Do You Avoid Buying Gas When...

[Pat Germain]

There are so many "it depends" variables in this subject it's not even funny.
If you deal with one or more engines, of any kind, you'll probably encounter a fuel issue at one point or another in your lifetime. Places that sell "bad" fuel, don't stay open long if at all.
Some vehicles do run better on certain formulations of gas (different stations) but that's about it.
The millions of gallons of gas/diesel pumped each year and the hand full of issues cited, would suggest it's not a widespread problem, or at least not in the last 25 years.
Too many old wives tales and superstitions for me.

^^ Yup.

- All the gas stations in a given area get their fuel from the same distribution point. The only variable is the additives package and water is not among those additives.

- Any modern gasoline engine is designed to burn ethanol-blended gasoline. Running 100% gasoline won't hurt it, but it's not necessary.

- Alcohol is hydroscopic and tends to absorb more moisture from the air that pure gasoline. But as long as the fuel isn't sitting for months on end, it won't be a problem.

- Even 100% gasoline will start to go bad after a few months. Additives like Sta-Bil help, but not indefinitely.

- Seems almost every time I get gas, there's a fuel truck parked at the gas station. Never, not once, have I had a problem with getting gas while a fuel truck was filling tanks.

- The only way there is going to be a lot of water in the gasoline is if:

A: The tank is so leaky that ground water is getting in
B: The owner is putting a garden hose into the tank to stretch the gas

- I have a 1970 Mustang Mach 1 with the factory, carbureted engine. It requires premium gasoline because the engine has high compression (10.7:1). There is exactly one pump in my area that dispenses 100% premium gasoline. It's on the other side of town, it's unattended and it requires a commercial account to use. Not gonna go there. I've been running ethanol blended, premium gasoline in my Mustang for years with zero issues. I have replaced all the rubber fuel lines with modern, fuel injection hoses. Those are resistant to alcohol. No other mods are necessary.

- There is absolutely, positively no reason to run premium gasoline in a small engine unless you have modified said engine to have high compression; which is extremely unlikely. High compression, either from the combination of piston and combustion chamber or from supercharging or turbocharging, is the ONLY reason to use premium, high octane gasoline. Premium/high octane gasoline does not have any more energy than lower octane gasoline. It does not have a better additives package other than the additive which boosts the octane to make it less volatile. Putting premium/high octane gasoline into an engine which does not have high compression won't hurt anything other than your wallet. But it is a complete waste of money.

[Bill George]

I will try to explain for you google mechanics, gasoline from the time is refined starts loosing its freshness and octane. After about 5 or 6 months its starting to go stale and loses some of its octane. Premium gas holds its octane longer and stays fresh longer, for long term storage I use Sta-bil . I have been doing this longer than before the Internet was invented and I do not have issues, period. For me an extra 20 cents is no big deal. A farmer friend of mine goes in town once a year and fills all his tanks for the farm with Premium non ethanol gas, he learned this years ago.

Yes different brands and grades of gas have different additives and its dumped in at the pipeline terminal in the tanker truck, and I have seen it done.

[Edward Weber]

^^ Yup.

- All the gas stations in a given area get their fuel from the same distribution point. The only variable is the additives package and water is not among those additives.

- Any modern gasoline engine is designed to burn ethanol-blended gasoline. Running 100% gasoline won't hurt it, but it's not necessary.

- Alcohol is hydroscopic and tends to absorb more moisture from the air that pure gasoline. But as long as the fuel isn't sitting for months on end, it won't be a problem.

- Even 100% gasoline will start to go bad after a few months. Additives like Sta-Bil help, but not indefinitely.

- Seems almost every time I get gas, there's a fuel truck parked at the gas station. Never, not once, have I had a problem with getting gas while a fuel truck was filling tanks.

- The only way there is going to be a lot of water in the gasoline is if:

A: The tank is so leaky that ground water is getting in
B: The owner is putting a garden hose into the tank to stretch the gas

- I have a 1970 Mustang Mach 1 with the factory, carbureted engine. It requires premium gasoline because the engine has high compression (10.7:1). There is exactly one pump in my area that dispenses 100% premium gasoline. It's on the other side of town, it's unattended and it requires a commercial account to use. Not gonna go there. I've been running ethanol blended, premium gasoline in my Mustang for years with zero issues. I have replaced all the rubber fuel lines with modern, fuel injection hoses. Those are resistant to alcohol. No other mods are necessary.

- There is absolutely, positively no reason to run premium gasoline in a small engine unless you have modified said engine to have high compression; which is extremely unlikely. High compression, either from the combination of piston and combustion chamber or from supercharging or turbocharging, is the ONLY reason to use premium, high octane gasoline. Premium/high octane gasoline does not have any more energy than lower octane gasoline. It does not have a better additives package other than the additive which boosts the octane to make it less volatile. Putting premium/high octane gasoline into an engine which does not have high compression won't hurt anything other than your wallet. But it is a complete waste of money.

