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View Full Version : Which of the 3 gas grades do you buy?


dogsballs
04-26-2005, 10:34 PM
At the gas station to fill up, what do you pick?

I don't know the details but I've been told that the better grades get more performance and efficiency from your vehicle, and less engine wear/problems. No idea how to quantify it but since it's only 10c between grades, I just stick the best one in my '89 beater Chevy pickup.

TStoneMBD
04-26-2005, 10:35 PM
ive been told that if you buy the 93 stuff that it actually damages your car. dont know how true that is though.

Reef
04-26-2005, 10:35 PM
only the best for my baby

tbach24
04-26-2005, 10:36 PM
Where's the "I Don't Have a Permit yet" option?

Reef
04-26-2005, 10:36 PM
[ QUOTE ]
ive been told that if you buy the 93 stuff that it actually damages your car. dont know how true that is though.

[/ QUOTE ]

I've been told a lot of stuff as well. Not all of it is true.

Sponger15SB
04-26-2005, 10:36 PM
[ QUOTE ]
ive been told that if you buy the 93 stuff that it actually damages your car

[/ QUOTE ]

Well, if you buy the 93 stuff and your car isn't reccomended to have it.

Reef
04-26-2005, 10:36 PM
[ QUOTE ]
Where's the "I Don't Have a Permit yet" option?

[/ QUOTE ]

sucks to be you

Sponger15SB
04-26-2005, 10:38 PM
[ QUOTE ]
[ QUOTE ]
ive been told that if you buy the 93 stuff that it actually damages your car. dont know how true that is though.

[/ QUOTE ]

I've been told a lot of stuff as well. Not all of it is true.

[/ QUOTE ]

http://www.straightdope.com/columns/041008.html

Dead
04-26-2005, 10:40 PM
[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
ive been told that if you buy the 93 stuff that it actually damages your car. dont know how true that is though.

[/ QUOTE ]

I've been told a lot of stuff as well. Not all of it is true.

[/ QUOTE ]

http://www.straightdope.com/columns/041008.html

[/ QUOTE ]

From that link:

"Using high-octane gas in a car designed for regular accomplishes little except more rapid combustion of your money. Some refuse to believe this, claiming, for example, that premium gives the family Toyota better mileage or more power. These people are on drugs."

That made me laugh Sponge.

jason_t
04-26-2005, 10:40 PM
[ QUOTE ]
ive been told that if you buy the 93 stuff that it actually damages your car. dont know how true that is though.

[/ QUOTE ]

This depends on your car, but for most cars this is correct. It will cause a knocking sound.

shadow29
04-26-2005, 10:40 PM
super ultra premium.

daryn
04-26-2005, 10:41 PM
people who buy more expensive gas when less expensive gas is less than 6 inches away make me laugh.

tbach24
04-26-2005, 10:42 PM
[ QUOTE ]
super duper ultra mega legit premium.

[/ QUOTE ]

fyp

jason_t
04-26-2005, 10:45 PM
It's not about what type you feel like spending money on. Each car is designed to take a certain octane. My 2004 Honda Civic requires gas with 87--89 octane which in most states is regular but in Utah, for example, it's the middle one.

More expensive gas doesn't give you better gas mileage, it doesn't make your car run better and doesn't burn cleaner.

purnell
04-26-2005, 10:45 PM
I don't think my '91 sentra would run any better on high octane gas. I really don't think it could run any better, period. 150k miles, and I swear she has NEVER let me down.

mostsmooth
04-26-2005, 10:45 PM
[ QUOTE ]
[ QUOTE ]
ive been told that if you buy the 93 stuff that it actually damages your car. dont know how true that is though.

[/ QUOTE ]

This depends on your car, but for most cars this is correct. It will cause a knocking sound.

[/ QUOTE ]
i disagree. higher octane does not cause knocking, it prevents it.

jason_t
04-26-2005, 10:48 PM
[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
ive been told that if you buy the 93 stuff that it actually damages your car. dont know how true that is though.

[/ QUOTE ]

This depends on your car, but for most cars this is correct. It will cause a knocking sound.

[/ QUOTE ]
i disagree. higher octane does not cause knocking, it prevents it.

