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Is Costco Gas Quality the Same as Exxon, Shell and Chevron?

By , April 22nd, 2014 | 93 Comments »

There are many reasons to love Costco. They treat their employees much better than many businesses, and they have competitive prices when it comes to the things that they sell. While there might be some reasons that you wouldn’t want to shop there, a lack of quality in the gasoline they sell is not one of them.

If you have ever driven by a Costco and looked at the prices at their gas stations, you know that they can be significantly lower than gasoline prices anywhere else in the area. All you need to do is look at the long line of cars waiting to fill up their tanks to know that the price is significantly lower than most other places in the area. The prices can be so low, in fact, that you might wonder about the quality of the gasoline. When Costco is selling its gasoline for so much less than the competition, is it the same quality as brand-name gasoline such as Exxon, Shell, and Chevron? Most people want to know if Costco gas is good quality fuel.

The first thing that’s important to note is that the government sets fairly stringent standards for all gasoline that is sold in the United States. When it comes to octane level and other specific gasoline characteristics, all gas is basically the same. The difference between the fuel that you buy at branded gas stations comes down to the detergents that are added to the gas.

Even here, the government sets standards. The federal government has required since 1995 that all gasoline which is sold in the US must contain a certain amount of detergent additives. These additives are Environmental Protection Agency (EPA) approved, and the government has specified the amount of detergent which must be added to keep vehicle engines free from deposits. Costco gasoline meets all these requirements, or it couldn’t be sold in the United States.

The question then becomes, just because Costco meets the minimum requirements, is it still as good as other brand-name gasoline? A number of automakers made the decision that the US government additive requirement wasn’t high enough for many cars. As a result, they developed a “Top Tier” standard. In order to meet the “Top Tier” designation, the fuel sold at the gas station had to meet additive requirements higher than is required by the US government. Costco fuel meets this top-tier standard.

Is the gas that they sell exactly the same as the major brands? No. But no major brand sells the exact same fuel. Costco gasoline is rated as equal to any other major brand gasoline. You should not notice any difference when filling up your vehicle at Costco as compared to other major brands of gasoline. The only difference you should notice is the significant savings that you receive when filling up your car there.

Even if you feel that the gasoline isn’t quite as good as another major brands that you have used, you might want to try this “gas hack” that will still save you money. In most areas of the country you can fill up at the Costco gas station, plus add quality fuel injector cleaner. If you add this fuel injector cleaner as recommended, you will still pay less when purchasing Costco gas, and the fuel injector cleaner, than you would by purchasing gas alone at a major brand gas station.

In the end, there is nothing to suggest that Costco brand fuel is inferior to any other brands of gasoline. Don’t let the price alone dissuade you from getting a great deal.

For more info on Costco check out these articles.

Is the Costco Membership Fee Worth it?

Is a Costco Executive Membership Worth the Price?
Costco Gas Calculator: Will I Save Money Buying a Membership if All I Buy is Fuel?

Costco Return Policy

Costco Holiday Schedule

Costco Tires


You can check out our articles for Target as well.

Target Christmas Store Hours

Target Holiday Schedule and Store Hours

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  • joe says:

    Thank you for this informative article. I have wondered about comparison with other gas suppliers and this gives me comfort.

    • Vincent says:

      Idrove from Bakersfiled to Santa Nella using every gas brand and octane. Chevron, mobile, and texaco medium grage Averaged 280 a tank 12 gallon.

      Costco, Shell,Valero,Exxon, 76, Averaged 240 on Medium.

      AM/PM, and cheap discount places Averaged 220 on medium.

      Lawn mowers, tillers all start on one pull with Chevron Medium Grade.

      Its all I use or recommend now!!!!

    • Lsa196 says:

      Actually Costco is on the list of licensed brands of Top Tier detergent gasoline. These Top Tier retail locations must meet the high standards of Top Tier Gasoline to be sold as such.
      There’s a difference between the high standards of top tier and that of gas having the minimum additives of lower standards but still falls under the guidelines to be sold in the US.
      Something else to consider is running top tier gasoline in your vehicle may be more of a factor if you have a turbo engine.

    • Jonathan says:

      Well, one thing I have noticed is that recently when I fill up at Costco my engine check light comes on. Then after couple of fill up at the brand name stations the light goes off. I don’t regularly fill up at Costco, so it has been easy for me to notice the trend. Last week I filled up at Costco again but I filled up with the premium grade thinking that perhaps lower octane was the reason. Within couple of miles of driving my engine check light came on. After driving a day or so topped up with 6 gallons of premium shell and my engine check light went off in a short drive. So, I am convinced that there is something up with the fuel from Costco.

      • Freddy says:

        Same here. I am hoping my check engine light turns off after refueling at another gas station.

      • Michele says:

        Ditto with check engine light on 2010 Lincoln MKS- I will never buy their gas again

      • Geoff says:

        What code was triggering the light?
        I’ve FREQUENTLY fixed check engine lights (P0440 is a common code) following fills on my, my wife’s, and friends’ cars

        In all the cases, removing and retightening the gas cap caused the light to go away, and after clearing the code, the problems have always disappeared.

        On top of the repeated tests that have confirmed Costco gas is equally entitled to qualify as a “Top Tier” gasoline, I’m unaware of a code that would occur because of a quality deficiency in the fuel.

