if you use premium gas your eccentric

[PAUL M]

Interesting article
I guess I'm eccentric:biggrin:

http://www.sciam.com/article.cfm?chanId=sa003&articleId=373086C9-E7F2-99DF-385F3705197C1D4F

 

[H-carWizKid]

My ex-girlfriend and I covered this once- she was a die hard 86 octane buyer, and i have always gone with premium. She drives a 4x4 toyota 4 runner

Here is how she was made to be a believer.

As good boyfriends do, I helped her out by arranging a full tune-up of the engine, drivetrain, and 4x4 components since the vehicle was higher milage and it had only seen sporatic maintainence since she had bought it new.

We had the conversation several times of the benefit of premium vs regular, so we ran an experiment. What would be the difference if she switched?

The Baseline-

We started keeping track of her fuel usage- taking a the amount she put in the tank, and dividing it by the number of miles since her last fill up. After 3 or 4 tanks of regular we calculated that she was averaging 17 mpg on her daily commute.

Then we switched to premium

after a few tanks fuel milage showed an improvement of 2 mpg, and sometimes 3- but we saw an improvement.

on an average fill-up she was purchasing 16 gallons of gas so this improvement was somewhere in the neighborhood of 32 miles per tank.

32 That = approx 2 of the old gallons

fuel prices at the time were

2.60 regular
2.72 mid
2.85 premium

So what is better?

Paying out an additional .25 per gallon and getting the extra 32 miles out of the tank, or saving that money up front and ultimately paying out and additional $5.20 because you are using more gas to accomplish the equivilent milage per tank?

The breakdown on a 16 gallon fillup is that it cost $4.00 to upgrade to premium and get the better milage. It cost an additional $5.20 to go the equivilent number of miles on regular

Her savings buying the cheap stuff?

-$1.20

She buys premium now.

Philip

 

[robr]

Better gas mileage in a 4x4 toyota 4 runner from using premium fuel? I call shenanigans.

 

[H-carWizKid]

Better gas mileage in a 4x4 toyota 4 runner from using premium fuel? I call shenanigans.

ok.

I showed the math, how do you recommend I prove it?

Why not run the experiment on your own? You CAN afford $4.00 extra dollars for a couple of fill ups right?

Go get a fresh oil change and run your nice new G35 on regular for 4 tanks, than run it on premium for four tanks- keep track of the milage

Give it an honest effort - I bet you see an improvement.

Philip

P.S I Sent Lauren a link to the thread so she could see you calling me a liar- I'm sure she will LOVE that.

LOL

 

[Klayton]

she was a die hard 86 octane buyer, and i have always gone with premium.

Just curious, 86 octane is the 'normal gas' you buy in the US?

Klayton

 

[Tom239]

Just curious, 86 octane is the 'normal gas' you buy in the US?

Klayton

Octane ratings in the USA are the average of the research and motor octane ratings, (R+M)/2, and are not directly comparable to ratings in countries that just cite the research octane (RON) number.

Typical ratings vary by region. Regular is 87 where I live.

 

[H-carWizKid]

Just curious, 86 octane is the 'normal gas' you buy in the US?

Klayton

It was in Denver where Lauren lived at the time.

 

[robr]

The G35 requires premium so it wouldn't really work with that car. It's not like this hasn't been covered to death, every paper and test I've read on this subject over the past 2 decades has again and again said that if your car does not require a premium fuel, there are zero benefits from using premium. This is probably the very first time I've seen otherwise and have seen data attached.

 

[mohaji]

The G35 requires premium so it wouldn't really work with that car. It's not like this hasn't been covered to death, every paper and test I've read on this subject over the past 2 decades has again and again said that if your car does not require a premium fuel, there are zero benefits from using premium. This is probably the very first time I've seen otherwise and have seen data attached.

Hi Rob,

I've read probably the same stuff as you regarding the benefits/cost of premium and regular gas on cars that only requires regular stuff, but I have to side with Philip on his empirical result.
I've done the same test on my own using my car last year, and Premium did improve MPG quite a bit.
Granted, it was an old car(like the 4x4 used for testing by Philip) whose engine could probably benefit more from premium vs brand new car, but still the improvements were there.

Regards,

 

[H-carWizKid]

The G35 requires premium so it wouldn't really work with that car.

I thought there wasn't any difference? :wink:

Here is Laurens response via email after she read this thread. :biggrin:

You speak the truth!

Not only did I get better gas mileage, I could FEEL the difference in the performance. Living in Denver, the land-o-mountains, I could absolutely tell that my 4 Runner accelerated MUCH better up the mountains and just in general driving on the interstate.

Tell Mr. "robr" that I disagree completely with his belief that there are "zero benefits from using premium"!!!

