Gas prices

[imported_Lothar]

Originally posted by: zerocool84

Originally posted by: Lothar

Originally posted by: Eli

Originally posted by: RedSquirrel
What's the main difference between regular and premium as far as driving goes? Like I realize it's higher grade, but does it really make a noticeable performance difference? I always just use regular.

Ahh! It's a good thing I caught this so soon! Otherwise the thread may have spiraled out of control!

It may still.. lol

The difference between the different grades of gasoline is octane rating. Nothing more.

Octane rating is a measure of the fuel's resistance to spontaneously combusting under high heat and pressure. The higher the number, the more resistant it is to this.

There is no performance gain inherent to the gasoline. Infact, higher octane gasoline tends to contain less energy than regular, although they try and keep the difference to 2% or less, through formula variations.

The difference is in the engine. One of the specific characteristics of an engine is it's compression ratio, that is the volume of the cylinder when the piston is at BDC(Bottom Dead Center), compared to the volume at TDC(Top Dead Center).

This is expressed as a ratio, like 10:1. There are other things to take into account when figuring the octane a given engine needs, like combustion chamber design, but it is the compression ratio that matters the most.

The typical compression ratio for an engine that requires Regular is 8.0:1 - 9.0:1. A typical "high performance" engine that needs Premium will run at 9.0:1 - 11.0:1.

By compressing the fuel/air mixture to a higher ratio, you are effectively increasing the efficiency of the engine; it enables the reciprocating mass to extract more energy out of the fuel, which results in a higher specific power output.

So to sum it up, there is no point in using Plus or Premium in an engine that is designed to run on Regular, unless your engine is pinging due to deposits or other factors. But all modern engines have knock sensors, so at least no engine damage will result if there is pinging. However, running high octane fuel in an engine that isn't designed for it can actually increase carbon deposits in the combustion chamber, because of the slower, lower temperature combustion.

So if I buy a BMW that requires premium gas (according to the operating manual) and I decide to put(use) regular instead of the premium that the car requires, what happens?

The computer will adjust for the lower octane gas and your power will go down and you could lose mpg. Remember I said COULD lose mpg.

Which power will go down by and what components will be affected?
If all it does is make me go from 0-60 in 4 seconds rather than 3.8 seconds, I don't think I would care much.


How much possible mpg loss are we talking here?
$39 buys 13 gallons of regular here ($2.99/gal)
That same amount buys about 11 gallons of premium ($3.55/gal)
What about after taking my local prices into account?

 

[zerocool84]

Originally posted by: Lothar

Originally posted by: zerocool84

Originally posted by: Lothar

Originally posted by: Eli

Originally posted by: RedSquirrel
What's the main difference between regular and premium as far as driving goes? Like I realize it's higher grade, but does it really make a noticeable performance difference? I always just use regular.

Ahh! It's a good thing I caught this so soon! Otherwise the thread may have spiraled out of control!

It may still.. lol

The difference between the different grades of gasoline is octane rating. Nothing more.

Octane rating is a measure of the fuel's resistance to spontaneously combusting under high heat and pressure. The higher the number, the more resistant it is to this.

There is no performance gain inherent to the gasoline. Infact, higher octane gasoline tends to contain less energy than regular, although they try and keep the difference to 2% or less, through formula variations.

The difference is in the engine. One of the specific characteristics of an engine is it's compression ratio, that is the volume of the cylinder when the piston is at BDC(Bottom Dead Center), compared to the volume at TDC(Top Dead Center).

This is expressed as a ratio, like 10:1. There are other things to take into account when figuring the octane a given engine needs, like combustion chamber design, but it is the compression ratio that matters the most.

The typical compression ratio for an engine that requires Regular is 8.0:1 - 9.0:1. A typical "high performance" engine that needs Premium will run at 9.0:1 - 11.0:1.

By compressing the fuel/air mixture to a higher ratio, you are effectively increasing the efficiency of the engine; it enables the reciprocating mass to extract more energy out of the fuel, which results in a higher specific power output.

So to sum it up, there is no point in using Plus or Premium in an engine that is designed to run on Regular, unless your engine is pinging due to deposits or other factors. But all modern engines have knock sensors, so at least no engine damage will result if there is pinging. However, running high octane fuel in an engine that isn't designed for it can actually increase carbon deposits in the combustion chamber, because of the slower, lower temperature combustion.