  • Andy says:

    I have been told by those that drive trucks full of gasoline and deliver it to the different stations that it is all the same. Every company does not have it’s own refinery, but all companies use the same gas from the same refinery which goes into the same trucks and then is delivered to all the stations.

    An interesting question to ask would be has anybody ever seen a scientific study proving that one companies gas is better than anothers?

    • Praising Costco says:

      That is true, however as a seasoned costco member and a 2013 hired employee, quality of all products has always been a concern and a personal mission of mine to research. Rest assured once the gasoline is onsite it becomes a top tier gasoline ( a Kirklands Signature ) and no longer generic and yet another genius process that sets Costco apart from the rest.

    • noah says:

      Yes they do all deliver the same base fuel as addattives are usually added and mixed at the retail station, the addatives are what distinguish one brand of gas from another.

      • Doo-dah says:

        It’s spelled additive and it is added at the terminal not the retail station.

        • QT says:

          Doo- Dah
          This isn’t a class rm. if you feel the need to be superior go back and teach second grade. Douche- bag.

          • ab14 says:

            lol how old are you, still calling people “douche bag” as a comeback

          • Marc says:

            @ QT
            It is obvious that YOU are the one who should go back to second grade, but as a student! You have a LOT of learning to do before you are a decent and courteous human who can get along with others. I wonder what ever happened to some commentators and people like you who fail to grow up and somehow missed learning the basics and have ended up so obnoxious and impolite.

        • mike says:

          Costco additizes on-site, not at the “rack” (terminal). they also additize the 87 and 91 octane uels, not just the 91 like some places do.

          • fuelqualityguy says:

            Costco buys gasoline which is additized at the terminal, just like all other retailers do. Federal law will not allow self-additization at the retail station. Furthermore, almost all gasoline in a given region comes from the same terminal, so they’re all using the same base gasoline (there are of course exceptions to this, but it’s generally true). The major oil companies typically have their own detergent additization system at the terminal which makes the fuel different. Other marketers sometimes have their own as well or use a generic additive that the terminal offers. When I worked for a major oil company in Chicago some years ago, Costco was one of our good customers and always bought gasoline from our terminals with higher levels of additive. They have some of the highest quality best practices around: they use the best filters and proactively change them out; monitor their tanks for water and cleanliness regularly, removing it if necessary and as a result, are one of the best fuel quality companies around. I wouldn’t hesitate to buy Costco gasoline or diesel fuel and I’ve been in this business for 37 years.

    • Jim says:

      I’ve enjoyed the discussions on this post, and would like to clear up a couple of points:
      1-All retail gasoline comes from the same refinery. The difference is the additives.
      2-Companies like Shell use a dedicated truck to deliver the fuel from the refineries. (Usually contracted from a local deliverer.) Before the truck leaves the refinery, a Shell employee will pour 2-4 gallons of their additive into the fuel tank. By the time the truck gets to it’s first station, the additive will have mixed evenly through the tank.
      3-About 5-7 years ago, Costco decided to upgrade the quality of their fuel. Because Costco doesn’t have a lot of stores, they don’t hire a dedicated truck to deliver the additive. Instead, they have an onsite pump that injects the additive with the fuel.
      4-The name brand fuel companies (Shell, etc.) are constantly experimenting and changing their additive formulation. This means that what you put in your car today is different (and hopefully better) than what you put in your car last year.
      5-Time of day/temperature has very little impacted on the density of the fuel you get at the pump if the tanks are below ground. This is because the below ground temperature is stable, and is about 3-months behind the above ground temps. Above ground tanks are more susceptible to temperature fluctuations, and could result in a higher density of fuel in the early mornings.

      My qualifications: I am a former petroleum manager for NATO troops in Afghanistan. My training includes refinery operations, inventory management through temperature controls, and retail operations.
      I have kept this post simple by leaving out issues like: Summer vs Winter Fuel, fuel agitation, flash point suppression, premium vs regular, etc.

      • Joe says:

        Thanks for the info. Could you write a note to further explain the items you left out. I appreciate the info.

      • Jim H says:

        Jim, Thanks for your comments which I find to match-up fairly well with what I know about gasoline.
        What you omitted is that when gasoline is delivered here in So. California (where during the most of the year, we have warmer temps than most other states) the outside temp, when delivered, is definitely taken into consideration, just because of because of “the density of the fuel”…
        That said, I agree that once the fuel is in the ground for a few days it become much more stable…but, our ground temp is warmer that most other states.

        • mike says:

          costco fuel doesnt stay in the tank long enough to get warm. the veeder root tank monitor readings show the 87 and 91 are always cooler than the diesel and the additive tanks.

      • Kimberly Fraser says:

        Jim,many thanks for all of you information which is really informative.
        Not to mention, Thank you for your services with the NATO Troops!
        Could you tell me what brand name gas station would you recommend that would be best for me and my “1995 Mitsubishi 3000GT SL” that requires 91-93 octane? Also, with the higher octane, should I uses an additive such as Techron or BG44K when filling up my tank every month? Looking forward to hearing back from you at your earliest convenience. Till then, take care and be safe..

      • Kimberly Fraser says:

        Good evening Jim, many thanks for this information, not mention Many Thanks for your service to the NATO Troops!!

        I hope you can help me to decide on what is the best of gas stations (Brand names, Shell/Sunoco etc.) to help me and my 1995 Mitsubishi 3000GT SL that requires 91-93 octane fuel.

