using anything but regular.

    Another tip: even if your car runs better on mid-grade or premium you can usually get away with using regular on long road trips, as highway driving put very little stress on the engine.

    • BobOki says:

      Trips are the best time to use better fuels. The higher octane ratings mean they will hold longer before combusting (higher pressure) which in a steady environment means you will use less fuel while retaining the same or better power. In other words, used during a trip, higher octane gasses burn more efficiently which means you will get much better gas mileage out of it then, as opposed to any other time. The higher the mileage per gallon, the more cost effective it is.

  13. Salty Johnson says:

    The explanation is slightly inaccurate. Gasoline is never supposed to explode. When your engine is running properly, gasoline burns smoothly. Octane measurement is an indication of how much pressure is required before the gasoline detonates, which causes knocking. High-performance engines run with higher cylinder pressure, which requires a higher-octane fuel so it doesn’t detonate. Many people think that putting higher-octane fuel in an engine that’s not running right will fix it… but as long as the engine isn’t knocking, higher-octane fuel won’t do diddly. It will have absolutely no effect.

  14. Fine Material says:

    The cost of premium over regular seems to have lessened recently. It’s now down to 3-4% locally. There is no mention here but wouldn’t premium give you 3-4% better milage?

  15. aeproberts says:

    As a car fanatic and amateur race car driver I can tell you that this article is 100% correct. Some cars (high end European models, cars with turbo chargers etc.) actually require premium fuel in order to run efficiently, otherwise you are just throwing money away.

    I will go one step further. NEVER EVER BUY 89 OCTANE GASOLINE. Any car that requires premium gas requires at least 91 octane or higher. Any car that doesn’t require premium gas will run just fine on 87 octane. 89 octane gasoline is purely a marketing ploy to lure unsuspecting customers to pay 10 cents more per gallon.

    • Beeker26 says:

      Is this true even for an older vehicle, say 7-8 years old? My friend has a 2002 Blazer and swears it runs better on 89 than 87.

      • Harry Manback says:

        The reason that older cars sometimes require higher grade gas is because deposits develop inside the combustion chamber, which reduces the volume and causes the compression to rise. This rise in compression can cause detonation, which will negatively impact both fuel economy and power. So it’s certainly possible that an older engine will run better with 89 than 87 without requiring 91 as the change shouldn’t be dramatic.

    • Fine Material says:

      One of my cars is a 2003 Saab 9-5. The owners manual says use 89.

    • deadandy says:

      Actually many motorcycles will run fine on 89 octane while the manufacturer will recommend premium. They will not, however, run on 87.

      • Harry Manback says:

        Actually, many motorcycles will run fine on 87 (see Suzuki SV650, Yamaha XT350, Honda XR650L, Kawasaki EX500…I think), and yes, the manual recommends 87.

    • Harry Manback says:

      My motorcycle requires 89, not 87 or 91 (my car requires 91), so that’s what I use.

    • tomz17 says:

      Stop slandering 89! Drove a Nissan Maxima (required 91), and now drive a BMW 335i (also requires 91) and I actually end up pumping 89 octane often. In the Northeast we can only reliably get 87,89,93… so ….

      Homework Question : If you have half a tank of 93 and half a tank of 89 what do you have?

  16. ganzhimself says:

    Not an option for those of us running turbo charged engines. Turbo + 87 Octane = boom.

    • rbb says:

      No. 87 Octane + turbo does not equal boom, if the engine was designed correctly. The 2.0T in my VW Eos prefers 91+. But, it it gets a tank of 87, then all it does is change the engine parameters like the timing to prevent knocking. It also shuts down some performance measures so the engine does not produce as much power. But, it will not cause the engine to go boom…

      • hansolo247 says:

        Correct.

        A modern turbocharged car will not detonate. The ECU will just lower boost, killing power, efficiency, and mileage.

        The older turbocharged cars didn’t go boom either…they had low compression ratios which is why they had so little horsepower.

