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Old 04-09-2002, 01:29 PM   #1
sajohnson
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Default Anyone notice a difference in mileage/performance with different brands of gas?

All my life I've heard people claim, "My car will only run right on 'X' gas" or "I get terrible mileage when I fill up with 'Y' fuel".

Personally, after driving maybe 750,000 miles in many different cars, trucks, and vans, I have yet to notice a difference.

My commute is the same every day and I keep track of mileage and also periodically check performance by running between two points (same start speed, note final speed). I have never found ANY difference. In fact, both my WRX and my previous vehicle (a NX2000) are so consistent it's spooky. The fuel light even comes on at the same mileage, usually +/- one mile!

What's your experience?
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Old 04-10-2002, 08:41 AM   #2
99OBSter
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I fill up with whatever gas station is closest. The only time I noticed a difference was when I was in Colorado and used the 89 meth/gas mix. At altitude, I notice worse gas mileage.

At sea level (in Ohio), I don't notice any mileage difference.

But, I will say that if I keep the car under 3K rpm on highway cruising, I get MUCH better mileage. Maybe as much as 50 miles per tank.
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Old 04-10-2002, 06:34 PM   #3
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I always fill up with Sunoco 94. If my fuel light comes on I'll stop and put $3 in of whatever is near and then fill at the nearest Sunoco.

99OBSter, I agree...if I keep my rpm's under 3500 through all the gears (5 speed) I'll get much better mileage. My best yet is 322 miles out of a tank (14 gallons) and that's a clean 50/50 split of highway and city driving.

My usual style of driving yeilds roughly 270 miles per tank. I really do believe that the car runs better on 94...but who knows.

leeberbs
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Old 04-11-2002, 03:18 AM   #4
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Quote:
Originally posted by leeberbs
I always fill up with Sunoco 94. If my fuel light comes on I'll stop and put $3 in of whatever is near and then fill at the nearest Sunoco.

99OBSter, I agree...if I keep my rpm's under 3500 through all the gears (5 speed) I'll get much better mileage. My best yet is 322 miles out of a tank (14 gallons) and that's a clean 50/50 split of highway and city driving.

My usual style of driving yeilds roughly 270 miles per tank. I really do believe that the car runs better on 94...but who knows.

leeberbs
Test it! My guess is it's 'placebo effect'. As posted above, my experience and everything I've read leads me to believe that using higher octane than the mfr. recommends is a waste of money.
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Old 04-11-2002, 03:35 AM   #5
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Default I agree...

I think higher octane is a waste of money. I have a 98 gt wagon with nothing other than a K&N (so far) and I can get 300/tank of 13-14gal consistently. Put in regular unleaded, usually Texaco. I don't know if it is any better than any other name brand, but I definitely avoid filling up at some of the super cheap gas stations because I do notice a difference, but among the big names, no difference here. Oh yeah, and the under 3000 rpm doesn't usually happen for me. You know, the 21 year-old syndrome.
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Old 04-11-2002, 04:27 AM   #6
sajohnson
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Default gtwagon941

When you say you notice a difference between name-brand and 'generic' gas, what is it that you notice? Is there a difference in mileage or performance?

I've used all the major brands and the no-name ones and I've never noticed a difference.

I've even asked the tanker drivers, and they say the gas is the same-it's the additives that might vary. The Feds regulate the minimum amount of various additives though, so I'm not convinced there is a huge difference.
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Old 04-11-2002, 01:29 PM   #7
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Default both

I notice a decrease in mileage and just an overall decrease in engine "happiness." By that I mean ability or whatever to giddy up when I say so. I know that there are standards, but those additives are exactly what changes things. Arco gas around here falls under the category with additives that are really negatives. Whether it is more alcohol or whatever, this gas flies through my car and although it is usually .05 cheaper/gal it isn't cheaper when I have to fill up more often. Seems as though there probably is some "official" research on this topic to be found on the net. What exactly is added to which gases and what the side effects are? Maybe it is just me or my car, but I used to have an 87 GL Turbo wagon and it didn't like the gas from generic places even more than my current car.

Jared
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Old 04-11-2002, 11:08 PM   #8
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OK...I'm testing with my current tank. Filled up with Shell 89 today...A departure from my normal Sunoco 94. I will drive my regular style...I'll try, really...which usually gets me 270/tank +/- 5 miles

I just installed a Kartboy short throw and bushings today...wow what a difference. Highly recommend them. Easy install and short, crisp shifts. So that might tempt me to push a little.