        Also, should I put Techron or BG44k or any other additive in my tank before filling up every month to help with pinging? My baby only has 55,589 miles on her.

        Looking forward to hearing back from you with any information you can give me at your earliest convenience.

        Till then, take care and be safe..

        • Kimberly Fraser says:

          Sorry Jim, I just signed up on this site tonight and the sign up was a little mixed up and thought they deleted my first first response, obviously not. Sorry for the same second reply. Either way, many thanks..

        • First off, nice car. My brother has a 1994 3kgt SL. Second, it doesn’t require premium gasoline. That’s only needed for the VR4’s. Third, being fuel station loyal isn’t worth the energy. Most fuel gets refined at the same refining centers and your car doesn’t know the difference between Shell from Sam’s Club. Fourth, 55,589 miles – good for you! Keep her cherry! I’ve used BG44k. It’s a really good fuel system cleaner. I did notice a difference after running it in my 2g Mitsubishi Eclipse. But it’s expensive. I would limit it to every few years, honestly. Your fuel system will not get too dirty with the few miles you put on it. Fifth, that pinging you’re referring to is probably lifter tick (if it kinda sounds like a sewing machine). It’s very common in 3kgt’s. You don’t have to worry about it. You could try running a larger oil filter or running thicker oil if you really hate it. But me personally, I would just leave it alone. It’s just a little quirk of the car. Let me know if you have any other questions.

      • SHER says:

        Thank you for clearing up some common misconceptions. I bought a 2015 Honda pilot just about a year ago, and everyone said I should be using Shell gasoline in my vehicle. I usually use whatever is closest or the cheapest. There is a Costco right down the street. I feel better knowing I can use their gasoline comfortably. Thank you, Jim!

      • aaron says:


        if I can clarify a bit:
        1. I think what statement 1. means is that base fuel from any refiner is the same. whether it is an Exxon, Valero, Conoco-Phillips/Phillips66, chevron, etc the octane, Reid vapor pressure, detergents, etc all meet the same specs. if a company does not have a refinery in the area, they buy the base fuel from distributors and modify to individual specs. Yes the difference is the additive package. But different additives affect the fuel combustion profile differently…some provide more octane boost early in the combustion cycle vs later in the cycle.
        I am a chem engineer who has worked for a couple of the above mentioned refining companies.

  • Gas price is one of the major problems in our country. The gas hike continues to rise almost every week!

  • Earl Richards says:

    To avoid the gasoline price rip-off, plug your Tesla S electric car into your household, solar array.

    • brad says:

      Except that it has been computed, many times, that the excess purchase price of those vehicles, when extrapolated using non electric cars in comparison, end up costing more. (With the exception that if you keep the car more than 7 years, then it will cost less overall, than a standard gas vehicle.)

  • mom-from-missouri says:

    Interesting. First husband and I owned several gas stations back in the 80’s thru 2008. We changed branding several times–Phillips 66, Conoco, BP. Yet, it all still came from the same supplier–Carter Petro….same truck same delivery driver….
    He would top off our tanks then drive down the block and top off the next stations tanks.
    It is all the same stuff.

    • Yeah boy! says:

      Mom’s comment is probably one of the most valuable in the discussion of gasoline quality. First hand, real world consumer type of comment. Scientific and brand-biased comments don’t really help when we just want an answer that cuts to the quick. No clutter. No confusion. Thanks, mom-from-missouri.

      • saikanomie says:

        Thank you mom. I would go Costco from today, and perhaps add my own additive from walmart.

        Octane booster

  • Praising Costco says:

    The process occurs onsite at each gasoline drop and at every Costco gasoline fill up site and that is where additional detergents while closely monitored by EPA are added. I am sure Costco has invested a lot of $ by doing this however as you can see it apparently has paid off. I am a costco employee .

  • michael reed says:

    I work for costco In eugene oregon and was a gas station employee. Costco gas is truly everything they say it is and the additive we add with every load coming in is truly top quality. Costco is all about value and top quality products and I’m proud to work for a company that treats it’s employees so well. A+

  • Carrie says:

    I beg to differ. I love Costco, I shop there weekly but several years ago I had many car problems. My car was at the dealership week after week thankfully all covered within my 36,000 mile warranty. It was later discovered that the cause of the nearly $5000 of damage to my 3 year old car was Costco gas. Once I stopped filling up at Costco I only went to the dealership for regularly scheduled maintance. Many dealerships such as Mini Cooper reccomend to their customers that they not use Costco gas. I assume BMW says the same since they own Mini.

    • JB says:

      I had the same problem with my BMW 745. Warranty repIred at 5,835. They also told me to stay away from Costco. All i ever used is premium, even at Costco. It took about 3 monyhs and my troubles began.

    • Vv says:

      I also like Costco and frequently shop there. However, I stay away from their gas stations. My 2006 Nissan Altima started giving 19 mpg on highway which should be 27 mpg under standard operating conditions. Engine vibrations also increased significantly and the drive got rough overall. Once the “check engine” light turned on the first thing I did was changing the gas company. Within two days after changing my gas, the “check engine” light went off and the gas mileage also improved (27.7 on hwy, 25.4 city). It runs smoothly as it did before I became a Costco member and started using their fuel.

      • LCH says:

        Both my husband I started buying Costco gas around the same time. We have a Chevy Truck, and mini van. Both started having engine problems around the same time, and my husband, who is very knowledgable about cars, and repairs ours, believes it was the Costco gas. There is something different with this gas that causes problems! We no longer buy their gas, and have had no more problems.