[/ QUOTE ]

What I said is incorrect. Using a lower octane that what your car needs will cause knocking.

mostsmooth
04-26-2005, 10:50 PM
[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
ive been told that if you buy the 93 stuff that it actually damages your car. dont know how true that is though.

[/ QUOTE ]

This depends on your car, but for most cars this is correct. It will cause a knocking sound.

[/ QUOTE ]
i disagree. higher octane does not cause knocking, it prevents it.

[/ QUOTE ]

What I said is incorrect. Using a lower octane that what your car needs will cause knocking.

[/ QUOTE ]
i agree.

theredwave
04-26-2005, 10:51 PM
I would use ethanol if my car would allow it, but I have to use regular unleaded instead. Also, diesel should be included in the list in case someone drives a large truck.

Dead
04-26-2005, 10:51 PM
Stop nitpicking.

Does it make you feel smarter to correct him?

You knew what he meant.

I'm kicking you out of the Yankee fan club, and banishing you to the Padres fan club.

peachy
04-26-2005, 10:52 PM
top of the line for mah baby

purnell
04-26-2005, 10:52 PM
[ QUOTE ]
[ QUOTE ]
ive been told that if you buy the 93 stuff that it actually damages your car. dont know how true that is though.

[/ QUOTE ]

This depends on your car, but for most cars this is correct. It will cause a knocking sound.

[/ QUOTE ]

No, using gas with too LOW an octane rating causes knocking (the knocking sound is the gas/air mix exploding in the cylinder too soon). "Octane", which is kind of a misnomer, is a rating of the fuel's ability to resist premature combustion due to high pressure. Thus high "octane" is required for engines that have a high compression ratio.

Non_Comformist
04-26-2005, 10:57 PM
[ QUOTE ]


I'm kicking you out of the Yankee fan club, and banishing you to the Padres fan club.

[/ QUOTE ]

Also known as The Haters Club (Pfunk I'm looking at you)

mostsmooth
04-26-2005, 10:58 PM
[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
ive been told that if you buy the 93 stuff that it actually damages your car. dont know how true that is though.

[/ QUOTE ]

This depends on your car, but for most cars this is correct. It will cause a knocking sound.

[/ QUOTE ]

No, using gas with too LOW an octane rating causes knocking (the knocking sound is the gas/air mix exploding in the cylinder too soon). "Octane", which is kind of a misnomer, is a rating of the fuel's ability to resist premature combustion due to high pressure. Thus high "octane" is required for engines that have a high compression ratio.

[/ QUOTE ]
Stop nitpicking.

Does it make you feel smarter to correct him?

You knew what he meant.

I'm kicking you out of the Yankee fan club, and banishing you to the Padres fan club.

Dead
04-26-2005, 11:02 PM
[ QUOTE ]
[ QUOTE ]


I'm kicking you out of the Yankee fan club, and banishing you to the Padres fan club.

[/ QUOTE ]

Also known as The Haters Club (Pfunk I'm looking at you)

[/ QUOTE ]

Did you know that A-Rod doesn't hit with runners in scoring position? That's why he was 4-4 tonight with RISP.

Baseball Tonight has spent 20 minutes talking about A-Rod's game. That must be because it's "pointless". /images/graemlins/tongue.gif

jason_t
04-26-2005, 11:17 PM
[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
ive been told that if you buy the 93 stuff that it actually damages your car. dont know how true that is though.

[/ QUOTE ]

This depends on your car, but for most cars this is correct. It will cause a knocking sound.

[/ QUOTE ]

No, using gas with too LOW an octane rating causes knocking (the knocking sound is the gas/air mix exploding in the cylinder too soon). "Octane", which is kind of a misnomer, is a rating of the fuel's ability to resist premature combustion due to high pressure. Thus high "octane" is required for engines that have a high compression ratio.

[/ QUOTE ]

I've already elaborated on what I meant to say.

jason_t
04-26-2005, 11:18 PM
[ QUOTE ]
top of the line for mah baby

[/ QUOTE ]

What do you drive. You may be needlessly wasting money.