        Now, Direct Injected turbo cars can have near 10:1 ratios. A car from the 90s or 80s didn’t.

  17. Battlehork says:

    She needs premium, dude! Premium! Duuuuuuuuude!

  18. TooManyHobbies says:

    Yup, if your car’s owner’s manual doesn’t call for high octane gas, then putting it in your tank is no different than just setting fire to money.
    Higher octanes fight knocking, but modern computer controlled engines detect knocking and automatically adjust engine timing to stop it anyway.
    High performance engines generally have higher compression ratios and therefore can be extra susceptible to early ignition, so some of them call for higher octanes.

  19. paulthegeek says:

    Occasionally, when I was feeling saucy, I’d put premium (93 octane) in my Saturn VUE 4-banger. It drove significantly better on the higher octane gas. Quicker off the line, and better passing power. Also, depending on how I drove that week, if I was careful I could get another mile or two per gallon. The same goes for my Honda VTX1300 motorcycle. More horses and better mileage.

    So, in general, yeah most cars don’t need high octane gas, and if cost is your bottom line then go with 87. But cars can run better on better gas and your mileage CAN improve. And some cars come with 93 octane recommendations from the manufacturer, not just “classy” cars either; Volkswagen recommends at least mid-grade for their turbo engines (1.8T, 2.0T, etc.) Same for some of the upgraded Subaru engines and the Mazdaspeed 3.

    • tomz17 says:

      Premium has nothing to do with horsepower unless you were tweaking your engine timings…

      There are only two possibilities here :

      #1) It’s all in your head

      #2) Your engine was gunked up (most likely due in part to running higher octane gas in the past) which caused the compression to rise… Then the knock sensors didn’t retard timing with premium gas and the rest of the time you were just knocking the engine all around town.

      Note : #1 is way more likely than #2.

      • Wriz says:

        Bingo! I’m with you on #1.

        “Quicker off the line, and better passing power.” Without objective performance measurement (e.g. a Stalker radar system) I call B.S. “Seat of the pants” is not an accurate measurement system.

  20. Miss Dev (The Beer Sherpa) says:

    Um – in Colorado “regular” is 85, “midgrade” is 87, and “premium” is 91, so what does this mean for us? Do we have different ratings because of the altitude? Should we also opt for 87 over 91, or 85?

    • Harry Manback says:

      If your manual says 87 or regular, then you can use the lowest grade (85 would be fine at high altitudes). 89 is often called mid-grade, and since my bike says it requires 89 I would use whatever the next step above the lowest is. My car requires 91, so for that I usually just use the highest octane that is available. Sometimes there are 4 grades (at sea level that would be 87, 89, 91, and 93) and you can think of them as regular, mid, premium (actually called “plus” in a lot of places), and “premiumer” (I don’t know of many cars that actually require 93, so I gave it my own name). If you only see 3 grades then you can bucket them as regular, mid, and premium, and then purchase accordingly.

    • silentluciditi says:

      Learned the hard way a few weeks ago that my car does indeed require a higher octane fuel. Put in Regular (85 in CO) instead of Mid-Grade (87) and performance suffered along with absolutely killing my mileage. Having to fill up an 18 gallon tank in half as much time as usual sucks. No savings there!

  21. MoreThanWYSIWYG says:

    People don’t really think a higher octane is better for the car, do they? Just because the # is higher doesn’t mean you car will run better on it. Would someone put super heavyweight tractor oil in there engine because the weight is SAE60 when their car calls for 5w30? I hope not….lol

  22. Thyme for an edit button says:

    People should just look at their manuals. My car is meant to get 86 or higher. No 85 for me.

  23. Back to waiting, but I did get a cute dragon ear cuff says:

    It varies by car. I have a 2002 Toyota Solara (a gussied up Camry coupe) and the manual says: For best performance use Premium gas. Well I have tried premium and regular and see no difference.

    When I was testing it for mileage, I was doing only my daily commute, driving easy and keeping a hard watch on the tach to try and make sure I was just as light footed for both regular and premium tanks and the mileage was the same. On other tanks, I tried driving it hard and could notice no difference in performance.