        We figured out that by using the Exxon Mobile gas card with 6 cents off per gallon, plus some of the Mobile stations give you the cash price with the card, so that’s 16 cents off per gallon – better than Costco and no lines! 🙂

      • ab14 says:

        Your CEL probably came on for a gas cap evap failure. I was driving to the vet early and got a CEL in my Is300, pulled the fuel cap, gasket was good so I put it back on (like you do at a gas station when you’re done fueling) and after the cars computer retested the evap system the CEL went off. I don’t blame the vet and ive never had any issues with my cars at Costco, not my Honda, nor my Lexus, not even my Ford. I think a lot of you have other issues with your cars and should invest in a set of tools and do some homework. Gas is gas and if you don’t maintain your car its going to stop getting good mpg, and its going to get deposits. I haven’t heard of fuel causing a CEL and I work in the automotive field…

      • ab14 says:

        Im interested to know what code your CEL came on for.. never heard of gas tripping a CEL

        • wstrnrefinerysucks says:

          Clogged fuel filter in my Tahoe . . . also, clogs the fuel injectors to the point I have to put an additive in the gas tank. Chevron, Phillips 66, or Texaco do not cause the problem in the least.

    • Roam says:

      First… Getting repairs done at any car dealership is a rip-off, they overcharge on everything (parts & labor). It is only worth going to the dealership for repairs as long as your warranty covers it all.
      Second… You get what you pay for. Generally cheap gas is low quality, when it comes to cleanliness.
      Examples: Shell gas is rated the Cleanest gas in the USA, by the EPA. Some Sunoco stations sells the highest octane, which means you get more power for the engine (basically it is the lowest of racing-fuel that is street-legal). BP has a higher Ethanol% than other brands.

  • MikeH says:

    The worst Gas in AZ and you can tell from 1 fill up. is AM PM…. I do not notice a difference between QT and Costco, but sad to say QT is same price usually and NO Lines…. Would love to go costco more,,, but I leave for work by 5am,,, Costco CLOSED, QT is open,.,,,

    Next other time,, you already have a self serve,, make it open 24 hours… Duhhhhh

  • Doreen says:

    Just recently costco now sells tier 5 gas which is higher than chevron or shell based on additives.

    • Ron says:

      Top tier has NOTHING to do with additives other than detergent. Chevron Techron and Shell V Power are separate additives on top of the standard Top Tier level detergent. Top Tier mean detergents higher than the government’s minimum requirement are used. All the major station are now Top Tier including Texaco, 76, Mobile, Arco. That means even the ethanol using station are using such detergents.

  • Holly Nelson says:

    Might want to reconsider Costco. Are you Pro-America like the rest of us, or Anti-America like Costco?

    • ab14 says:

      you should reconsider all the china made junk sold everywhere and the places that hire illegal immigrants to cook and clean, there’s a guy that tries to protest Costco fuel, the genius drives a eropean car. he must have gave up though cause I never see him and im there every time I need fuel

  • Merica! says:

    Holly… don’t be a troll.

    I stand for American Workers, and that’s who Costco takes care of.

  • Scionxb12 says:

    Kirkland Signature gasoline, is the best possible gasoline money can buy. Gas is all purchased from the same suppliers but then they add 5 times the epa regulated detergent to their gasoline a major benefit for their members. Costco has very strict regulations on their gas they change their fuel filters more frequently than all other stations. Fuel filters are just like oil filters trapping sediments and particles and need to be changed every two months to ensure the cleanest product. Peoples comments are so funny on here the whole BMW’s malfunctioning due to Costco gas is a joke. BMW just wants to point the finger at someone else when everyone knows there cars are overpriced maintenance prone. If their gas was so bad why would they be praised Ford and GM that makes no logical sense. M.y mileage with ks premium improves 4-5 mpg city and 6-8 highway. Costco has the cleanest station around in my town. Even after storms they are out there making it sparkle. My rule of thumb for gas is if the station is dirty I wouldn’t trust the product but if it’s immaculate you can bet the product is just as clean.

    • Cindy says:

      can too many additives cause issues? My car never seems to run as well on Costco gas as it does on other brands. Maybe I’ve just had bad luck?

    • Martin says:

      I work at costco and theres no filters at the gas station that get changed. I know cause I used to work at the costco gas pumps.

      • SueintheSun says:

        Costco employee here in Anch says: YES filters at station, changed twice per year. Also appears employees are split between Costco vs. other (mostly to all Chevron gas.) Costco Station employee says he uses Costco, and that if I want to add Chevron injection cleaner, can get at Costco a year’s worth (I had read that elsewhere, keeps costs down.)

    • MightyMouse says:

      Check out the new Shell V-Power Nitro+ fuels. The only fuel recommended by BMW M and Ferrari.

      Best fuel out there right now IMHO.

      7 times the cleaning agents, plus several other factors are much better.

  • Oz says:

    In summer this year we bought two new cars Lexus E350-2014 (wife) and Infinity Q50-2014 ( me). Both are rated at 20miles/galon for city drive. We use Costco premium 91 gas in both. In practice Lexus yields about 18.9 miles/g but so far Infinity Q50 yields only 15.3 m/g. I reprted the disappointing milage to the service manager. She suspected gas brand and advised not to use Costco gas (old gas ?). I do not understand it since Lexus E350 milage is close to stated rating with the same gas brand. Both cars are driven in the same city and route. I wonder if Infinity has over stated its fuel economy similar to reported reported in news about an other car maker. Infinty Q50 is a new model that came out in 2014 so there is no prior history of fuel economy.

