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Chevron vs. generic gas

Every time I have bought a new car the dealership has recommended that I use Chevron gas. After I bought my latest car, I decided to make use of the automatic mileage calculator and see if there was a difference in the milage between Chevron and the cheapest gas station in town, figuring that if Chevron really did make your car run cleaner and more efficiently, there should be a corresponding increase in gas milage.

Consistently, for every fill-up for the next several months thereafter I would run my car until it was nearly empty and then alternate the fuel, generic, Chevron, generic, Chevron… This experiment went on for several months and the result was always the same, the generic gas always got the better milage! I even took to graphing the results which made for a very nice red and blue visuals that really highlighted the discrepancy. The difference is between 1-2 mpg and remains constant whether it is freeway or surface street driving. In the two years since, I’ve occasionally repeated this experiment and the generic gas always wins out.

When I bought the car, gas was over $5/gal. and the difference in price between the two types of gas was over $.40/gal. so the effect on the wallet was huge. Then the recession hit, the price of gas fell and it didn’t matter, I’d fill-up where it was most convenient. Now gas is going up again and the price difference is about $.20/gal. With a 60 mile daily commute, it adds up fast.

My question is, if Chevron gas does make your car run cleaner and more efficiently, then why isn’t that reflected in improved gas milage?

That’s a first. I was never aware that one gasoline was superior in any way to another. Major differences being from one region to another due to local and not brand. I’ve never seen any independent test results to bear it out either.
They all use the same base gasoline and get their additives from the same suppliers. So IMO, the overall affects are negligible and not consistently measurable. Don’t worry. Use the cheapest gas.

Is it the promoters of Chevron that is linking “cleaner running” (what ever that means) and increased mileage or is it you that is making the link?

GM does promote the use of “Top Tier” fuels (and fuel injection system cleaning in some cases) for various reasons, this may be where you are getting off course.

In the past, I have bought Toyota, Chrysler, and Honda cars. Every time the car dealership has recommended Chevron gas. So it’s not that just a single dealer owns Chevron stock. And it hasn’t just been the suggestion of “top tier” fuels, the recommendation has always specifically been for Chevron because of their additive that the dealers have said made it a cleaner burning fuel.

I would have expected that a cleaner burning fuel would get better gas milage, or if it was nonsense, the mileage would be the same. But it hasn’t been the same. The generic has always been better, not by much, but enough to take me free to work once every two weeks.

Here in Denver Conoco/Phillips is considered the “top tier” brand and recommended by BMW and others. A few years ago, it was Amoco/BP before they pulled out of the Denver market.

Actually, any brand name gas is as good as another. They all come in the same pipeline from refinery to distribution center. Cheveron, Shell, Conoco, etc. put in a few additives and slap their name on the pump.

I’ve not noticed the mileage difference between brands, but have between Colorado “winter gas” (with ethanol) and summer gas.


Cleaner burning has no direct relationship with mpgs. Only if your car’s fuel system had deposits interfering with efficient operation would the gas make a difference, and only after a number of tanks. The difference you found might be caused by a difference in ethanol content. Or it might be caused by slight difference in the calibration of the different gas pumps.

I agree with dagosa (am I allowed to do that?). The basic gasoline is the same. Top Tier gas companies put more additives in to achieve the rating. Still, I have never noticed a difference. It turns out that a Top Tier supplier has about the cheapest gas in town, so I often shop at that Shell station. If not them, it’s a Sunoco station across the street.

You may be right, but my impression is that up 'til World War II, “gasoline” was the stuff that boiled off of crude oil in a certain temperature range. During and after the war demand developed for slow burning (“high octane”) fuels that could be burned in high compression engines (primarily aircraft, later cars). So they started blending “better” gasolines. And for quite a while – decades – brand probably did matter.

Modern gasolines are sort of a witches brew of light hydrocarbons tailored to the demands of motorists, the cars they drive, the EPA, the equipment present at the refinery and the feedstock used as well as probably a zillion other things like the desire to slowly get rid of all that benzene the former purchasing manager bought for no good reason.

I could be wrong, but I doubt that the Chevron gasoline purchased in Denver in February is much like the Chevron gasoline being sold in San Diego in August. (And I think the air pollution folks would be most annoyed if it were).