Do what you gotta do, my findings have demonstrated an advantage to running premium that satisfies my decision making paradigm.

It is all in the way you quantify the data.


Philip

 

[robr]

I clearly did NOT say there was no difference between premium gas and regular gas, you're putting words into my mouth. I stated that everything I've read on this subject indicates there is no difference when premium is used in a car that does not require premium.

http://www.edmunds.com/advice/fueleconomy/articles/106293/article.html
http://www.straightdope.com/columns/041008.html
http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm
http://www.usatoday.com/money/autos/2003-07-30-premiumgas_x.htm
http://autos.msn.com/advice/CRArt.aspx?contentid=4024120
http://www.madsci.org/posts/archives/2000-12/976499784.Eg.r.html

I cannot find a SINGLE source that confirms your findings. So, maybe for you this works, but I don't think it's valid in general.

And now your ex is saying not only did she get better milage, but she could 'feel' increased accelerations and performance? Now I REALLY call shenanigans.

 

[nchopp]

Now I REALLY call shenanigans.

 

[scorp965]

The problem with this "real world" test is just that, it was not controlled - rather than sit on a dyno and run through the fuel she ran errands, she drove on the freeway, she drove in traffic, perhaps she was late a day and gave the car a bit more gas than typical - point is, fuel mileage varies between tanks based on driving habits, and the fuel savings you describe is easily within such an error margin - if such a fuel savings existed, on a regular and easily measured basis, everybody would know about it.

I don't see how the octane level would positively impact your fuel mileage - some fuel system cleaner sure, perhaps 'chevron with techron', but just a higher octane? Sounds like somebody has a case of the 'premium' placebo effect.

In my case, I use premium (unfortuantly the highest in SoCal is 91 octane) in the nsx, and I use standard (87 octane) in the Leganza.

 

[H-carWizKid]

I clearly did NOT say there was no difference between premium gas and regular gas, you're putting words into my mouth. I stated that everything I've read on this subject indicates there is no difference when premium is used in a car that does not require premium.

http://www.edmunds.com/advice/fueleconomy/articles/106293/article.html
http://www.straightdope.com/columns/041008.html
http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm
http://www.usatoday.com/money/autos/2003-07-30-premiumgas_x.htm
http://autos.msn.com/advice/CRArt.aspx?contentid=4024120
http://www.madsci.org/posts/archives/2000-12/976499784.Eg.r.html

I cannot find a SINGLE source that confirms your findings. So, maybe for you this works, but I don't think it's valid in general.

And now your ex is saying not only did she get better milage, but she could 'feel' increased accelerations and performance? Now I REALLY call shenanigans.

Do what you gotta do, my findings have demonstrated an advantage to running premium that satisfies my decision making paradigm.

It is all in the way you quantify the data.
Philip

Okie doke. Simmer down now cowboy, and take note of the smilies in my last post.

Yes Lauren states she "felt" a difference, but power gains aren't verified since we didn't do a dyno run before and after. Notice I never indicated this was a benefit of premium based upon the parameters of the experiment. This was just an additional observation from the person who's car we experimented with.

She is innocent in this, and she is reading the thread so don't be an asshole.

Quote me all the web pages you want, but just because it is on the internet doesn't make it true (as is the case with my own findings)

At least two people in this thread have run a real world comparison and found an advantage to higher octane.

Take it or leave it, I am just the jackass that posted it on the internet. (I am also getting better milage out of my 100k mile+ cars :biggrin: :biggrin: :biggrin: )

If you believe it is eccentric to buy premium for cars that don't require it, than don't.

Philip

 

[H-carWizKid]

The problem with this "real world" test is just that, it was not controlled - rather than sit on a dyno and run through the fuel she ran errands, she drove on the freeway, she drove in traffic, perhaps she was late a day and gave the car a bit more gas than typical - point is, fuel mileage varies between tanks based on driving habits, and the fuel savings you describe is easily within such an error margin - if such a fuel savings existed, on a regular and easily measured basis, everybody would know about it.

I don't see how the octane level would positively impact your fuel mileage - some fuel system cleaner sure, perhaps 'chevron with techron', but just a higher octane? Sounds like somebody has a case of the 'premium' placebo effect.

In my case, I use premium (unfortuantly the highest in SoCal is 91 octane) in the nsx, and I use standard (87 octane) in the Leganza.

No doubt, but I wasn't trying to prove a point to the scientific community at large- I was proving the point to her. You are right her trips did very, so the "control" is muddy, but generally speaking the vehicle in question was driven the same way, by the same person, and to the same places as were the daily routine, and the results were tracked accross several tanks of gas in order to work out the averages.