I agree but for one some item.
As someone who has built and rebuilt many, many engines, premium leaves a cleaner engine inside, IME.
Premium (whatever that is these days, 91, 93 ?) may cost more and do little for most engines, as you say, but a compression ratio in the high 10's or 11:1 is not that uncommon these days and some cars you might not expect can benefit.

[Pat Germain]

I will try to explain for you google mechanics, gasoline from the time is refined starts loosing its freshness and octane. After about 5 or 6 months its starting to go stale and loses some of its octane. Premium gas holds its octane longer and stays fresh longer, for long term storage I use Sta-bil . I have been doing this longer than before the Internet was invented and I do not have issues, period. For me an extra 20 cents is no big deal. A farmer friend of mine goes in town once a year and fills all his tanks for the farm with Premium non ethanol gas, he learned this years ago.

Yes different brands and grades of gas have different additives and its dumped in at the pipeline terminal in the tanker truck, and I have seen it done.

While I've never worked at a service center, I have been working on cars and trucks since the late 1970s. I have rebuilt many engines. I have restored multiple classic cars. I don't think that makes me a "Google Mechanic". But OK, sure, FIVE OR SIX MONTHS can affect octane. Your typical daily driver does not let gasoline sit in a tank at home for five or six months.

[Tom M King]

Octane is just the ability to resist pre-ignition-necessary only for some combination of high compression and high rpm's. Tolulene was at one time the primary octane additive. It might still be. I don't claim to know.

Gasoline doesn't have more "power" in it because it has more octane. At one time, they were running over 80% tolulene in Formula 1 cars and they came out with a rule that fuel used had to have a max of 80% Tolulene.

Fortunately, there is no trouble buying non-ethanol gas around the lake here. Ethanol gas has kept mechanics in business for years from boats and jet skiis hanging in boathouses over a Winter with ethanol gas in them all around the 350 miles of shoreline here. I think most have learned now.

[Bill George]

You folks need to re-read what I wrote... its for small engines chainsaws, farm equipment and the like where can sit for months. If an engine calls for high octane premium gas that is what you need to use. Can't see spending that extra money, sell the car!! You can buy additives to boast the octane and I have heard it helps.

I helped my dad on that small farm overhaul a Avery tractor 4 cylinder engine before I was 12 back in the 50s sometime. A engine with premium gas will start better and faster than regular gas that is old and stale.

[Edward Weber]

If you're going to let something "sit" for long periods of time, take precautions.
Where I live, none of my equipment sits idle very long at all. I do agree with Bill that Premium does not seem to go off as fast as lower octane fuel, IME This makes ift better for storing "extra" gas for emergencies.
I don't have fuel related issues or horror stories, so I'll continue with my methods until I do, then I'll determine why.
(Disclaimer, not a google mechanic)

[Maurice Mcmurry]

My father in law has a McCullough chainsaw from the 1970s. He always ran it dry and shook every drop of gas out of the tank before putting it away for the season. He last put it away in 2016. I put fresh gas in it last summer and it started right up. I put it away dry too. It will have to have new fuel lines this spring. I am sure it will start right up.

[Tom M King]

Bill, I wasn't trying to argue with you. I was just trying to add something to the conversation that a lot of people don't know.

I never felt comfortable running all the gas out of any 2-stroke. I use the gas on/off valve for the kill switch on four stroke things like a generator or pressure washer that might not get used for years.

I don't let gas sit in anything for long though. That generator and pressure washer get the gas line taken loose and the gas drained out of the tanks. They both always start years later.

For 2-strokes, I always worried about the last few revolutions being unlubed when running one dry. I do pour the gas out of any that are going to sit, and with the switch off and choke on, I pull the cord a few times. I don't care that the cylinder is flooded, but hope that the needle valve is left open. My 066 can sit for years and always starts after a few pulls when treated like that. I have way too many different small pieces of equipment to start every month, or even every year, so it all sits until it's needed.

I don't have any problem with it running non-ethanol for as long as it needs to sit, but I had to replace five carburetors one year when an unscrupulous person bought a local gas station and sold ethanol gas out of non-ethanol pumps. He ended up going to jail for other fraud in a boat business selling motors and leaving the crates looking like the motors were still in inventory.

I burn way too much gas around here in small equipment to ever worry about any going stale. The big mower probably burns at least ten gallons a week during grass growing season, but I still don't feel comfortable running ethanol gas in it. That 35hp Kawasaki is a great running motor, and it gets a lot of work done in an hour, but it loves gas. 187 hours on it now in three years, but it's cut a Lot of grass. I've changed oil in it four times and just changed the air filters this morning. I can't remember the last piece of small equipment I wore out, not including regular riding mowers.