I'll post my data in about 250 miles...or...say 3 days.

leeberbs
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Old 04-12-2002, 08:00 PM   #9
stikboy
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Default good question

sorry that i can't answer this question better, but the guys at subaru said that it takes three full tanks or gas for your car to adjust completely to a different type of gas. this means that you shouldn't notice a difference between "good" gas and "generic" gas based on one tank alone. for all you guys trying the gas performance/mileage theory, you will need to test based on your stats before your last fill up and after three full tanks (NO Cheatin'!)

the guys at subaru also said that unless you have your subie all modified or it is a wrx, you really only need to put premium in once a year. otherwise, just put whatever you want in your tank and go nuts.

hope this helps somewhat.

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Old 04-14-2002, 11:23 PM   #10
leeberbs
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I've just returned from a weekend trip to Boston. About 40 minutes into my drive I had to fill up. Mobil was the closest gas so I filled up with 14 gallons of 89.

I left my car in a garage all weekend...didn't touch it till driving back today and I was able to squeeze 403 miles from one tank.

For those interested I averaged between 85-90 mph in the 3500-3750 rpm range.

Next time I make the drive I'll fill up with Sunoco 94 (my regular choice)and see what happens.

leeberbs
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Old 04-17-2002, 06:27 PM   #11
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In brands I can really tell no difference except between brand name and generic (ARCO included). I prefer 76 Mobil and Cheveron over the rest. Maybe placebo or stations my area, but I like them more.

I can definately tell a difference withhigher octane gas. The highest octane in CA is 91. Every now and then I get 3-4 gallons of 100 octane fuel with a tank of gas, so I have about ~93 octane total. There is a noticable difference with in 2 blocks of driving, especially with winter gas. The main thing I notice is the tremor of my car is dramatically reduced, and there is less vibration in the stick shift. It is also seems slightly faster accelerating. To quote my girlfriend: "Yah there is a difference, the car shakes less."

Cost too much to do on a regular basis, but every now and then when out for some spirited driving. Thank you Federal Government for making California adhere to pork barrel laws. And :monkey: to the bastards who are going to make us use ethanol (sp?) at a cost of 10 cents per gallon when we already exceed the air quality standards.
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Old 04-27-2002, 08:45 PM   #12
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I use whatever's cheaper, but I stay the hell away from those no name places. In my MR2, I used Amaco because their premium 93 was a nickle cheaper than Mobil. (Old engine/knocks with anything less) In the scuby, I go to Mobil. It's almost a nickle cheaper than Amaco for regular 89.
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Old 04-29-2002, 02:30 PM   #13
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Default Re: both

Quote:
Originally posted by gtwagon941
Arco gas around here falls under the category with additives that are really negatives.
Arco gas is perhaps the worst thing you could put in your tank. Hmm, my wife's sister had her 2001 civc towed into Honda dealer cuz it died on the road one day. A couple days later when she arrived to pickup her car, the service manager asked her what gas she used. She said Arco. He said never to put that "crap" in her car again. LOL. Turns out the Arco gas was so dirty it clogged all the injectors after years of usage.

Personally, I use 76 and sometimes mobil, or whoever is cheaper. The 76 station just happens to be right on my way home so I guess convience is important too.
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Old 04-29-2002, 02:41 PM   #14
sajohnson
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Default Arco

Quote:
Originally posted by thesmokingman


Arco gas is perhaps the worst thing you could put in your tank. Hmm, my wife's sister had her 2001 civc towed into Honda dealer cuz it died on the road one day. A couple days later when she arrived to pickup her car, the service manager asked her what gas she used. She said Arco. He said never to put that "crap" in her car again. LOL. Turns out the Arco gas was so dirty it clogged all the injectors after years of usage.

Personally, I use 76 and sometimes mobil, or whoever is cheaper. The 76 station just happens to be right on my way home so I guess convience is important too.
I would think the fuel filter would stop 'dirty' gas from clogging the injectors. Without more info, I would think it was just a coincidence that the last tank of gas was from Arco. Or if the fuel was dirty, maybe it was a problem at that particular station. I mean if cars were dying all over America from Arco fuel, they'd be out of business pretty quickly!