So if I buy a BMW that requires premium gas (according to the operating manual) and I decide to put(use) regular instead of the premium that the car requires, what happens?

The computer will adjust for the lower octane gas and your power will go down and you could lose mpg. Remember I said COULD lose mpg.

Which power will go down by and what components will be affected?
If all it does is make me go from 0-60 in 4 seconds rather than 3.8 seconds, I don't think I would care much.


How much possible mpg loss are we talking here?
$39 buys 13 gallons of regular here ($2.99/gal)
That same amount buys about 11 gallons of premium ($3.55/gal)
What about after taking my local prices into account?

Here's the biggest question, why would you buy a car that requires premium which usually are more expensive than one that doesn't and cheap out on the gas?

 

[rgwalt]

Originally posted by: DrPizza

Originally posted by: spidey07

Originally posted by: DrPizza
:thumbsup: Too bad 90% of people don't realize this.

Hence, my point about supply and demand and high compression engines.

You can't dance around supply/demand.

You sound like a 10th grader who just took an intro to business class. Supply and demand does NOT apply when demand is inelastic. If the price of gasoline was suddenly $10 tomorrow, people would bitch about it and fill up their gas tanks - to the extent that their budget would allow. If they had open credit on their credit cards, they would use credit to purchase gas. Long term, there is some flexibility in demand, but not much.

Price of Coca-cola goes up to $20 a case, and demand will drop dramatically. Price of apples quadruples and demand for apples will drop severely. Price of gasoline triples and people will do what they can do limit their driving, but it's not as if they've been taking the long way to work all these years and suddenly decide to take a shorter route. A few people will be able to work from home, and some people will cancel unnecessary trips. But for the most part, demand for gasoline doesn't vary significantly.

Next lesson: oligopoly. When competition isn't really competition.

Funny, when gasoline tipped $4/gallon over the summer and oil was over $140 a barrel, as a country we saw fairly significant changes in peoples habits. Demand for gasoline was down. People weren't taking unnecessary trips, people were carpooling and taking mass transportation when possible. Granted there is some base level of demand for gasoline / diesel that will not go away unless we are hit with a depression (no jobs to drive to), and even then there will still be some demand. But, look at the bigger picture of oil as a whole... when world economies were all chugging along, demand for oil outpaced the elasticity of the supply of oil, people had money to spend, and prices were driven up. Some of that was speculative, but some was not. Now as world market have melted down and there isn't as much liquidity out there as a whole, demand is down, and so is price. Demand for crude is directly related to the demand for gasoline, diesel, and other petroleum products. As people stop buying gasoline (for whatever reason), prices come down for both gasoline and crude oil.

Maybe the very simple supply vs demand relationship doesn't hold because some percentage of the population must buy fuel in order to get to their job every day, but supply and demand economics do play a part in the price of fuel. If they didn't what would stop refiners from charging $10 for a gallon of gasoline?

R

 

[Elstupido]

No way in hell will I run regular in my 98 BMW V8 with a compression ratio of more than 10.5. True the computer will allow it to run, but believe me, over time the sensors and catalytic converters, etc. will go to hell on you. If you don't want to buy high octane, then don't buy a car that requires it. And requires, has a meaning of compression ratio.

 

[Ronstang]

Originally posted by: Lothar
How much possible mpg loss are we talking here?
$39 buys 13 gallons of regular here ($2.99/gal)
That same amount buys about 11 gallons of premium ($3.55/gal)
What about after taking my local prices into account?

You simply have to test the car and with some models it is best to disconnect the battery long enough to clear the memory on the computer (if that is even possible).

On my Taurus SHO I did enough testing to get solid results and when the spread between regular and premium was still around $.20 a gallon. I definitely had better power and better mileage with the premium fuel but it ended up only saving me $.04 a gallon to drive around with reduced power and potential "pinging" at part throttle load in the summer. That translates into about $.60 a fill up difference. To me it made no sense to have lower power to save less than a buck a tank of gas.

You will have to test your car as the results will likely vary between different types of cars and driving styles.

 

[The Boston Dangler]

Originally posted by: Capt Caveman
My guess is that the high prices of gas has forced people to buy economy over plus/premium. Distributors and gas stations are stuck with a surplus of plus/premium that they bought at higher prices and are still trying to get rid of it, so they won't lower the price or they'll lose money.

nope, it's just price gouging. gas has a dynamic price, right up to the moment you pump it into your car. that's how they justify jacking up the price on the gas that's already in the station's tank.

