Bad Gas
January 21, 2005 12:06 PM   Subscribe

Is there such a thing as "bad" gasoline and can it mess up your car? (+)

My mother (age 77) says that there is, and that you should be careful to buy gas only from large corporate type places. I mostly buy my gas from the kind of skeevy independent convenience store on my corner, where it is incredibly cheap. My car hasn't been running well in some time (shakes, shudders, coughs) but then, it's a 7 year old Saturn with 135,000 miles on it. Should I switch to Exxon or something? Isn't it true that gas nowadays is much more tested than in the past and much more difficult to mess with? If the gas was bad in some way, than in what way is it bad and how did it get diluted/added to/whatever? My convenient gas seller has incredibly high numbers of cars going through there, it would seem difficult to adulterate the gas every day or something.
posted by mygothlaundry to Travel & Transportation (40 answers total)
Larger companies tend to put more additives and "cleansers" (of dubious effectiveness) into their gas.

Smaller non-franchise places would potentially have an easier time committing fraud (selling 87 octane as 93, for example) though the two cases of this I remember reading about happened at an Exxon and a Texaco station.

The really involved car-wonks (these guys have their old oil analyzed after it's changed) on the Mazda 6 forums I frequent claim that Shell has gas with a relatively high sulfur content, and to avoid it as it can mess up the catalytic converter. This seems a bit extreme - do with that info what you will.

My advice: If you're willing to spend a bit more, try a few tanks from an Exxon or a Getty - if you notice a difference, I'd consider switching. If not - continue enjoying cheap gas.
posted by jalexei at 12:20 PM on January 21, 2005

Supposedly, all gas comes from the same suppliers. Brands can put their own additives in it (Ultra Clean Formula Blah Blah), but basically, it's the same.

What can make an impact from scary gas stations is the quality of their equipment. Old stations can have rust in their tanks, leaks that let a little water in, etc. This can impact the purity of the gas and performance.
posted by Gucky at 12:22 PM on January 21, 2005

meaningless anecdote: my dad, who lives in the burbs, sold a car to a guy who lives in Chicago. A few years later, the guy has to replace his gas filter, which my dad has never had to do on the ~10 cars he has owned. Consequently, my dad thinks that city gas is "messed up."
posted by goethean at 12:33 PM on January 21, 2005

You can also buy anti-knock and engine cleaning fuel additives from an auto supply store. It might be worth giving one of those a try.
posted by mr_roboto at 12:41 PM on January 21, 2005

Meaningless Anecdote II:
I was heading out on a road trip with a friend, and another friend's dad warned us not to stop at any small gas stations, because they don't sell their gas as quickly, so it sits in the gas tank and accumulates water condensation, and will mess up your engine.

Well, the only place we could find to fill up was a dinky independent station that looked decrepit. My friend's car started acting up like crazy after about 5 miles, and died completely in about 30 minutes. He had to get his fuel pump replaced. He became obsessed with bad gas after this.
posted by agropyron at 12:41 PM on January 21, 2005

You can definitely get water in the gas. Happened to my dad once and it was at a local rinky-dink operation. Empirircal evidence does not = a trend, but good luck convincing him after the repairs.
posted by yerfatma at 12:46 PM on January 21, 2005

anecdote #3: For eons my mother paid a premium for Shell gas in her Pontiac. I went to the Clark station instead where gas was regularly .10 cheaper. I never had a lick of trouble with my fuel lines, engine, exhaust... nada. Mom's car? In the shop regularly.

Enjoy the cheap gas, but buy a Honda next time. ;)
posted by FlamingBore at 12:50 PM on January 21, 2005

You can definitely get "bad" gas, although what "bad" means can differ. There was an independent gas station in my small hometown that eventually got shut down for not taking care of their tanks--they were infamous for years before that for selling gas that would mess up your car.

As I understand it, newer regulations and requirements make it a lot harder for stations to sell gas with _sediment_ in it, or at least, if they do it nowadays, they're committing a much worse infraction. Used to be you would get a small fine, but now you could get driven out of business quickly, so it's less of a risk.

I think you can still end up with water in the gas, though, if they're careless. That could definitely make your engine run poorly.