    • The coke guy says:

      I’ve owned Nissan Infiniti Mazda Ford and Scion. And I am hear to tell you the Infiniti and Nissan (same company) are never close to what they say on the mileage. Idk how they test but it’s about 7 miles off what the say

  • Jose says:

    We have a 2011 Ford Explorer and i have been using Costco gas exclusivley. Im averaging 17-19.4 miles on the highway communting work. We averaged 24.9 when we traveled to Santa Barbara and Monterey, Ca. We stopped at a few at Chevron stations ( 2nd choice) and i found both give me the same results. So far, i have been happy with the quality of gas from Costco. Im really picky and i meticulously take care of both my car and my wifes honda Civic.

  • JamesG says:

    I’ve been running pure Costco Gas on my 2014 Mazda6 since day 1, when I bought the car. No other gas station brand. Be it regular or premium Costco gas I use (premium is now only $2.74/gal, as of this writing) as my car’s direct injection engine was originally designed to run on premium (slightly better level of detergents). Costco gas is Top Tier gas and runs perfectly on my car. Being knowledgeable on cars, and as a preventive maintenance, I pour a bottle of Chevron Techron DI cleaner twice, every 5,000mi, since the car’s mileage hit the 10,000mi mark (also from inside Costco). I have no problems at all, since Day 1 of Costco Gas use on my Mazda, whatsoever.

  • Lexie says:

    Since gas has dropped below three dollars I filled up my tankwith Cosco gas which I always buy. However my car gas mileage average suddenly dropped from 22.5 around town to 17. What is with this?

    • douglas says:

      If you have always bought it in the past and it just dropped this last time, you need to take your car into the mechanic. It’s likely there is something wrong that made the gas mileage drop.

  • brad says:

    While this article is “generally correct”, it errs in that I ALWAYS find a local retail station at the same, and usually, lower price as Costco. Usually, but not always, ARCO.

  • Brian Turner says:

    Today I bought gas at the Simi Valley, California Costco. I could not start my van after filling up, despite many attempts. I thought it was vapor lock. So I removed the gas cap. Then my van started. Later that day after using up most of my gasoline, I attempted to start my van. Usually my van fires up instantly. But again I had trouble starting it. I drove to Shell and filled up. And presto, my van fired up immediately. VERDICT: Costco gas has way to much ethanol added for current vehicles, and should not be used!

    • Justin says:

      You do know that when you fill up the gas you just put in the tank is not going to be the gas that goes through your fuel pump, through your lines, and straight to your engine? You still have residual fuel in your injectors, lines, and fuel pump from your previous fill up. You most likely have a separate problem with your vehicle and should have it checked out.

      • Person says:

        well if he fills up .. after being empty… he could just run the van for like 2 mtns and then the new gas will be burning already

  • konrad says:

    Time will tell… jist fueled up a 95 crown vic and i could only pull 325km out of it with costco fuel… where as with petro i get a minimum of 500 in city… fueling at petro today we will see in a week if the car has aged horribly or if there cutting corners.

  • Mary says:

    I’ve always found the Costco gas quality to be the same as the top name brands of gas. Shell, Exxon, Chevron, BP. I keep a log to track the mileage of my car and there is no difference when using any of these. Since that’s the case, it makes sense to choose the gas that is the least expensive to get the best value.

  • ColoradoRick says:

    I have long been a Costco member and use their gas for a Honda Accord, and VW bug, and my Range Rover. I started having issues with the Rover. I changed brands on the Rover and the issues went away. Not sure why it started having trouble but it definitely seemed related to Costco gas.
    The Honda runs fine but knocks on occasion, when that happens I just put a tank of some other brand through it and it clears up. Strange.
    The VW seems just fine with the Costco brand.

  • Lanna says:

    Why do so many people seem to think that Costco gas is worse than other gas? It’s all the same stuff, fools. The only difference is the detergents in it. If your car runs badly on Costco gas, it’s the car’s issue, not the gas.

  • Tauna says:


    As each car is different check your MPG. I don’t go to Costco because I loose 3 MPG while driving,or 30 miles per tank. I check different stations to see what fuel gives me the best mileage per gallon; Costco gives the worst MPG in my Hyundai.

    • Person says:

      its exactly what i do, but given the fact that if i fill at shell (which gives me more mileage but at a higher price) than just filling at costco and pay less… its kinda even to fill either at costco or at shell.

  • James Adduci says:

    My question for Costco is, “How much ethanol is in Costco gas?
    The reason I am asking this question is because I was just given a 1977 Honda Goldwing motorcycle that is beautiful, but not running very well. I did some research on motorcycles and the new fuels with ethanol in them and it doesn’t look to good for any motorcycle. It doesn’t appear that the motorcycle manufactures have stayed up with the automobile manufacturers in preparing their products for the use of E10 or E85 gasoline. Also, these new fuels with ethanol in them need to be used at a fairly rapid rate or they deteriorate in power and sometimes separate in the tank under certain circumstances, such as in the tank of a motorcycle that is only ridden infrequently, like I do.
    Can you elaborate on this problem? It sounds like our government is interested in cleaning up the environment, which is good, but many motorcyclists are going to be upset when they find out why their bike is not running very well.
    Jim A.