It isn't like we tracked regular for around town driving, then switched to premium and went on a long distance road trip on the highway.

It isn't like we ran one tank of regular vs one tank of premium

the daily use was consistant, and the findings were consistant. The averages were generated and compared by a skeptic (remember Lauren used to be a die hard 86 octane buyer)

no placebo here- we crunched real numbers to figure out the result, and that result favored the premium.

Do what you want. I'll have the super.

Philip

BTW- read the article that started this debate. Is it not logical to deduce that a higher "knock rate" from the lower octane fuels would lead to less efficient combustion when contrasted to lower knock rate premium fuel?

 

[scorp965]

BTW- read the article that started this debate. Is it not logical to deduce that a higher "knock rate" from the lower octane fuels would lead to less efficient combustion when contrasted to lower knock rate premium fuel?

Philip,

Perhaps you should read the article, did you miss the paragraph where he discusses how knock has limited impact on most modern internal combustion engines?

Most modern cars, however, are designed to employ a specific compression ratio, a measure of how much room is available to the fuel when the piston is at the bottom and the top of the cylinder. This compression ratio--somewhere in the neighborhood of eight to one--tolerates lower octane fuels (such as regular gasoline, good old 87 octane) without knocking. "The compression ratio is fixed by the designer of the engine," Green says. "The regular fuel will burn properly and the premium fuel will burn properly and therefore there is no reason you should pay the extra money." High-performance engines, such as those in some sports cars or older, heavier automobiles, often boast much higher compression ratios. These cars--for example, Shepherd's Subaru WRX--require premium gasoline and will definitely knock without it. "I have to put the 92 octane in," he says. "It has a turbocharger."

Elevation change, traffic conditions, temperature, air conditioning enabled, stereo on, vanity mirror, etc. could have all skewed your 'scientific results'; "generally speaking the vehicle in question was driven the same way" does not instill a great deal of confidence.

 

[H-carWizKid]

Philip,

Perhaps you should read the article, did you miss the paragraph where he discusses how knock has limited impact on most modern internal combustion engines?

Really? Then why do NSX's, and Mr robr's G35 require premium?

Elevation change, traffic conditions, temperature, air conditioning enabled, stereo on, vanity mirror, etc. could have all skewed your 'scientific results'; "generally speaking the vehicle in question was driven the same way" does not instill a great deal of confidence.

here is a thought- try it yourself with your Leganza and report your findings.

Fresh oil change, then 4 tanks of regular, followed by 4 tanks of premium

tabulate results and post.

Not sure how much the dyno time will cost so that you can get the environmental consistancy you seem to require, but hey- I am not making your rules for you.

Our experiment will obviously not satisfy your needs. We were looking at real world results at the time. The results were personally convincing, and I posted them here.

the key phrases here are "average" and "general" since that is how the vehicle is actually driven. I don't know of anyone who's car is used with 100%consistancy on a daily basis, but the varience can be defeated by considering averages rather than specifics.

Our experiment was run over a year ago, and said vehicle has now been relocated here to Chicago. Neither of us drive very much at all anymore since we can both ride the El to work. To repeat the experiment for your gratification is neither neccessary, nor practical.

Lauren and I will toast to your success when you prove we were wrong, (We bet drinks when we were running the experiment) she already got a nice free lunch today since this thread got me thinking about her, I am sure she would also enjoy a free cocktail once you humiliate my argument

I look forward to your findings.


Philip

BTW "Knock" in your internal combustion engine is controlled by retarding the spark- that is why "most modern engines" are able to cope with low octane fuel, "Most modern engines" are fuel injected, and employ "knock sensors" to cope with octane varience. A retarded spark would effect the quality of combustion would it not? Sure the engine will run, but not as efficiently as it would if the spark were not retarded to prevent knock.

To quote Crocodile Dundee: "You can eat it, but it tastes like shit"

 

[scorp965]

Really? Then why do NSX's, and Mr robr's G35 require premium?

It's a higher compression engine, the engine timings have been advanced to the point where they require premium. The ECU can adapt to a lower grade of gasoline, but it will do so at the cost of performance.

With regards to trying every harebrained fuel-economy-improvement theory, without any logical reasoning, why don't you install an intake tornado, complete an oil change, and run 4 tanks of gasoline through the car - tabulate the results, and post. What about magic gasoline particle magnets? An electronic supercharger? A magic gasoline voodoo doll?

 

[H-carWizKid]

It's a higher compression engine, the engine timings have been advanced to the point where they require premium. The ECU can adapt to a lower grade of gasoline, but it will do so at the cost of performance.