Just try being a little scientific about it--stay off the cheap gas for about a month, and see if the condition improves. If you've still got the problems, then it's probably not the gas (or the damage is permanent).
posted by LairBob at 1:12 PM on January 21, 2005

Absolutely there have been instances of bad "gas" out there, but I really don't know how common it is. Mostly it's small operators adulterating their tanks to bump profits. Sediment in your gas is really bad news, but not so common nowadays (still happens with diesel though).

Using agricultural gas (gasoline sold without tax to farmers, dyed purple or red) is another common dodge. That's not bad for your vehicle, but it's a huge fine if you're caught.

Bad diesel is even more common and a real headache to the trucking industry. "Red" (agricultural) diesel is a problem too.
posted by bonehead at 1:15 PM on January 21, 2005

I always heard Arco cheap gas was worse for your car. How do they sell fuel at 10 cents per gallon cheaper than everyone else? What corners are they cutting?
posted by mathowie at 1:20 PM on January 21, 2005

Your car probably just needs a tuneup. Get new spark plugs, plug wires, a distributor cap and rotor. Change the air filter, fuel filter. It'll probably run fine after that.
posted by knave at 1:21 PM on January 21, 2005

You certainly CAN get a bad tank of gas. Water contamination is probably the most common problem causing 'bad gas.' As for the different brands, I personally don't think they matter a whole lot for day-to-day driving. A friend of mine swears by BP, but I really can't tell the difference between BP and Exxon, or any other brand I've tried.

As for the original poster, your problems could be caused by a number of things, and gas is about the last one I would expect. Have you had regular service done on your vehicle? When is the last time your coil pack, plug wires, and spark plugs have been replaced? If the answer is never, they are ALL overdue for replacement.

Only an inspection by a competent (and honest) mechanic can tell for sure, but with the age of the vehicle I would suspect a dead miss (i.e., ignition trouble) or fuel-system related trouble (your injectors may need to be cleaned, the fuel pump may be defective, your fuel pressure regulator may be defective, your fuel filter may be clogged, you could have a vacuum leak, etc - you get the idea.)

Get it checked out. Some of the above problems can develop into very serious and expensive problems if left untreated. The fuel-related problems in particular can lead to internal motor damage.

High octane gas is NOT something your Saturn needs - or can deal with. Please don't put higher than 89 octane in. Don't add octane booster either. Your motor does not have a high enough compression ratio to need high-octane fuel (that's all high octane fuel buys you - the ability to compress it more without it spontaneously igniting - "knock".)

Putting high octane fuel in a motor with a lower CR is bad because it burns too slowly when under-compressed. It is not 'high performance gas',' it is gas used in high-performance motors.
posted by metamarcusb at 1:27 PM on January 21, 2005

Supposedly, all gas comes from the same suppliers. Brands can put their own additives in it (Ultra Clean Formula Blah Blah), but basically, it's the same. This is not 'supposedly' this is a fact. (I used to be the ass.-man. at a big-chain gas station). The additives do make _some_ difference, but you can buy these sorts of additives in a bottle and add them to any gas.

What can make an impact from scary gas stations is the quality of their equipment. Old stations can have rust in their tanks, leaks that let a little water in, etc. This can impact the purity of the gas and performance. Right. This has more to do with the age of the functioning parts of the station than what the label on the sign says. But you can't tell the age of the tanks by looking at the above-ground station. It's pretty easy to give the store a facelift without touching the actual mechanics that put gas in your car. The station I worked at shut down for 4 months to do a complete overhaul of the store and completely replaced the tanks, pumps, etc at a cost of 1.5 million dollars. How many independents do you think have that kind of money?

Any company can potentially have a problem with their gas. In May 2004, for instance, Shell & Texaco stations in Florida had a problem with sulphur in their gas that damaged some people's cars, and lawsuits ensued.

From years working in a chain, I'm in the habit of buying my gas there, and I continue to. My mom puts the cheaper (and closer to her home) gas into her Honda and has no problems.