Roan
04-26-2005, 11:23 PM
i hate when they switch the cheap one to the middle to try and trick you

theredwave
04-26-2005, 11:25 PM
[ QUOTE ]
i hate when they switch the cheap one to the middle to try and trick you

[/ QUOTE ]

Yes, cause reading is really hard.

Freakin
04-26-2005, 11:25 PM
To clarify and expand slightly on what Cecil said,

Octane rating is a measure of the amount of Octanol in teh gasoline. Octanol is an extremely stable hydrocarbon. It is mixed with another hydrocarbon (heptanol or something) which is less stable. The higher the octane rating, the more stable octanol in teh gasoline.

A higher performance car manufacturer realizes that if he compresses the gas more, he can get more power from it. If a gas is compressed too much, it will combust. Using a higher octane gas allows you to compress the gas more, and get more power from it. It will not necessarily burn any cleaner or dirtier. As he says, it only serves to waste money, and will not benefit your car at all*.

To use a cheaper gas in a more expensive car that requires higher octane gas is stupid. While it may not knock continually, it will occasionally. The gas is simply not recommended for the level of compression needed.

*Some higher octane gasolines also have additional fuel additives that can benefit your car.

Freakin

Reef
04-26-2005, 11:28 PM
[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
ive been told that if you buy the 93 stuff that it actually damages your car. dont know how true that is though.

[/ QUOTE ]

I've been told a lot of stuff as well. Not all of it is true.

[/ QUOTE ]

http://www.straightdope.com/columns/041008.html

[/ QUOTE ]

I don't disagree that using a different grade than recommended can be damaging. However, the OP was making a wide-sweeping statement with which I confirmed his doubt in.

Ringo_Mojo
04-26-2005, 11:46 PM
Yeah the gas companies don't like to admit it but there is no advantage to using higher octaine gas then what the manufacturer recommends. Check your car's user manual to find out what you should be using.

Another thing they don't like to admit is that all the gas in an area is the same. All the gas companies use the same pipes to transport the fuel across the country, and they even swap fuel between themselves. The only actual difference between the expensive name brand gas and the cheap generic gas is which additives they use at the company depot.

Patrick del Poker Grande
04-26-2005, 11:52 PM
Wow. I'm amazed how misguided so many people are about octane ratings. It's also interesting because I just went through this with my wife two days ago when she told me she she was putting midgrade in our turbocharged car in order to save money on the higher gas prices. After I [censored] a brick, here's what I told her:

Higher octane gas isn't about fuel efficiency or keeping your engine clean or any of that, although some companies do put additives in their premium fuels that may give marginal improvements in these areas - lubricants or cleaning agents, some hocus-pocus.

Before we go any further, let's recall the 4-stroke engine cycle. If you start at Top Dead Center (TDC), the piston goes down and the fuel/air mixture is drawn into the chamber (step 1). The piston bottoms out and comes back to the top (step 2), which compresses the fuel/air mixture. Remember this point - it's where we run into the issue we're talking about. The spark plug ignites the fuel/air and the explosion drives the piston down through the power stroke (step 3). Then, the piston returns back to the top and drives out the exhaust on its way up (step 4). Now you're back at the start - repeat a few thousand times every minute for best performance.

Now, engines are tuned such that the fuel/air mixture is pretty much ready to explode at the end of step 2. It's not right at the very edge in consumer cars for safety, but in highly tuned race cars, it's right there. If it were to explode too soon, when the piston is still on its way up the compression stroke (#2), the explosion would put a huge load on the piston in the wrong direction and try to blow it backwards when it's trying to come up to the top. As you can imagine, this can be very very bad for your engine and it's very much not optimal for performance. This is knock.

Now imagine that you have higher than normal pressure in your chamber. This is desireable for higher torque and power output. This could be accomplished by large compression ratios (the ratio of the volume in the chamber at BDC over the volume at TDC) or if you have forced induction - a turbocharger or a supercharger. There is a point at which the pressure alone will cause the fuel/air mixture to explode. In fact, this is how a diesel engine works - they have very high compression ratios. If you use regular fuel in an engine operating under very high pressure, you are not unlikely to knock with regular fuel. This is where midgrade and premium fuel come in.

