Why aren't anybody talking about costco gas giving very low MPG?

Posted by DavidNLBC@reddit | askcarguys | View on Reddit | 31 comments

I have been using Costco gas for decades. I have had Hondas, Toyotas, Mazdas and Nissans, and I always fill up with Costco gas. I live in Long Beach, California, where there are two Costco petrol stations. One is in Lakewood and the other is in Signal Hill. Both are labelled as top-tier gas. You would think that all the detergent additives they claim to add would improve MPG and acceleration, but this is far from the truth. Now, before you say that all petrol is the same, I invite you to investigate and experiment in the same way that I did. With every petrol fill-up from empty, I always set my trip A to 0. I drive the same destination from point A to B every single day 5 days a week for years.. Costco petrol gives awful MPG and the acceleration feels awful too. Yes, it's even worse than Sam's Club gas. With every Costco gas fill-up, I lose about 7 mpg. Add that up over 13 gallons and it makes a substantial difference to the number of miles you can drive. Sam's Club gas gives better MPG. Chevron gives the best MPG. Shell is second best. Nobody else is talking about this or dissecting it the way I am. It's just crazy, and I feel costco is taking advantage of elderly civilian citizens.. Costco gas is watered down! Please, before you flame me.... Do the test! THANKS..

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Loaf-Master@reddit

I did a test a number of years ago in my car and got 2 mpg less on Costco gas than I did with ARCO on the same weekly routes. And this is was in a Tahoe so from 13 mph down to 11 mpg (~15% loss). I’ve suspected it was too many additives in the fuel. Waiting in line for 15 minutes to save 20 cents a gallon to end up burning more was never worth getting it there again. You are not wrong and I have asked others before and they’ve noticed this as well.

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DavidNLBC@reddit (OP)

People here think we are crazy. ... 😆... I drive the same way 5 days a week... My life is boring, so I have all the time in the world to test it.. Costco gas is the worse... And chevron gas is like superior than anything. Costco gas add way too many additive which in turns burns way more gas... Is it good for the engine? Maybe, but I noticed accerlation sucks tooo.. Gas is gas and thats what the engine wants.. If I needed additives, Ill just buy 12 pack of gas treatment fuel intake system cleaner that will peobably last me a year or so..

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Conspicuous_Ruse@reddit

I don't think the rest of us have that problem.

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Ok-Confection2834@reddit

I certainly don’t.

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Winstonoil@reddit

I had a friend throwing code in their vehicle I went to read it, by the time I got to their house they had figured out that it was Costco gas making their car run bad in Canada. It’s not the first I’ve heard of it.

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DavidNLBC@reddit (OP)

People say all gas is the same... Maybe true, but when they water it down with so many additives, it aint even the same anymore... This isnt in my imagination as I have been testing this for years...

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Winstonoil@reddit

There is a current lawsuit against a gas station in Edmonton Alberta for having water in their gas. I’m sure that information is easily googled.

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fad3dm1ndz@reddit

Ayeee you're from LB too! I've done a similar test, but this was when I lived in Oregon 5\~ years ago lol.

My commute and driving habits were pretty much the same, car was maintained the same, tire pressure consistent, etc etc.

I'd test Chevron, Shell, Fred Meyer/Vons, 7-11, ARCO gas and some other cheaper chains. The best results always came from Chevron/Shell, the rest yielded lower mileage for sure. When I did the tests, I expected at least maybe a 3-5miles variance, but I'd get an extra 25-30\~ with the higher tier stuff. I did this test during different seasons too, mainly because I know summer months, the detergents and such do change.

Since then, I don't really bother with anything else. Shell is my go to station and Chevron is my back up, along with an annual dose of Chevron Fuel Injector Cleaner treatment for my cars.

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DavidNLBC@reddit (OP)

People aren't believing this because they don't even test it... I drive the same way every single day and always set trip A to 0... Costco fuel is watered down with all the supposed detergent additives they are adding.. Probably taking advantage of clueless senior citizens... On Facebook, a guy is claiming the same thing.. It is not in my imagination... And yes, I have all the time in the world to test it out..

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ppepitoy0u@reddit

All California gasoline comes from the same refineries. You should prob check your engine air filter and spark plugs if you are getting low mpg.

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Joe_B_Likes_Tacos@reddit

This is totally true. Chicago is another example. Half of our gas comes from the BP refinery in indiana. The other half comes from two smaller refineries. It's all the same gas that gets delivered through the same pipes. The only difference are the additives that can be added at the distribution points.

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NorthSpecialist6064@reddit

Terminals dont add additives. It's literally all from the refinery.

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Joe_B_Likes_Tacos@reddit

I would suggest you Google this and learn that you are wrong.

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NorthSpecialist6064@reddit

I would suggest you actually get a job and work in the industry

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lemonvr6@reddit

water is not compressible

read a book OP

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NorthSpecialist6064@reddit

You read a book, dolt. Water doesn't BURN. That's not what's happening here. Water in fuel doesn't hydrolock engines. Never has.

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Smooth_Discussion367@reddit

Costco near me sells 87 and 91. My ecoboost f150 runs the smoothest on 93. I go elsewhere rather use 91.

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New-Patient-101@reddit

Ever consider your filing ALOT more when you fill up at costcos? There is absolutely no way you’re loosing 7MPG from different gas stations. Just absolutely not. Your either letting your car idle or your really bad at math.

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Schmurtzy@reddit

Make sure you are getting Costco gas during the weeks the black helicopters are not flying with the disruptor plates.

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Temporary-Chest-3111@reddit

If you “always” use Costco gas how do you know Chervon/Shell etc is the best/better etc? How do you have a control environment for measuring fuel economy? Are you simply comparing what you get vs what the sticker of your car says? The I have news for you: the sticker fuel economy is a number obtained at the optimum testing condition and thus is not always easily reproduced.

I almost exclusively use Costco gas and get fuel economy better than what the manufacturers report, but that’s a sample size of 1, just like what your case is. So I guess the two of us cancel out then? Honestly, if Costco gas is so as someone would have already put together a class action lawsuit years ago…

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benicebuddy@reddit

You don’t though.

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Zealousideal-Goat839@reddit

This is a schizo post

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Demented-Alpaca@reddit

All petrol IS the same.

All additives are NOT the same.

I don't know what Costco adds or says they add. But additives dilute the fuel. If you add a cup of additive to 10 gallons of gas your gas is now 99.4% fuel and .6% additive.

And since the additives are things like detergents and stabilizers they detract from fuel efficiency.

You'd have to do some real world experimentation but I've found, anecdotally I get ok mileage from Costco, bad mileage from Chevron and the best from Maverik. (Again, this is just me driving my car and noticing how many miles I get from a tank at these places. It's is, in no way, scientific or accurate.)

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TellemTom@reddit

I have absolutely no difference in mpg from Costco gas.

Most gas stations get deliveries from the same trucks.

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