  • gary says:

    I had been a loyal costco gas customer until three weeks ago. within less than 100 miles of filling up at Costco, my car would not start and had to be towed into the dealer. After inspection it was determined that the fuel filter was so clogged nothing would get thru. After replacing the filter and cleaning the injectors we were back on the road. According to the service tech, he’s seen several cars come in on a hook after purchasing gas at Costco and he recommended steering clear of them and other low end suppliers. The couple pennies you save aren’t worth the inconvenience of having the car towed or the risk of engine damage.

    BTW, we spoke with the manager of the store where we used to purchase gas and he was “shocked” that we had a problem, since he had never heard any complaints before. We also filed a claim with Costco to cover the towing and repairs but were summarily denied.

    Lesson learned.

    • Person says:

      You cant really prove that costco gas made that damage…. unless you can then filter ur gas you pump every time into a bucket and then make sure there is debris on in right off the pump.

      Gas Filters fail too… fuel pumps can pass debris too… you supposed to have a filter inside your fuel tank too.

  • Person says:

    Personally, i stick with shell when there is no costco nearby or they are close (because they are dumb enough not to have late hours at their pumps) jk …

    Whenever im broke or there is no top brand around.. ill pour in valero or arco … and boy it makes a huge difference you can totally make the test your self .. i mean just for the sake of your vehicle.

    Try driving empty to you favorite gas station (whether its cheap or expensive) to fill up a few gallons then drive of to u can tell u have spent those few gallons.. but meanwhile notice your engine power, speed and all that and of course your mileage… then do this as many times as possible with the same weather and road conditions and you can easily compare how cheap… means cheap.

    Then will stop wondering if really shells price its worth those 10 extra miles you can get out of filling up with them but that arco doesnt seem to work well on your engine.

    Personally costco is not top brand .. i get less millage when filling with them … but the price difference its pretty much as if you would fill up the tank with shell

    Engine wise.. costco premium feels good on my engine. doesnt shake like arcos or valeros gas.

  • Margaret says:

    I came upon this website because I just bought a new car -have 900 miles now. My Subaru Impreza says it will get 28 city/ 37 highway mpg. I’m getting about 23 mpg and on my 3rd tank- all from Costco gas stations. I purchased the Impreza over the Forester (my last vehicle) because I normally do a lot of highway driving (but not since I purchased the car and the Impreza had the best mpg, an important feature when I can drive 90-140 miles each way to work.
    When I took my car in for some post purchase upgrades and mentioned the lack of mpg and the difference- the service manager asked if I used Costco gas and that I should switch for a tankful and see what happens. I haven’t so far but wanted to see what others had to say first and if there was a real difference.

  • Justin says:

    My wifey has a 2009 VW Jetta. It has 38k miles on it and has been well cared for. We run a bottle of Techron through the tank every 6 months. We recently had a few codes on the Jetta for sensor failure (VW sensors love to fail randomly). There were a few other codes related to carbon build up so we had a fuel system cleaner (at dealer because sensors were covered under extended warranty). My mechanic had just installed a new fuel filter and he stated that it is a good thing I came in a little early as the filter was starting to get clogged. Both the mechanic and the VW tech (not the service person) stated that Costco gas is no good.

    I had previously researched Costco gas and found that it was a Top Tier gasoline. Basically, this is my take. If you switch to Costco, the added detergent will clean your engine. That cleaned gunk needs to go somewhere. I think it is something similar to the people that have trouble with Seafoam. The product works, but sometimes has unintended consequences. My theory is two fold.

    First, the extra detergent breaks up gunk in the tank and such and that causes fuel filters to get clogged. Since most people do not change their filters, it only compounds the problem. The extra detergent may actually not be a good thing. Also, due to the differences in fuel systems between makes and models, the root cause is probably difficult to locate.

    Second, I believe people’s driving habits make a huge difference on vehicles. For my wife, we make frequent trips of under 3 miles. The Jetta rarely gets a chance to warm up. We are one of the few people an electric vehicle would make all the sense in the world to. I believe that the frequent short trips lead to incomplete combustion and aid to the carbon build up in our vehicle. That would also explain why some people driving the exact same models of vehicles have problems with Costco gas and other do not. I also believe this is what causes some of our premature sensor deaths in the Jetta (although this did not happen in our Ford Focus in 40k miles of similar driving and over 100k miles total). Maybe the extra detergent has something to do with this?

    • Get that woman a bicycle!!! Yes, driving too few miles leads to all sorts of finicky problems w/ internal combustion engines”

      1) Batteries fail because they don’t have time to get fully charged back up by the alternator
      2) Exhausts rust because they never get hot enough to burn off the condensation, thus the water just sits in the exhaust bends
      3) The problem you mentioned
      4) MPG is horrid since engines burn a lot before getting up to temp
      5) There’s another problem with the engine oil. I don’t recall what that is at the moment.

      You should convince Consumer Reports to do an investigative study about detergents. Or if they already have, they need to get the article SEO optimized for Google. There’s no good piece advertised about the ill-effects of Costco fuel.

      Although even if it does cause sensor and fuel filter issues to some cars eventually, the engine is still getting cleaner. And combine that with the fuel cost savings and you’re probably still coming out ahead pumping Costco fuel.

      Seriously though, get a bicycle! They’re great for short trips!