Now, what is Octane rating? The way they solve this problem (now, at least - they used to add lead, which is why we now call our fuel unleaded) is to have more long-chain hydrocarbon molecules in the fuel. These long-chain molecules are harder to ignite and therefore can withstand higher pressures before they'll ignite. It's escaping me right now exactly what the numbers mean in the Octane rating, but a higher octane rating means the fuel has a higher percentage of these longer chain molecules and is more resistant to ignition.

PREVENTION OF KNOCK IN FORCED INDUCTION (turbo- or supercharged) OR HIGH COMPRESSION RATIO ENGINES IS THE ONLY BENEFIT OF HIGHER OCTAN RATING. Some engines also will knock under heavy load - think pulling a boat up a mountain. Extra additives may add other marginal benefits in some premium brand fuels, but again, this is marginal and is not the real reason to buy premium fuel.

If you have a 'normal' vehicle with a normally aspirated engine, you get NO benefit from buying anything other than regular fuel. None. It doesn't hurt the car any, but it hurts your wallet. If you have a turbocharged car, you better be using premium fuel. You can probably get away with midgrade, but don't go pushing it hard.

Ianco15
04-27-2005, 12:38 AM
I am almost 100% sure that no car was designed to run on specifically on mid-grade fuel. Someone show me a car that is and I'll shut my mouth.

Alobar
04-27-2005, 12:38 AM
I havent read the replies, so maybe someone mentions it. But its actually cheaper for me to buy the expensive stuff, because I get a higher MPG than I do with the cheap stuff, and so I get farther on a tank of gas. I worked that math one time, and found it was more cost effective to get the premium, so thats what I get.

edited to add: neet, now I read the replies and im adding this because so many people say it doesnt make a difference. If it doesnt make a difference, then how come I get a higher MPG with the premium? Sample size isnt much of an issue either, cuz Ive run god knows how many tanks of each, and im anal about trackingmy fuel milage.

Ianco15
04-27-2005, 12:42 AM
[ QUOTE ]
I havent read the replies, so maybe someone mentions it. But its actually cheaper for me to buy the expensive stuff, because I get a higher MPG than I do with the cheap stuff, and so I get farther on a tank of gas. I worked that math one time, and found it was more cost effective to get the premium, so thats what I get.

[/ QUOTE ]
If you had read the replies you would see that it has been proven that this theory is wrong (assuming your car is not designed for premium).

apd138
04-27-2005, 12:42 AM
[ QUOTE ]
I am almost 100% sure that no car was designed to run on specifically on mid-grade fuel. Someone show me a car that is and I'll shut my mouth.

[/ QUOTE ] My buddies hemi takes midgrade I dont know what you mean by "designed for" but many cars are "supposed" to take it.

Ianco15
04-27-2005, 12:46 AM
[ QUOTE ]
[ QUOTE ]
I am almost 100% sure that no car was designed to run on specifically on mid-grade fuel. Someone show me a car that is and I'll shut my mouth.

[/ QUOTE ] My buddies hemi takes midgrade I dont know what you mean by "designed for" but many cars are "supposed" to take it.

[/ QUOTE ]
How do you know? Every car is "designed" to take a certain octane, set by the manufacturer. I have never seen one that is "designed" to take mid-grade.

BTW it says which octane the vehicle is designed to take in the owner's manual.

astroglide
04-27-2005, 01:53 AM
my car needs premium so that's what i use. people that put higher grades of gas in engines that don't ask for it are retarded.

gvibes
04-27-2005, 01:58 AM
I'm pretty sure Mr. Cowbell is correct on this one.

Freakin
04-27-2005, 03:45 AM
[ QUOTE ]
I havent read the replies, so maybe someone mentions it. But its actually cheaper for me to buy the expensive stuff, because I get a higher MPG than I do with the cheap stuff, and so I get farther on a tank of gas. I worked that math one time, and found it was more cost effective to get the premium, so thats what I get.

edited to add: neet, now I read the replies and im adding this because so many people say it doesnt make a difference. If it doesnt make a difference, then how come I get a higher MPG with the premium? Sample size isnt much of an issue either, cuz Ive run god knows how many tanks of each, and im anal about trackingmy fuel milage.