    FWIW, I remember somewhere back in my mind that I read somewhere that unless your manual states premium is required, you should use regular. That same reading also mentioned premium recommended engines got slightly higher HP results with premium over gas, about 2-3%. I can’t feel that 2% so I am not going to pay for it.

  24. aloria says:

    My car’s manual calls for the higher octane stuff, and gets absolutely shitty mileage when the attendant (fucking NJ and their no self-serve BS…) accidentally puts the lower octane stuff in.

  25. deadandy says:

    This does not apply to motorcycles by the way. 87 octane gas will kill your bike.

    • Harry Manback says:

      It has nothing to do with motorcycle VS car, it has to do with each individual engine. My SV used 87, as does my XT 350, but my Sprint ST requires 89, and most race replica bikes requires 91 or 93. Read the manual, it will tell you what you need to use.

    • proliance says:

      It has everything to do with the compression ratio. Just do what MOM (motorcycle owners manual) tells you to do and you won’t waste money on gas you don’t need.

  26. d0x360 says:

    My RSX-S isnt what I would call high end but the owners manual says no less than 91 Octane which is premium. I even asked the dealer and they said use premium. I put in 89 Octane once and there was a noticeable loss in performance and the engine didnt sound very happy either. So dont use it if you want but if the book says to then you better.

  27. Andy says:

    No Sherlock.

  28. Mecharine says:

    Higher octane gas increases knocking on engines that aren’t built for high compression. High octane gas in normal engines may cause damage to the pistons, as the gas is harder to compress to reach the proper pressure for conflagration.

    • Jimmy60 says:

      Wrong. Higher octane fuel will resist knocking in any engine. It is simply harder to burn. An engine knocks when the fuel pre-ignites on compression alone. This is easier for low octane fuel as it ignites more easily. Higher octane resists knocking.

      High octane fuel can leave deposits because it is harder to burn. The engine can’t burn it cleanly because it lacks the compression needed to prepare the high octane fuel for ignition. The gas isn’t harder to compress, the engine simply can’t compress it adequately.

  29. Andy says:

    detergents in your fuel = liquid that doesn’t burn. How is that possibly better for your car?

  30. Mike says:

    The “don’t use high octane fuel” is a dangerous headline I see far too often. You really need to know what your cars needs. Compression ratios etc, influence what kind of fuel you need. Take the car used in the picture of the article. Those old Porsche 944s were designed to take any fuel, however when you used lower octane boost was reduced and you lost power. Sure, it would run fine, but come on, if you are driving a Porsche do you really want your boost reduced?

    TL;DR: Follow your user manual.

    • headhot says:

      I have an ’84 944, non-turbo. The ignition computer in that car is super primitive. I don’t think it will compensate for pre-ignition. The compression ration is 9.7:1 (even higher for the turbos and the S) I believe it calls for 91 octane (US). Europe uses a different octane scale, so you have to be careful to do the conversion correctly.

      Also, as engines age and collect deposits, the deposits (like carbon) can heat up, causing pre-ignition, older performance engines that have not been well maintained will run better on higher octane.

  31. nneul says:

    What about places where 87 and 89 are the same price? This is very common in areas of Missouri.

    Due to the lack of appropriate markings (they removed the requirement to mark content a few years back) I don’t know the ethanol percentage of the two mixes.

    Given that, is there a benefit one way or the other?

    • Zowzers says:

      not really. its all about whats required by the engine based on its compression ratio. So if your car doesn’t need a higher octane then running higher octane isn’t going to give you much.

  32. mknoll1 says:

    Not to be too nitpicky but the picture of the car being filled is a Porsche (looks like a 944) and does require 91 octane gas. It says so right inside the fuel door.

  33. Jimmy60 says:

    Simple. Use what the manufacturer recommends (assuming no modifications have been done).

    Using too low an octane can cause knocking and potential damage. While a modern car will start retarding the spark timing to compensate if it manages to not knock it will lose performance.