  • Roland M says:

    Costco gas is not worth it for me:

    (1) I can get gas cheaper from a well-known retailer(after an immediate savings) via their credit card.
    Costco has a cash back savings credit card as well, but it doesn’t compare favorably to my savings.

    (2) Avoid ridiculous line ups. Time is money.

  • Bill van says:

    I own a Lexus LS400. It requires 91 octane fuel. When I use name-brand gas e.g. Chevron, Arco, Shell I get 32 mpg on a specific freeway strip. When I use Costco’s supposedly 91 octane gasoline I get about 25 mpg. I have tried this several times, always with the same result. Maybe Costco is selling a lower octane gasoline? Is their 91 octane different from Chevron’s 91 octane. So, I have stopped buying gas at Costco, except when I rent a car that uses regular gasoline.

  • Craig says:

    There most certainly are differences in the additive packages, years ago I had a car run poorly on Arco, the a different car run poorly on Shell, my friend who used Arco, Costco, AmPm and basically anyone cheap had to have a Honda’s intake manifold replaced due to carbon build up at around 140,000. I had taken multiple cars past 150k with no problems on Chevron, Texaco, and Union 76. Thank you, I’ll spend the extra money.

  • JackALope says:

    All I know is I get better gas mileage when I buy Top Tier gas. Costco and Chevron seem to give me the best mileage. I average about 1/2 mpg better with Top Tier gas. BTW, not all branded gasoline is Top Tier (see Citgo) and several non-branded stations are (see QuikTrip and Valero).

  • Mtbdude says:

    Lots of anecdote in this thread,no science. I’ll throw in my $.02 anyway. My 2012 Acura TL accelerates like a bat out of hell no matter whose 91 octane I put in it, a and gets great or crappy mileage depending on how I drive it.

  • Dave F says:

    All I know is, when I use gas from Coastco, my F-150 does not get very good gas mileage. I usually get around 15 to 16 MPG. With some other retailers, i.e., Marathon, I get 19 to 20 MPG. I don’t drive any differently so maybe there is something better in Marathon than in the Costco gas.

  • BenG says:

    I was at the Costco gas station in Signal Hill California getting gas and talking to the attendant about these men that were doing test on the the fuel. He tells me that they are from the E.P.A. and they needed to see the purchase order from the refinery, and even to the attendants surprise the fuel was purchased from the Chevron refinery and contained “Techron” Chevron’s brand name detergent, and that the gas was passing all State standards was proven to be “Top Tier” gasoline.
    Costco gets a great deal from Chevron because they sign a contact that states that will buy a specific amount of gas guaranteed whether they sell it or not, which gives the refinery and Costco security. Costco keeps all profits at 3% or less so Members always get a great deal on whatever they buy.

  • Earthwarrior says:

    Costco adds an additive to their gas in an attempt to make your car get better mileage. It destroys the catalytic converter and eventually your engine according to my mechanic. Write Costco’s corporate office and ask them to stop. Boycott until they do

    • All about $$$$ says:

      I’ve actually used Costco gas for 8 years now and didn’t see a difference in mpg. I always got better than stated mpg. I always drove a new car though and until recently decided to hang on the my 2012 Camry SE V6. I had it 4 years and sensor lights started going off (check engine light = sensor failure code…can’t remember code). I take extremely good care of my cars and everything I own. I couldn’t understand why it would go bad so quickly. Yeah, mechanical/electrical components can and will go bad but Toyota builds reliable vehicles using quality components. But still it can still go bad. I was about to just have it fixed and decided to toss Fuel Injection Cleaner in and filled at Chevron bc I know they put “Techron” (my dad swears by this stuff) in their fuel. Didn’t expect to fix my sensor issue at all but thought I might do it bc I haven’t done it yet since I only had 31k on it after 4 years. Yes, I’m going to say that the check engine (sensor) light went off and hasn’t come back on after 4 months. Oh, and I don’t use Costco has anymore. Not saying their gas is inferior but I wonder what detergents they use?? Like someone else said, gas companies are always changing the formula. Costco isn’t a gas/petroleum company or has a background in it. They probably had experts concoct a formula of detergents that just isn’t good. Too much salt is clogging the arteries, so to say! Where Chevron uses just a pinch of salt among other ingredients. Costco needs to go back to the drawing board. Other than Costco gas, I love Costco and purchase thousands from them each year easily paying for my executive membership in rewards earned.
      Oh, when I did take it in after the light went off and explained them what I did ( I didn’t mention gas, just sensor light and injection cleaner and Chevron for the Techron) and he said to stay away from Costco if I went there! What!!! I started laughing bc I didn’t mention to him where I go for gas. The service advisor said he’s seen Toyota after Toyota come in with gas related issue as poor gas is general cause and Costco was the main culprit.
      Much goes into what’s best for this car to how you drive and how far and etc…….in the end, I use either Chevron or Shell now. Just think about what you’re really saving. Let’s say you have a 16 gallon tank and you see the cheap gas on one corner for $1.50 and the Chevron (expensive stuff, lol) across the street for $1.60. You’re thinking .10 cents, dang, I can’t afford to pay $1.60 more to fill up at Chevron. Whatever size your tank is you do the math. It’s not much at all. Forgo the candy bar, extra coffee, donut or that small want for a better likelihood that your car will need fewer repairs.
      Sorry for the long post but I reasoned with myself and found that it’s really not much at all. Just get the lower octane gas at Chevron or Shell. You might not have those two but others are out there that are better than Costco concoction.
      Next time you’re in a dealership or service department , just ask them about their recomendations for your brand of vehicle. Some vehicles seem to do better than others with certain fillup stations. I traded in my Camry for a Tundra and I still get better mpg than stated but only time will tell if Chevron and Shell keep this truck going clean. Good luck, all!