 

[0roo0roo]

Originally posted by: Lothar

Originally posted by: zerocool84

Originally posted by: Lothar

Originally posted by: Eli

Originally posted by: RedSquirrel
What's the main difference between regular and premium as far as driving goes? Like I realize it's higher grade, but does it really make a noticeable performance difference? I always just use regular.

Ahh! It's a good thing I caught this so soon! Otherwise the thread may have spiraled out of control!

It may still.. lol

The difference between the different grades of gasoline is octane rating. Nothing more.

Octane rating is a measure of the fuel's resistance to spontaneously combusting under high heat and pressure. The higher the number, the more resistant it is to this.

There is no performance gain inherent to the gasoline. Infact, higher octane gasoline tends to contain less energy than regular, although they try and keep the difference to 2% or less, through formula variations.

The difference is in the engine. One of the specific characteristics of an engine is it's compression ratio, that is the volume of the cylinder when the piston is at BDC(Bottom Dead Center), compared to the volume at TDC(Top Dead Center).

This is expressed as a ratio, like 10:1. There are other things to take into account when figuring the octane a given engine needs, like combustion chamber design, but it is the compression ratio that matters the most.

The typical compression ratio for an engine that requires Regular is 8.0:1 - 9.0:1. A typical "high performance" engine that needs Premium will run at 9.0:1 - 11.0:1.

By compressing the fuel/air mixture to a higher ratio, you are effectively increasing the efficiency of the engine; it enables the reciprocating mass to extract more energy out of the fuel, which results in a higher specific power output.

So to sum it up, there is no point in using Plus or Premium in an engine that is designed to run on Regular, unless your engine is pinging due to deposits or other factors. But all modern engines have knock sensors, so at least no engine damage will result if there is pinging. However, running high octane fuel in an engine that isn't designed for it can actually increase carbon deposits in the combustion chamber, because of the slower, lower temperature combustion.

So if I buy a BMW that requires premium gas (according to the operating manual) and I decide to put(use) regular instead of the premium that the car requires, what happens?

The computer will adjust for the lower octane gas and your power will go down and you could lose mpg. Remember I said COULD lose mpg.

Which power will go down by and what components will be affected?
If all it does is make me go from 0-60 in 4 seconds rather than 3.8 seconds, I don't think I would care much.


How much possible mpg loss are we talking here?
$39 buys 13 gallons of regular here ($2.99/gal)
That same amount buys about 11 gallons of premium ($3.55/gal)
What about after taking my local prices into account?

i remember popular mechanics had an issue on this. mpg loss was minimal if any...it was a while back.

 

[woodie1]

Naturally, all these people telling you to not use 91 octane when the manufacturer specifies it will warrant your car when the manufacturer won't honor the warranty. Think I'm kidding - NOT. You could get by with 89 but not 87 or as said above why by a car that uses 91 if you're going to cheap out on the fuel.

 

[Jeff7181]

Maybe someone has been smart enough to mention it but I'm too lazy to read all the posts...

Back when regular was $1/gal, plus was $1.10 and premium was $1.20
Now that regular costs about 300% more, is it any surprise that the price of plus and premium increased by 300% as well?

 

[ElFenix]

Originally posted by: rgwalt
Maybe the very simple supply vs demand relationship doesn't hold because some percentage of the population must buy fuel in order to get to their job every day

R

yeah it does, you just get a kink and a straighter line than you might usually see.


another thing: the supply of oil and gasoline are both short run inelastic as well, especially going outward. so you've got short run rather inelastic demand, and short run inelastic supply, which means that very small changes in either means big price swings.

and oil has been that way for decades.

 

[T9D]

...

 

[MartyMcFly3]

My question, and it may be simple for you all to answer, is as follows:

Why are the brand name gas companies like BP Amoco, Shell, Speedway, etc. at $3.39 a gallon when gas stations at grocery stores like Dominick's, Meijer's, Jewel-Osco, Walmart, etc. are at $2.89? Is it the quality of gas? Have to do with the octane?

 

[zerocool84]

Originally posted by: MartyMcFly3
My question, and it may be simple for you all to answer, is as follows:

Why are the brand name gas companies like BP Amoco, Shell, Speedway, etc. at $3.39 a gallon when gas stations at grocery stores like Dominick's, Meijer's, Jewel-Osco, Walmart, etc. are at $2.89? Is it the quality of gas? Have to do with the octane?