Should you switch? I wouldn't bother. If I was going the cheaper gas route regularly though, I'd occasionally dump in a bottle of engine cleaning agents, as extra insurance. That's just me.
posted by raedyn at 1:30 PM on January 21, 2005

I always heard Arco cheap gas was worse for your car. How do they sell fuel at 10 cents per gallon cheaper than everyone else?

They make it up in volume, I guess. One thing that helps: they don't take credit cards, and they make customers pay the processing fee if they pay with a debit card, which is easily 2-3 cents per gallon of the difference right there.
posted by kindall at 1:30 PM on January 21, 2005

It's possible that a given gas station might have bad tanks, or adulterate, or whatever, but I can't think of any reason why an Exxon or Shell would be any less likely to do that than Bob's House O' Gas. Big-corporate gas might have more scrubby stuff in it, but who's to say whether it does any good or not.

In the bigger picture though, it's all the same. There's a big network of pipelines that ship gas all over, and the gas you put in at one end is not the gas you take out at the other. Shell doesn't sell you gas that Shell refined, Exxon doesn't sell you gas that Exxon refined (except by random chance). 89 octane gas is 89 octane gas, out of the pipeline.
posted by ROU_Xenophobe at 1:33 PM on January 21, 2005

I used to drive a 1968 VW Karman Ghia. Year round but more so in the winter it would grumble and kick when trying to accelerate. I talked to my mechanic about it and he told me to stop going to Texaco and start going to Chevron. He said that (at least here in Portland Oregon due to state laws...) in the winter most gas companies put added oxygen (...i think...) in the gas to somehow lower the smog. He said that Chevron was the only company he knew of that didn't do it during the winter and that the cold weather, added to the oxygenated gas would cause my problems. I sold the car soon thereafter but after switching to Chevron the car did seem to run a little better. I wish I would have kept the car longer to test it more but I had to sell it.
posted by pwb503 at 1:37 PM on January 21, 2005

here's a big network of pipelines that ship gas all over

Umm, isn't that natural gas? Around here we've got a bunch of refineries on the Schuylkill river and they take delivery of oil by barge, refine it, and then deliver gasoline by tanker truck.
posted by fixedgear at 1:38 PM on January 21, 2005

A mechanic told this to me, so take it with a grain of salt, but this is what he told me. The gas at the refineries is stored in big cylindrical holding tanks. As the gas sits in there, waiting to be distributed, particles in the gas start to settle towards the bottom. The gas at the top cost more, and is bought by larger chains (chevron/texaco). The 'bottom of the barrel' stuff is bought up by the cheaper places like Arco and the local cheap gas stations. So the contaminants in the cheap gas can cause you problems when pumped into your engine for years but cost you less when filling up your car.

Again, this is just what one mechanic told me. Make of it what you will. And if I am way off base on this, some one please let me know.

And along with what pwb503 said, Chevron is the best place I have found for gas in the winter. Driving a 74 Thing with that oxygenated gas is horrible. Chevron has my business year round for that fact alone.
posted by chrisroberts at 1:54 PM on January 21, 2005

At least in my home town there are some full service gasoline stations that compete on price with the large no service stations. They do it buy buying the bottom of the tankers. As a result there tends to be more water or other contaminents in it.
posted by substrate at 1:58 PM on January 21, 2005

I noticed that an old car of mine ran substantially better on ethanol-free gas. At the time (where I lived) Chevron and Amoco were ethanol-free, but Sunoco, BP, and Shell all contained 10% ethanol. In many states, the retailer is required to label the ethanol content of the fuel at the pump.
posted by trharlan at 2:08 PM on January 21, 2005

long ago i worked as a gas-pump jockey at a station with sedimented tanks; we knew it was there because the muddy gunk stuck to the stick we used to measure the amount of fuel in underground storage. no one who worked at the station filled their personal cars for, like, an hour after the tanker truck refilled us. the mechanics said the gunk, stirred by filling, would kill injectors, maybe the whole fuel system; that's bad gas.

eventually, i'm fairly sure, this build-up of gunk compromised the tanks; a few years later the station made headlines when these same tanks were found to be leaking; apparently gas can leach a loooong way, ruining the groundwater; once again: that's bad gas.
posted by RockyChrysler at 2:14 PM on January 21, 2005