Also, I may have misunderstood your post but, a 2001 Civic with "years of usage"? Just wondering.
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Old 04-29-2002, 06:20 PM   #15
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Most ppl vary their type of gas consumption. Its impossible to use only one brand in most cases I would dare to assume.

In my wife's sister's rare case, she's a cheap skate and treated her, yes 1 yr old car (typo from earlier) to nothing but the worst gas since she bought it, Arco. The car died, dealer said clogged injectors and to never put Arco in again. You figure it out. Fuel filters don't catch everything. On another note, Arco has started a major ad campaign to let everyone know that they're gas is the best there is! Funny, guess cliche's are true, sometimes.
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Old 05-05-2002, 12:42 PM   #16
AC Lerok
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a friend of mine from high school's mom is a chemical engineer. she worked for Exxon/Mobil Quality Control and for her job she had this van with a "fake" tank and she'd fill up at a station and take the tank back to the lab to test it for purity, correct octane content, etc. several stations around me that WERE Mobil are now generic/USGas/etc. because Mobil pulled the franchise since the stations weren't up to snuff (bad tanks, pulling octane level bait/switch, not even selling real Mobil gas!).

since i know Exxon/Mobil is taking this action, i feel most comfortable with their product. i've never used Shell in my car, but my mom's car absolutely will not run with Shell gas in the tank.

Sunoco 94 actually gives me worse milage.
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Old 05-05-2002, 06:55 PM   #17
sajohnson
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Default AC Lerock

When you say, "My mom's car absolutely will not run with Shell gas", what do you mean? It won't even start, or it runs rough, loss of power...

Is this repeatable? I mean did she get a bad tankfull at a Shell station and never go there again, or has she learned from experience that whenever she fills up at any Shell station her car runs poorly?

What kind of car is it?

Thanks.
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Old 05-05-2002, 07:14 PM   #18
sajohnson
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Default AC Lerock

I don't doubt that some station owners are guilty of the things you describe. In fact, I seem to remember a news story a few years ago about stations in the Ghicago area selling 87 octane as premium. If I remember correctly it was a fairly high percentage of stations that were guilty of this--like 15 or 20%.

That said, I know some owners get fed up with the rules and restrictions that are put on them by the big multinational oil corporations and switch to an independent for that reason. They claim the gasoline comes from the same refinery (the tanker drivers I've spoken with back this up), and although the additives may vary they all must meet federal standards. Also, they've told me that if they are with a big oil co., they MUST buy from them--however, although the tanker might say Exxon (or whatever) the fuel might be from another supplier! Several owners/managers have told me this. It seems to be one of their dirty litttle secrets. You could be a loyal Texaco customer but sometimes get Amoco gas for example.

Finally, I also remember that years ago BMW did a serious gasoline test where they ran several of their motors the equivalent of 100k miles on various fuels and then tore them down and inspected them for deposits. They actually weighed valves before and after. My memory isn't great but I believe most of the fuels passed the BMW 100k test--even the 'generic' brands.

Food for thought.
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Old 05-06-2002, 01:40 PM   #19
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Default More to think about

I've always tried to stick to major brands (Mobil, Shell and Amoco in my area), as I've had the best 'luck' with them. I've never noticed a difference with new engines, but in the few engines I've had over 100K miles, I definitely noticed that they idled and ran better (more pickup, better mileage) on one of the aforementioned brands than some of the less major brands I tried (Speedway, Marathon or Clark). I also like to stick to the brands above because they are consistently non-ethanol. I believe ethanol does bad things to current cars.

As far as all gas being the same... Here's something I heard, I can't claim to back this up, but supposedly some stations (noteably the "discount" stations) will purchase old fuel. That being fuel which is out of season. So for instance in May, you might still be getting Winter formulated fuel.

As far as noticing differences, its probably hard without running for 6-10 tanks or more, one or two tanks isn't going to do it. Additionally I know that most modern ECMs will adjust to the poorest grade of fuel they encounter (detecting grade through knock detection), and will 'learn' their settings based on that type of fuel. It can take several tanks of fuel to reset those settings (if that will reset them at all). This can be an issue when you run an engine that calls for premium on regular, or if you're coming from altitude down to the lowlands or vice-versa (where octane levels will vary). It can I believe also make a difference if you're say, getting Winter fuel in the Summer, or Summer fuel in Winter.
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