    Using too high an octane will rob your car of power and waste money. The motor may not be able to burn the higher octane cleanly. This can actually leave deposits which will effectively raise compression and require a higher octane fuel. Many people don’t realize that high octane fuel can result in damage in the wrong engine.

    Your car will run cleaner and more efficiently on the proper octane fuel.

  34. jvanbrecht says:

    My car knows.. and it bitches like hell unless I give it the very best.. I would put racing fuel in there if it was not $12 a gallon :P My 6.2L V8 demands it.. I will provide it.

    • Jimmy60 says:

      Racing fuel?

      That’s a wide range of product you are referring too. Racing fuels are available in wide range of octanes from 87 to 123 or so. You’d still have to pick one that suited your application. There would be no benefit to C12 if your car runs on 93. It will have no power and eventually damage the motor. Unless you’ve tuned for it.

  35. Froggmann says:

    Guess my Maxima is a bit of a pre-madona. The car just doesn’t run right on 87. Now the Bronco on the other hand will run on just about anything I stick in the tank i.e. OLD gas, 2 stroke, whale spit, etc.

  36. thanq says:

    I’m putting Chevron Supreme in both my 2000 Volvo and 2000 VR6 Jetta.

    I did tests for several months where I ran regular on both and then same tests when I used supreme.

    Findings – I would reliably get better mileage out of supreme than regular. After calculating the difference in cost per gallon to purchase vs. miles per gallons usage, I found that I only saved $0.04 per month by buying regular.

    With supreme, both cars’ engines sound better and I notice slightly better acceleration. For myself, being a picky driver, it’s a safe choice.

    For someone who has an older car or likes to feel they are “paying less” or don’t care about their care – I guess regular is fine.

    Now with that being said – do remember that Supreme gas at discount fuel stations might be equal or less than Regular at Chevron/Shell! Check the octane rating before fueling up that’s right on the pump.

    If you are putting Supreme at Joe’s Discount Gas (or even Arco), you are fooling yourself.

  37. Buckus says:

    Some cars are fancy enough to know. But then they usually recommend the higher octane for max performance, but will eat lower-grade and retard the timing to accomodate it.

  38. Donathius says:

    You don’t want to necessarily recommend just getting regular. Regular does not always mean 87 octane. In some states (like Utah, where I live) regular is 85 octane, and mid grade is 87.

  39. Myotheralt says:

    If you own a car that requires high octane jet fuel, you probably can afford to feed it.

  40. donjumpsuit says:

    Every time I do this “octane math” I come out with the same reasoning.
    First, my car calls for 91, but like it is suggested in the article, I know 87 is just fine.
    However, $3 on $60 worth of gas, that you are using for the next 300+ miles doesn’t seem that terrible. That is probably why it is priced at that point, as $6 would start to motivate me in the 87 direction.

  41. s0s has a chewy nougat center says:

    I have a 2007 Honda Accord 3L V6. The manual calls for 87 (or 85 here in the Front Range), but I’ve found that it runs sweeter on premium. Haven’t noticed much of an appreciable difference in gas mileage yet (either up or down), but it tends to get going faster than it did on regular, and the engine does feel like it runs smoother, to the point where you can barely feel it when you’re idling at a light. Plus, there’s a slight boost in responsiveness. I personally like Shell V-Power (and I get a discount on it).

    That said, I could run it on 85/87. The engine is designed to feed on that without problems. But I’m willing to pay a couple extra bucks per tank to have a nicer ride (and better response time, especially in the winter). Anyway, if I hadn’t wanted at least a bit of zip, why the hell would I have bothered buying the V6?

    My cat may not be classy enough to know whether I’m feeding her ground chuck or filet mignon, but I am well aware that one is better for her (the one that’s not 20-25% fat). I’m also aware, from experience, that my car gets better performance from higher octane gas–but that I can also give it a lower grade safely.