Damn there's that much of a difference between the two??? I've never seen that large of a difference. It's usually just a couple cents from what I've seen.

 

[Jeff7181]

Originally posted by: MartyMcFly3
My question, and it may be simple for you all to answer, is as follows:

Why are the brand name gas companies like BP Amoco, Shell, Speedway, etc. at $3.39 a gallon when gas stations at grocery stores like Dominick's, Meijer's, Jewel-Osco, Walmart, etc. are at $2.89? Is it the quality of gas? Have to do with the octane?

It's mostly in the name. It's the same reason Hostess and Little Debbi snacks cost more than generic brands.

Also, when you buy Shell, you know you're getting Shell. When you buy Meijer, you can be getting gas from any number of suppliers.

 

[LS8]

Filled up this morning for $2.70/gal.

 

[Capt Caveman]

Originally posted by: 0roo0roo

Originally posted by: Lothar

Originally posted by: zerocool84

Originally posted by: Lothar

Originally posted by: Eli

Originally posted by: RedSquirrel
What's the main difference between regular and premium as far as driving goes? Like I realize it's higher grade, but does it really make a noticeable performance difference? I always just use regular.

Ahh! It's a good thing I caught this so soon! Otherwise the thread may have spiraled out of control!

It may still.. lol

The difference between the different grades of gasoline is octane rating. Nothing more.

Octane rating is a measure of the fuel's resistance to spontaneously combusting under high heat and pressure. The higher the number, the more resistant it is to this.

There is no performance gain inherent to the gasoline. Infact, higher octane gasoline tends to contain less energy than regular, although they try and keep the difference to 2% or less, through formula variations.

The difference is in the engine. One of the specific characteristics of an engine is it's compression ratio, that is the volume of the cylinder when the piston is at BDC(Bottom Dead Center), compared to the volume at TDC(Top Dead Center).

This is expressed as a ratio, like 10:1. There are other things to take into account when figuring the octane a given engine needs, like combustion chamber design, but it is the compression ratio that matters the most.

The typical compression ratio for an engine that requires Regular is 8.0:1 - 9.0:1. A typical "high performance" engine that needs Premium will run at 9.0:1 - 11.0:1.

By compressing the fuel/air mixture to a higher ratio, you are effectively increasing the efficiency of the engine; it enables the reciprocating mass to extract more energy out of the fuel, which results in a higher specific power output.

So to sum it up, there is no point in using Plus or Premium in an engine that is designed to run on Regular, unless your engine is pinging due to deposits or other factors. But all modern engines have knock sensors, so at least no engine damage will result if there is pinging. However, running high octane fuel in an engine that isn't designed for it can actually increase carbon deposits in the combustion chamber, because of the slower, lower temperature combustion.

So if I buy a BMW that requires premium gas (according to the operating manual) and I decide to put(use) regular instead of the premium that the car requires, what happens?

The computer will adjust for the lower octane gas and your power will go down and you could lose mpg. Remember I said COULD lose mpg.

Which power will go down by and what components will be affected?
If all it does is make me go from 0-60 in 4 seconds rather than 3.8 seconds, I don't think I would care much.


How much possible mpg loss are we talking here?
$39 buys 13 gallons of regular here ($2.99/gal)
That same amount buys about 11 gallons of premium ($3.55/gal)
What about after taking my local prices into account?

i remember popular mechanics had an issue on this. mpg loss was minimal if any...it was a while back.

While driving cross-country, I experimented with regular instead of Premium(recommended for my car). I lost about 2mpg using regular.

 

[DrPizza]

Originally posted by: rgwalt

Originally posted by: DrPizza

Originally posted by: spidey07

Originally posted by: DrPizza
:thumbsup: Too bad 90% of people don't realize this.

Hence, my point about supply and demand and high compression engines.

You can't dance around supply/demand.

You sound like a 10th grader who just took an intro to business class. Supply and demand does NOT apply when demand is inelastic. If the price of gasoline was suddenly $10 tomorrow, people would bitch about it and fill up their gas tanks - to the extent that their budget would allow. If they had open credit on their credit cards, they would use credit to purchase gas. Long term, there is some flexibility in demand, but not much.