[/ QUOTE ]

Fuel additives, presumably. Try using the cheaper stuff and getting a bottle of STP fuel additive and seeing what that does.

Freakin

zephed56
04-27-2005, 08:32 AM
[ QUOTE ]
I havent read the replies, so maybe someone mentions it. But its actually cheaper for me to buy the expensive stuff, because I get a higher MPG than I do with the cheap stuff, and so I get farther on a tank of gas. I worked that math one time, and found it was more cost effective to get the premium, so thats what I get.

edited to add: neet, now I read the replies and im adding this because so many people say it doesnt make a difference. If it doesnt make a difference, then how come I get a higher MPG with the premium? Sample size isnt much of an issue either, cuz Ive run god knows how many tanks of each, and im anal about trackingmy fuel milage.

[/ QUOTE ]
Stop doing burnouts out of the gas station after you fill up with regular, that will help.

dabluebery
04-27-2005, 09:35 AM
[ QUOTE ]
Wow. I'm amazed how misguided so many people are about octane ratings. It's also interesting because I just went through this with my wife two days ago when she told me she she was putting midgrade in our turbocharged car in order to save money on the higher gas prices. After I [censored] a brick, here's what I told her:

Higher octane gas isn't about fuel efficiency or keeping your engine clean or any of that, although some companies do put additives in their premium fuels that may give marginal improvements in these areas - lubricants or cleaning agents, some hocus-pocus.

Before we go any further, let's recall the 4-stroke engine cycle. If you start at Top Dead Center (TDC), the piston goes down and the fuel/air mixture is drawn into the chamber (step 1). The piston bottoms out and comes back to the top (step 2), which compresses the fuel/air mixture. Remember this point - it's where we run into the issue we're talking about. The spark plug ignites the fuel/air and the explosion drives the piston down through the power stroke (step 3). Then, the piston returns back to the top and drives out the exhaust on its way up (step 4). Now you're back at the start - repeat a few thousand times every minute for best performance.

Now, engines are tuned such that the fuel/air mixture is pretty much ready to explode at the end of step 2. It's not right at the very edge in consumer cars for safety, but in highly tuned race cars, it's right there. If it were to explode too soon, when the piston is still on its way up the compression stroke (#2), the explosion would put a huge load on the piston in the wrong direction and try to blow it backwards when it's trying to come up to the top. As you can imagine, this can be very very bad for your engine and it's very much not optimal for performance. This is knock.

Now imagine that you have higher than normal pressure in your chamber. This is desireable for higher torque and power output. This could be accomplished by large compression ratios (the ratio of the volume in the chamber at BDC over the volume at TDC) or if you have forced induction - a turbocharger or a supercharger. There is a point at which the pressure alone will cause the fuel/air mixture to explode. In fact, this is how a diesel engine works - they have very high compression ratios. If you use regular fuel in an engine operating under very high pressure, you are not unlikely to knock with regular fuel. This is where midgrade and premium fuel come in.

Now, what is Octane rating? The way they solve this problem (now, at least - they used to add lead, which is why we now call our fuel unleaded) is to have more long-chain hydrocarbon molecules in the fuel. These long-chain molecules are harder to ignite and therefore can withstand higher pressures before they'll ignite. It's escaping me right now exactly what the numbers mean in the Octane rating, but a higher octane rating means the fuel has a higher percentage of these longer chain molecules and is more resistant to ignition.

PREVENTION OF KNOCK IN FORCED INDUCTION (turbo- or supercharged) OR HIGH COMPRESSION RATIO ENGINES IS THE ONLY BENEFIT OF HIGHER OCTAN RATING. Some engines also will knock under heavy load - think pulling a boat up a mountain. Extra additives may add other marginal benefits in some premium brand fuels, but again, this is marginal and is not the real reason to buy premium fuel.

If you have a 'normal' vehicle with a normally aspirated engine, you get NO benefit from buying anything other than regular fuel. None. It doesn't hurt the car any, but it hurts your wallet. If you have a turbocharged car, you better be using premium fuel. You can probably get away with midgrade, but don't go pushing it hard.