[Bill Dufour]

When the price is going down I buy at Arco that gets two or three deliveries a day. If the price is heading up I buy at a local independent that only gets a delivery once a week or so. Never sure if I should buy a full tank or just enough to get by until the price drops more. With an electric lawnmower, chainsaw etc. I no longer worry about filling gas cans at the lowest price for the season.
I still buy a lot of stamps right before the price goes up.
Bill D

[Warren Lake]

there are a number of you tubes that say there is no benefit to premium in lower compression motors. There is one ive seen past that took the motor apart and proved there was on the Shell V power I believe do to additives and it was cleaner. I just dont remember which one it was and thats why I listen to one friend that runs it in his chainsaw and other stuff for clean aspect. I have one motor that is 11:1 and will have to talk to a pro before its decided how that will be rebuilt. when I was first buying gas for that Sunoco Gold had lead and was 103 octane and it was pink that was in the 70's

[Bill Howatt]

The biggest problem with deposits and fouled plugs was from the lead in the gas and carburetors being poor at ideal fuel mixtures especially for rare highway driving. Back in my youth, drag-racing friends used to buy high premium gas across the border in the US because a certain station on the way to the strip had higher octane gas. Idea was to be able to fudge the timing a bit more without pre-detonation and presumably get more power.
Nowadays, I hear some people talking about better gas mileage and maybe power if they use premium gas. Personally, I take the more power part with a grain of salt and a typical care has more power than it needs no matter what it's running on. A Google search says premium is generally 20-25% more expensive than regular and I doubt anybody is getting that big of a mileage increase to justify the cost.
IMO, just look in the little book they gave you, you know, the one you used to setup the radio presets, and find the headlight switch, and see what the manufacturer tells you to use.

[Pat Germain]

The biggest problem with deposits and fouled plugs was from the lead in the gas and carburetors being poor at ideal fuel mixtures especially for rare highway driving. Back in my youth, drag-racing friends used to buy high premium gas across the border in the US because a certain station on the way to the strip had higher octane gas. Idea was to be able to fudge the timing a bit more without pre-detonation and presumably get more power.
Nowadays, I hear some people talking about better gas mileage and maybe power if they use premium gas. Personally, I take the more power part with a grain of salt and a typical care has more power than it needs no matter what it's running on. A Google search says premium is generally 20-25% more expensive than regular and I doubt anybody is getting that big of a mileage increase to justify the cost.
IMO, just look in the little book they gave you, you know, the one you used to setup the radio presets, and find the headlight switch, and see what the manufacturer tells you to use.

Your skepticism is on track. Premium gasoline has no more energy than lower octane gasoline and therefore does not produce more power. 100% gasoline does have more energy per drop than a ethanol blended gasoline. Although, there is some truth to the idea about advancing ignition timing for a little more power and premium gas can allow more ignition timing without pinging. Simply pumping in premium compared to regular gas won't improve MPGs, but pumping in 100% gasoline can improve MPGs compared to an ethanol blend.

Ironically, some very high performance cars run extremely well on E-85 or even 100% ethanol. Those engines are tuned for ethanol. For example, the air/fuel mixture is a lot more rich for ethanol. Ethanol allows for very high compression, but since you have to run the mixture so rich, MPGs suffer big tim.

[Ronald Blue]

The biggest problem with deposits and fouled plugs was from the lead in the gas and carburetors being poor at ideal fuel mixtures especially for rare highway driving. Back in my youth, drag-racing friends used to buy high premium gas across the border in the US because a certain station on the way to the strip had higher octane gas. Idea was to be able to fudge the timing a bit more without pre-detonation and presumably get more power.
Nowadays, I hear some people talking about better gas mileage and maybe power if they use premium gas. Personally, I take the more power part with a grain of salt and a typical care has more power than it needs no matter what it's running on. A Google search says premium is generally 20-25% more expensive than regular and I doubt anybody is getting that big of a mileage increase to justify the cost.
IMO, just look in the little book they gave you, you know, the one you used to setup the radio presets, and find the headlight switch, and see what the manufacturer tells you to use.

While premium is recommended in my torch red mid life crisis two seater it does just fine on an 87 octane 10% ethanol blend. What I find most impressive is that if I drive it without having to feel those 460 HP it will average 30 MPG. It's hard to go for a cruise and not at least tickle the throttle though a few times. I tried premium and saw no improvement either in mileage or performance. It might be something you would have to go to a track to see though.

[Bill George]

Your engine has Knock sensors, when you use a cheaper gas your on board engine computer module ECM adjusts the timing to get rid of the low octane knock before you even hear it. You lose performance of course that you would have with the higher octane fuel. Continued use of low octane may or may not damage your engine.