Price of Coca-cola goes up to $20 a case, and demand will drop dramatically. Price of apples quadruples and demand for apples will drop severely. Price of gasoline triples and people will do what they can do limit their driving, but it's not as if they've been taking the long way to work all these years and suddenly decide to take a shorter route. A few people will be able to work from home, and some people will cancel unnecessary trips. But for the most part, demand for gasoline doesn't vary significantly.

Next lesson: oligopoly. When competition isn't really competition.

Funny, when gasoline tipped $4/gallon over the summer and oil was over $140 a barrel, as a country we saw fairly significant changes in peoples habits. Demand for gasoline was down. People weren't taking unnecessary trips, people were carpooling and taking mass transportation when possible. Granted there is some base level of demand for gasoline / diesel that will not go away unless we are hit with a depression (no jobs to drive to), and even then there will still be some demand. But, look at the bigger picture of oil as a whole... when world economies were all chugging along, demand for oil outpaced the elasticity of the supply of oil, people had money to spend, and prices were driven up. Some of that was speculative, but some was not. Now as world market have melted down and there isn't as much liquidity out there as a whole, demand is down, and so is price. Demand for crude is directly related to the demand for gasoline, diesel, and other petroleum products. As people stop buying gasoline (for whatever reason), prices come down for both gasoline and crude oil.

Maybe the very simple supply vs demand relationship doesn't hold because some percentage of the population must buy fuel in order to get to their job every day, but supply and demand economics do play a part in the price of fuel. If they didn't what would stop refiners from charging $10 for a gallon of gasoline?

R

Funny that at that time, they had some of the largest stockpiles of gasoline too... Supply was way up, demand was somewhat lower, yet prices continued to soar.

 

[kalrith]

On a side note, E-85 here is Missouri is now only 10 cents cheaper than 87 octane. Even with a flex fuel vehicle, the cost per mile would be higher for E-85 than 87 octane.

 

[Eeezee]

Originally posted by: Capt Caveman
My guess is that the high prices of gas has forced people to buy economy over plus/premium. Distributors and gas stations are stuck with a surplus of plus/premium that they bought at higher prices and are still trying to get rid of it, so they won't lower the price or they'll lose money.

Then they fail at economics; by keeping the price higher, even fewer people are going to buy it (ie they lowered demand by keeping the price high) and the gas is just going to sit around, not being sold to anyone.

I guess they'll eventually get rid of it when prices go back up, but in the meantime they're taking a profit hit.

 

[Capt Caveman]

Originally posted by: Eeezee

Originally posted by: Capt Caveman
My guess is that the high prices of gas has forced people to buy economy over plus/premium. Distributors and gas stations are stuck with a surplus of plus/premium that they bought at higher prices and are still trying to get rid of it, so they won't lower the price or they'll lose money.

Then they fail at economics; by keeping the price higher, even fewer people are going to buy it (ie they lowered demand by keeping the price high) and the gas is just going to sit around, not being sold to anyone.

I guess they'll eventually get rid of it when prices go back up, but in the meantime they're taking a profit hit.

How are they taking a profit hit? They're selling regular instead of premium, making a profit. If they lowered the price of premium, they'd lose money. Sure, they would get rid of it sooner but then they'd just be selling the premium at a lower price making the same profit amount(only a few cents a gallon).

Note - they're still selling premium but not as much as they would normally.

 

[rgwalt]

Originally posted by: Jeff7181

Originally posted by: MartyMcFly3
My question, and it may be simple for you all to answer, is as follows:

Why are the brand name gas companies like BP Amoco, Shell, Speedway, etc. at $3.39 a gallon when gas stations at grocery stores like Dominick's, Meijer's, Jewel-Osco, Walmart, etc. are at $2.89? Is it the quality of gas? Have to do with the octane?

It's mostly in the name. It's the same reason Hostess and Little Debbi snacks cost more than generic brands.

Also, when you buy Shell, you know you're getting Shell. When you buy Meijer, you can be getting gas from any number of suppliers.

Actually, this isn't true anymore... gasoline is a fungible commodity, meaning that each refiner produces it to some set of minimum specifications (as set by the EPA and the API). When you buy Shell gas, you could be buying gasoline that was produced at a refinery owned by Exxon, BP, Chevron, Citgo, or any number of other companies. It is cheaper for Shell to buy gasoline from a local supplier than pipe it all over the country from its various refineries... The difference is that when you buy Shell gas, you do get Shell's additive package.

R