My belief. No two gasolines are alike, but the consumer has no way to know which is best for his/her car. Buying the cheapest gas one can find with a suitable octane rating is very likely as good a strategy as any.

Anybody actually know different?

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My brother in law delivers gasoline and he hits all of the stations; national names or mom and pop stores. In a nutshell, it all flows out of the same tanker.

I’ve used both for decades and have never found one whit of difference between them; and believe me, I nitpick a car to death.

Just to add to “OK”'s comments which I fully agree with, it seems the only worthwhile recommendation of one brand/station over another would be based in the competence of the delivery system. I’m sure it’s all regulated, but maintenance of equipment, filters and storage would mean the most to me as which one I preferred if prices were the same.
Just trying some way, to milk answer out of this question of preference of one gas over another…

I never understood why the oil companies advertised their gasoline. Gas is gas, and you buy it where it is cheapest, right? I was past the age of 30 before I realized some people really believe one brand is better than another. Obviously I’d never make it in marketing. Same reason I never bought Exxon stock. In my mind, I couldn’t understand how they stayed in business charging 4 cents more than everyone else! Silly me.

One warning: Oftentimes when you see “Top Tier” gasoline at or below off brand prices, when you pull up to the pump, you’ll see a sticker that says something like “Gasoline may contain a blend of up to 15% ethanol”. So you’re getting less BTU’s for your money!

Gasoline is a bulk commodity made to a federal standard. It’s traded like wheat and corn on commodities markets…The oil companies and refiners all have product sharing agreements which allows them to supply each other in different areas of the country…

Oil companies advertise because it works. When you get to the consumer level, in a sense, nothing is a commodity. You are influenced by how you feel about certain brands. There is a perception, based on advertising, that Chevron’s fuel is better than fuel sold at other stations. Chevron’s advertising suggests your engine will be cleaner; specifically, the valves and injectors. That is all. They make no claims about fuel economy. The same can be said for Shell.

Using Chevron is NOT recommended by the manufacturer…it must be a local thing…Don’t know how the manufacturer could recommend it…since here in NE…We don’t have any Chevron gas stations (at least where I travel they don’t).

There was an informative presentation on the History channel that indicated that the pipeline delivery system was a business unto itself, transporting fungible petrol products throughout the US over the same pipelines. Separators allowed different products to travel through the same pipes to the same distributors. Everyone gets the same petrol products.

In my area many of the “generic” gas stations sell gasoline with no ethanol. I always get better mileage using their gas than the major brands, which all have ethanol in them. Even the Top Tier brands have ethanol.

I fill up wherever and whenever it’s convenient. Sometimes it’s a brand name, sometimes Top Tier, and sometimes generic. I notice differences in fuel mileage, but I’ve never had any problems associated with gasoline.

I saw that show. Yup, it’s true. It all goes through the same pipelines.

I decided to make use of the automatic mileage calculator and see if there was a difference in the milage between Chevron and the cheapest gas station in town, figuring that if Chevron really did make your car run cleaner and more efficiently, there should be a corresponding increase in gas milage.

You did a good job of eliminating most all variables. There is still a possibility of luck or some difference in your driving, even if you did not intend any. Overall I would tend to believe you did get a little better mileage. Well done

As noted it is most likely due to the additives, but then aren’t the additives part of the gas you are buying? :slight_smile:

BTW your results do so an increase in efficiency, but they did not measure how clean the engine was.

There is a big problem with this test. Since you were comparing gas based on the cleaner more efficient claims of Chevron as opposed to cheap brand X. By running a tank of Chevron through your car, which theoretically “cleaned” your engine, then running a tank of brand X, all you did was clean an engine for the brand X gas, which would lead it to have a better mpg and then have an unfair advantage for then you would fill the tank again with Chevron which would then have “clean” out the junk from brand X gas which would lower its mpg. Better test would have been to have had 2 identical cars, one running only Chevron and the other brand X and then compared. Since I do tend to run Chevron through my vehicles recently I did noticed an increase in mpg because I switched.

Sorry for the late response to this but So they started blending “better” gasolines. when referring to higher octane. I know the comment is in quotes but many people actually do think that high octane gas is “better” when in reality it is just higher octane. Better gas is fresh gas with appropriate area added additives. We all know what “bad gas” refers to and that has nothing to do with lower octane.
Just a rambling thought