I always get my gas on the Reservation a mile from where I live. I do know people who say "oh... rez gas will mess up your car," but I've never seen it.
My last car died (read: husband had an mishap with a Buick) at almost three hundred thousand miles (I think it was something like 289,950 or so), and I had used almost nothing but rez gas for the last four years I'd had it without any issues.
posted by Kellydamnit at 2:16 PM on January 21, 2005

here's a big network of pipelines that ship gas all over

Umm, isn't that natural gas?

no. gasoline, too, is transported via underground pipelines over long distances. these pipelines occasionally fail.
posted by RockyChrysler at 2:21 PM on January 21, 2005

In the Okanagan Valley (BC), our gas is supplied from Alberta. The same pipeline is used both for crude oil deliveries to Vancouver, and gasoline deliveries to Kamloops, from which the Interior is serviced. In between types of product they run a "pig" through the line.

The "pig" is supposed to clean the line and separate the product.

It doesn't.

Consequently, I have to replace my fuel filter every year or two, and the fuel pump every five to ten years. When I replace the filter it pours out a cupful of the nastiest black, gritty sludge you could ever imagine.

Cars in the Okanagan are reknown for their fuel system problems. The quality borders on criminal, particularly considering the premium prices we're paying compared to Vancouver.
posted by five fresh fish at 2:23 PM on January 21, 2005

I should mention that I filled up exclusively from Chevron for nearly a decade, during which these problems occured; and then from Petro-Canada, with the same results.

I am now filling up at a discount gas place, believing that it simply can't be an order of magnitude worse.
posted by five fresh fish at 2:26 PM on January 21, 2005

Since you're driving a Saturn, I'll pass this along too. My friend's brand new Saturn had to be returned for serious engine work after the first new tank of gas. She had used Texaco's gas and their additives had a corrosive effect on the seals, valves, or something to that effect. All of this was 6-7 years ago. Since she had it repaired and not used Texaco (which is now BP around here) she hasn't had a problem.
posted by ..ooOOoo....ooOOoo.. at 2:37 PM on January 21, 2005

What others have said about contaminents. One other thing that used to be a problem but less now because of fewer stations is old gas. Gas starts varnishing up almost immediately. Stations that don't do alot of business will have poorer quality gas just be they get a load than just after.

Personal observation: there is a discount gas place that I buy propane for my Powerwagon but I stopped buying gas for my Dakota at because I documented a 0.5l/100km drop in gas mileage when using their gas.

You can get bad propane too (iIt'll have too much natural gas and butane in it)
posted by Mitheral at 2:56 PM on January 21, 2005

Since you're driving a Saturn...

I doubt that was anything brand-specific. I had the same with a late-80s 300ZX, and it was a car-design issue.

They built the car with gaskets'n'such that would get eaten away by the newer oxygenated gasolines in winter, was all. End result: free repairs, and new seals and gaskets and whatnot that don't get eaten up by new gas.

I rather doubt that you'll find one brand that's oxygenated and another that isn't in a given area. Oxygenation is, IIRC, an EPA regulation, not an option that the gas stations have.
posted by ROU_Xenophobe at 3:05 PM on January 21, 2005

In regards to the contaminants like sediment, why doesn't the fuel filter take care of that? If you're using gas with lots of sediment, wouldn't you just need to change that filter more often?
posted by spaghetti at 5:20 PM on January 21, 2005

Regarding high octane gas: Any possible problems that could arise from an accidental tank of it? (I wasn't paining enough attention when selecting the grade until almost done.) 2000 Saturn, if it matters.
posted by MikeKD at 5:39 PM on January 21, 2005

"One other thing that used to be a problem but less now because of fewer stations is old gas. Gas starts varnishing up almost immediately. Stations that don't do alot of business will have poorer quality gas just be they get a load than just after."