  42. BBG says:

    The idea expressed by the quoted article that 100 octane is a ‘perfect score’ is just so, so wrong. It is, in fact, possible to have an octane rating higher than 100. It’s also possible to have a negative octane rating. The wiki article on the subject is not bad. Note that while octane has a rating of 100, it does depend on which type of octane you’re talking about. n-octane (which is just 8 carbons in a row) actually has an octane rating of -10. It’s iso-octane, which has a branched structure, that has the 100 rating.

    Also note that gasoline is a witch’s brew that can contain more than 30 components, depending on the refinery and time of year.

  43. Minj says:

    The 944 Turbo in your lead picture certainly won’t be happy with low octane gas. Were you guys just trying to be ironic?

  44. Jemaine says:

    Okay, so… will a lower octane actually mess up the engine, even if the manufacturer recommends a higher octane? I’m not concerned about the MPGs just if it will tear up the engine. I know some people say that if one puts in a higher octane in a car that recommends a lower octane, it seems to perform better, but with gas prices like they are, the cheaper the gas the happier my wallet is.

    • buggurl says:

      Do you really want to try and experiment with your means of transportation if money is tight? I have an ’05 Turbo Beetle, which calls for 91 or above, and that is ALL that I have ever used in it. When gas prices went into the stratosphere after Katrina, it was verrrrry tempting to go with a lower octane because of the price. However, I figure that the manual said 91+ for a reason, and with the drain on my wallet at the gas pump, I surely did not need to pay for car repairs on top of that. 106K miles and still running strong…

  45. tbail25 says:

    I beg to differ about my car. Put regular in it instead of premium like the manual recommends, and it runs like ass.

  46. headhot says:

    If 100 is a perfect score, why can I buy 110 racing fuel (for my race car) Live cheap is a tad off.

    Also, depending on the car, you can actually get better mileage with higher octane. Low octane can cause pinging. When modern cars detect pinging, they retard the timing, causing a loss in combustion efficiency, which in turn causes a loss of power, which leads to worse fuel economy.

    • physics2010 says:

      Because the perfect 100 score is based on a specific iso octane combination and all rating are compared to that reference. Different hydrocarbon combinations could have a higher octane value, but they are all compared to the same reference point.

  47. elkhart007 says:

    it isn’t the pressure that’s generated when the cylinder compresses the mixture in the cylinder. When air is compressed it gets hot. High performance engines have higher compression ratios therefore are more prone to pre-ignition and call for higher octane so the fuel won’t ignite until the spark plug fires. Lower octane fuel is not inferior fuel. Ethanol blends are inferior because there is less stored energy in a gallon of ethanol than gasoline. So when it’s blended there’s less energy therefore less power and less mileage. But getting a marginal increase in mileage isn’t worth it because there are so many factors that go into mileage. This was shown on Mythbusters. Even if you think you drive the same everyday you don’t. Air temperature, road temperature, tire pressure, brake drag, any number of things can change your mileage over a tank of fuel.

  48. Mekanix says:

    This article is both right and wrong. Using premium will actually improve your mileage these days.

    Its due to mixing with ethanol. Regular is usually 5-10% ethanol in modern day. Premium gas doesn’t have ethanol mixed in at all. Since ethanol doesn’t have as much stored energy as gasoline, your mileage will drop. Of course the differences will show much differently in different engines. A lot of newer cars are built to handle a 5-10% mix of ethanol.

    If you have an older fuel injected pre-ethanol mixing era car, I would definately always fill with premium regardless. You end up saving the extra money in mileage.

  49. sunnypies says:

    “But unless you drive a high-end vehicle with a manual that specifically recommends the higher-octane fuel,”

    So I have a low end vehichle (95 V6 Camry) which the manual recommends using the octane level that falls in the Gasoline Plus unleaded section. Should I keep using Plus unleaded?

  50. comatose says:

    yeah, I actually need higher than 93. Chipped + extra boosted (21PSI BABY! – stock is like 14)

  51. gurupitka says:

    What is this “High Octane” you speak of?