[/ QUOTE ]

Um..... this is what you told your wife? All of it? I'm picturing you with charts, and overhead transparencies / a powerpoint presentation, and your wife asleep in 5 seconds.

To add to the discussion, I had a Ford Taurus for a while with a real dirty engine that knocked if I used less than 89, so I bought it, just to keep it from knocking. But I do what the manual says unless I have a problem.
Rob

BiffMan
04-27-2005, 09:43 AM
A little OT, but talking about the 4-stroke engine cycle reminded me that I still can't wrap my brain around the amazing engineering that results in engines that can handle 12,000+ RPM like in F1 or Indycar engines. That's 200+ full 4 stroke rotations per *second*... That level of precision with that many moving parts has always amazed me...

apd138
04-27-2005, 09:44 AM
[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
I am almost 100% sure that no car was designed to run on specifically on mid-grade fuel. Someone show me a car that is and I'll shut my mouth.

[/ QUOTE ] My buddies hemi takes midgrade I dont know what you mean by "designed for" but many cars are "supposed" to take it.

[/ QUOTE ]
How do you know? Every car is "designed" to take a certain octane, set by the manufacturer. I have never seen one that is "designed" to take mid-grade.

BTW it says which octane the vehicle is designed to take in the owner's manual.

[/ QUOTE ] That would be the place you would find most info about said vehicle.

beerbandit
04-27-2005, 10:00 AM
some people dont know what 6 inches is either

beerbandit
04-27-2005, 10:02 AM
i think its funny also when theyll drive a mile out of the way to save $.02 per gallon

jakethebake
04-27-2005, 10:02 AM
I usually put the good stuff in mine.

My wife's specifically says to use only the cheap stuff. I like it.

mostsmooth
04-27-2005, 10:38 AM
[ QUOTE ]
A little OT, but talking about the 4-stroke engine cycle reminded me that I still can't wrap my brain around the amazing engineering that results in engines that can handle 12,000+ RPM like in F1 or Indycar engines. That's 200+ full 4 stroke rotations per *second*... That level of precision with that many moving parts has always amazed me...

[/ QUOTE ]
its ~200 revs per sec, when you say "full 4 stroke rotations", are you thinking a rev = a complete cylinder cycle?
just curious
/images/graemlins/cool.gif

dabluebery
04-27-2005, 10:39 AM
Along these lines, I HATE it when people talk about what a POS their car is because it broke down once or twice while they had it. It's like.....

Do you know how many millions of things happened without incident, just so your car could make it from your house to work today?

Rob

jakethebake
04-27-2005, 10:41 AM
[ QUOTE ]
Along these lines, I HATE it when people talk about what a POS their car is because it broke down once or twice while they had it. It's like.....

Do you know how many millions of things happened without incident, just so your car could make it from your house to work today?

Rob

[/ QUOTE ]

This logic is retarted.

Lazymeatball
04-27-2005, 11:04 AM
Ok, so I drive a 95 Subaru Impreza, my daily commute is probably around 3 or 4 miles each way, pretty low, and it gets pretty good gas mileage.

I fill up every 2 or 3 weeks with the middle grade. I don't know why I pick the middle grade, but I figure my car isn't a huge gas guzzler anyway and I don't travel very far, so why not treat her nice.

So I havn't read my owners manual lately, but is it safe to assume that it would recomend the lowest octane rating (based on your knowledge of the average 10 year old japaneese econo-box)?

Am i doing any harm by getting the middle grade, apart from the extra 10 cents per gallon, which isn't even that much based on the good gas mileage my car gets, and the low amount of driving I do?

mistrpug
04-27-2005, 11:29 AM
[ QUOTE ]
ive been told that if you buy the 93 stuff that it actually damages your car. dont know how true that is though.

[/ QUOTE ]

When I bought my car in January, the dealer told me that using anything other than 87 (the cheap one) damages the car and I think he even says it voids the warranty.

jakethebake
04-27-2005, 12:08 PM
[ QUOTE ]
When I bought my car in January, the dealer told me that using anything other than 87 (the cheap one) damages the car and I think he even says it voids the warranty.

[/ QUOTE ]

That's what it says in my wife's owner's manual. But it doesn't void the warranty.