There was a station near an engine shop at which I worked, and the owner of the engine shop insisted on filling all the company vehicles there, even though the gas was horrid-smelling and made for terrible performance, because it was five cents a gallon cheaper. Whenever I'd run an errand in my personal car, I'd insist on a gas voucher instead of the company card - there was no way I was running that paint thinner through my engine.
posted by mr_crash_davis at 5:47 PM on January 21, 2005

And MikeKD, you're not going to hurt anything other than your wallet by over-grading your gasoline.
posted by mr_crash_davis at 5:47 PM on January 21, 2005

I have a somewhat meaningful anecdote. My husband used to drive gas tankers. He has many fine qualities but "attention to detail" is low on the list. This often leads to exciting learning opportunities.

For example: You are hauling 20 tons of ethylene glycol (antifreeze) and you park your truck on a hill while unloading. Your gauges are broken. The loading hose stops flowing and you assume the truck is empty, but in fact it still has a thousand gallons or so in the downhill compartment.

Your next load is 20 tons of gasoline. You attach the hoses to the truck and start loading gas. Oddly enough, that downhill compartment is about a thousand gallons short when you fill it. You disregard this because you're running late.

The next gas station gets a thousand gallons of antifreeze mixed in with the 92 octane, and a bunch of strangers wonder why their cars run funny for awhile. But hey... another day, another dollar.

Let's not even get started on what percentage of gas tanker drivers (who are known as "suicide jockeys" to other truckers, which may tell you something about their general outlook) even bother to put the correct octane in the correct tank. If the station's tank is marked correctly. Which it sometimes isn't.

Bottom line: It's mostly just the luck of the draw. But in general, small rural stations are way more likely to have contaminated gas, just because their turnover is so much lower than urban/highway stations.

And if you notice that your gas is pumping extremely slowly at any station, stop! Hie thee elsewhere or see if a higher octane pumps faster. Slow pumping is your signal that the underground storage tank is almost empty and you're sucking up sludge. Yum!
posted by naomi at 6:15 PM on January 21, 2005

This has been fascinatingly educational - thanks all!
posted by jalexei at 6:51 PM on January 21, 2005

yeah thanks for the read folks. $0.02filter: Chevron all the way. BP if you can't find one. After that, major gas stations, then Big Jim Bob's white lightnin', then discount gas stations. Good luck.
posted by petebest at 7:24 PM on January 21, 2005

Another Anecdote:
An ex-girlfriend would fill up her brand new Corolla at Canadian Tire because it was cheaper gas for the same octane. I can't recall what sort of trouble she had, but Toyota asked her what kind of gas she used once they looked into the problem. She told them. They said to stop, it was damaging to the engine. Something about deposits...

Collusion and corporate conspiracy posts may follow. I apologize.
posted by juiceCake at 7:40 PM on January 21, 2005

I was a party in a class action suit against a gasoline distributor whose gas was really unlabelled gasohol (gasoline + ethanol). This was about 20 years ago. I went through three fuel pumps before I figured out that it was the gas I was using burning out the diaphragm of my fuel pump(s). This problem was reported in the paper and I contacted the attorneys handling the class action suit. I had receipts both for gasoline purchases and for replacement fuel pumps (which I had installed myself). It came to about $300. My portion of the settlement? $10.
posted by TimeFactor at 8:00 PM on January 21, 2005

In areas with a cold winter, gas is formulated differently in winter than summer. If you have summer gas left in your car it will start much harder if it's cold out (0 deg F or less). I've run into this trying to start one of my tractors in winter when I've still got gas in it from my tank that was filled in the summer.
posted by rfs at 8:55 PM on January 21, 2005

rfs is referring to oxygenated gasoline, which is supposed to reduce CO emissions in winter.
posted by mr_crash_davis at 9:03 PM on January 21, 2005

Wow, thanks y'all! This is extremely helpful and I think I'm going to stop buying gas at my corner gas-o-mart (their motto: weird enough to be worthy of their own short independent film) for a while and see what happens. I went into this thinking my mother was crazy but I am rethinking that premise - dag, yet again. I did just have the car tuned up recently and it didn't do much good, so maybe it is the gas. I have absolutely no problem believing that the local's tanks are rusty and/or leaking and/or whatever else bad may happen, hell, they could have unsuccessful crack dealers in there, so I'll try expensive gas (don't think we have Chevron in western NC) for a while and see what good that does. Thanks again!!
posted by mygothlaundry at 10:01 PM on January 21, 2005

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