  • Eric K says:

    I have a 1995 Toyota Camry (4 cylinder) and it developed engine performance problems when I started using Costco gas. As soon as I switched back to name brand Top Tier gas my car has performed well. So yes, those additives make a difference for some cars.

    • Eric K says:

      I don’t know if Costco changed anything recently, but I tried their gas when they had signs advertising 5 x EPA standard for their additive, but the TopTierGas.com website did not list their name. Now Costco Wholesale appears (and Arco!!) on the Top Tier Gasoline website. I am very convinced Arco gas ruined the engine on a different Camry I owned. Now I’m wondering if that website is losing its trust factor. I don’t believe for a second that Arco is good gasoline unless they have recently changed.

  • Jack Smith says:

    I can only say what I have experienced. I normally use Chevron only, and have had consistent long lived engines, with no engine problems. I tried using Costco gasoline in my 1999 Buick Park Avenue. My engine started running rough, and I had the final incident where the car was backfiring, and my engine check lite came on. I went to the dealer, where there found that the gasoline was the problem. I stopped using Costco and went back to Chevron gas. The engine started running smooth again, and no more backfires, or engine check light. I also put the gasoline into my KIA, Amanti. The engine had started running rough, immediately. I stopped used Costco in it, the same time that I stopped putting it in my Buick. The gas is currently 60 cents cheaper at Costco than Chevron, but I will not use it. I value my engine, the smooth running of my engine, and the life of my engine. The Buick has currently gone 188,000 miles, using Cheveron. My previous car had gone 315,000 miles, before a cylinder finally went. I will stick with Chevron.

  • Miranda says:

    When I bought my 2012 Ford Escape, mechanic at the dealership said stay away from Costco gas because over the long haul it damaged the motor. He had no reason to gain from that comment. I’ll stay away and after reading comments here sounds like he was right.

  • JuanCarlos says:

    When I moved to Salem, Oregon in 2011 I started using Costco Premium gas on my Lexus LS 430 a few months later I started noticing some performance issue but I thought the car just needed a tune up. Suddenly I started to get engine lights and errors codes and when I took it to the mechanic I had to replace the catalytic converters and the oxygen sensors.
    One of the questions was what gas I was using and of course it was from Costco. This was a very expensive repair.
    The Catalytic rarely go bad on a Lexus.
    After the repairs I only use Chevron Premium gas on all my cars. The performance and the gas mileage has also improved.

    I love Costco but I don’t know what that hell they mix with their gas but it will kill your car.

  • CA Coyote says:

    It’s just this simple.

    All fuels categorized as “Top Tier”(TT), are good for your vehicle. These fuels are tested and have more cleaning detergent additives (then non Top Tier fuels) included in the fuel and will run for all cars here in the U.S. There are enough of these TT fuels that everyone has access to them in every state. The list of these TT fuels is on the website- toptierfuels.com. BTW, Costco is now a TT fuel (been so for the past 2-yrs.).

    Octane rating is important too. Especially, to the extent of which cars need it and which don’t. The ONLY vehicles that “need” premium (or mid-grade) fuel, are the ones whose owners manual says it does. Note “needs” is different than “recommends”. Most ‘newer’ (from 2010 and beyond and I may be off a year or two) cars can run on ANY grade fuel. There are fuel sensors in every engine that will sense the fuel grade and compensate accordingly. Now, for those that owners manuals say “recommends” a higher grade, that means you can still use regular but the higher grade will deliver better performance (better mileage and power). High performance cars (like Corvettes/Mustangs/etc.) usually have this caveat, reduced performance for lower octane. Some cars (like ultra-high performance cars, Porsche/Ferrari/Bentley/etc.) say in their owners manuals that they “need” premium fuel and MUST use it.

    Some folks continue to believe in the false information that the better the grade fuel you use, the better for your car. Totally not true. If you use premium/mid-grade and your owners manual says it needs regular, you’re wasting your $.

    That’s it.

  • Sum Yung Gai says:

    I’ve used Costco Premium (93 octane) and Regular (87 octane) gas in my Mercedes S430. My results are as follows.

    Highway-only mileage: 26 mpg on both Premium and Regular.
    Town/highway combined mileage: 18.5 mpg on Regular, 18.2 mpg on Premium.

    The difference in combined mileage can probably be attributed to different traffic patterns and differences in operator behavior behind the wheel on any given day. So, I’d say the difference is negligible. Note that M-B S430’s have their timing optimized from the factory for 91 octane.

    I did something similar with an S600 V-12 turbo (93 octane required, per the factory) on a road trip, with the following results.

    Costco Premium initial fill-up: 20.5 mpg doing mostly between 65 and 70 mph (speed limit on freeway started at 55, then went to 65, then finally 70).

    Shell Premium re-fill-up: 19.5 mpg averaging close to 80 mph (speed limit was 70 almost the entire way).

    I’m not sure if the speed difference mattered enough to make a 1-mpg difference, but I’m sure it was a factor.

    So, I’d say Costco gas is at least as good as Shell. And that’s good enough for me.



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