With regards to trying every harebrained fuel-economy-improvement theory, without any logical reasoning, why don't you install an intake tornado, complete an oil change, and run 4 tanks of gasoline through the car - tabulate the results, and post. What about magic gasoline particle magnets? An electronic supercharger? A magic gasoline voodoo doll?

Hair brained eh?

Whats the matter?

Chicken?


LoL

Don't be silly- no-one suggested changing anything other than the oil, and your spending habits for a couple of tanks worth of gas. There is no black magic, magic gadget, or anything else. Just curiosity.

I satisfied mine with the experiment we ran on Lauren's 4Runner last year.

I obviously can't satisfy yours, so if you want to discredit me run it yourself. Maybe your Leganza will be just the same no matter what gas you run.

You could even come back in a few weeks, post fake results and lie if it makes you feel better. I don't care.

The results of our test were personally conclusive.

You want to point at web sites and other peoples research, that is fine by me, but I saw what I saw. The 4Runner ran better on premium.

Philip

 

[scorp965]

BTW "Knock" in your internal combustion engine is controlled by retarding the spark- that is why "most modern engines" are able to cope with low octane fuel, "Most modern engines" are fuel injected, and employ "knock sensors" to cope with octane varience. A retarded spark would effect the quality of combustion would it not? Sure the engine will run, but not as efficiently as it would if the spark were not retarded to prevent knock.

The article is using baby steps to describe the impact of different fuel on the mechanical workings of one's engine, perhaps my response to the quote was phrased in a similar fashion; knock itself, as the article mentions, and as common wisdom would dictate, is not good for your engine, knock might affect fuel economy, but, as the article was inferring, modern engines are able to adapt to given ranges of fuel quality, and can burn correctly low octane fuel, as well as 'premium' fuel. If the gasoline is burning correctly, without knock, and the engine compression and timing is such that it operates to full potential on lower octane fuel (such as a Jeep, or Leganza, engine programmed for low octane), what exactly is the benefit of a higher octane fuel? An nsx is designed for higher octane requirements, a daewoo doesn't have the same restriction.

 

[scorp965]

Hair brained eh?

Whats the matter?

Chicken?


LoL

Philip

Yes, harebrained (not hair-brained), in the sense that there is no logical reason for it to work, and your research is deeply flawed - what are the merits of your argument, aside from the legandary promise of better fuel economy?

 

[scorp965]

Hair brained eh?

Whats the matter?

Chicken?


LoL

Don't be silly- no-one suggested changing anything other than the oil, and your spending habits for a couple of tanks worth of gas. There is no black magic, magic gadget, or anything else. Just curiosity.

I satisfied mine with the experiment we ran on Lauren's 4Runner last year.

I obviously can't satisfy yours, so if you want to discredit me run it yourself. Maybe your Leganza will be just the same no matter what gas you run.

You could even come back in a few weeks, post fake results and lie if it makes you feel better. I don't care.

The results of our test were personally conclusive.

You want to point at web sites and other peoples research, that is fine by me, but I saw what I saw. The 4Runner ran better on premium.

Philip

You must love the edit button

 

[H-carWizKid]

Hi Rob,

I've read probably the same stuff as you regarding the benefits/cost of premium and regular gas on cars that only requires regular stuff, but I have to side with Philip on his empirical result.
I've done the same test on my own using my car last year, and Premium did improve MPG quite a bit.
Granted, it was an old car(like the 4x4 used for testing by Philip) whose engine could probably benefit more from premium vs brand new car, but still the improvements were there.

Regards,

I am not alone in my findings either...

Philip

 

[H-carWizKid]

You must love the edit button

I TOTALLY DO!!!

The context of the message doesn't change, just the content.

 

[Vega$ NSX]

Some people may not know this, but the octane rating of gasoline tells you how much gas can be compressed before it spontaneously ignites. Therefore, it does not give you any additional power. If you put a higher octane gasoline in an engine that is designed for a lower octane rating, it will do nothing for you. It will run exactly the same as if a lower octane was put in.

Having said that, if you run a lower octane rating in an engine that requires a higher octane, the engine will do one of two things. It will either ping/knock, in which case prolonged usage will cause engine damage. Or the car will have a ping/knock sensor and readjust itself for the lower octane by adjusting the fuel/air mixture, compression ratio etc. Many newer cars have this feature. At any rate, the car will derate it's performance to keep from pinging/knocking.

So if the car was designed to use a higher octane (say 91) and all you've used is 87, then the car will run fine but at a lower performance level. If you switch to the higher octane then you will notice a performance increase because now you are running at the recommended and optimal engine conditions. If you contine to up the octane and stick 104 octane race fuel, you will no longer notice any performance increases from the 91 octane.

So for say the G35, a relatively new high performance automobile, if you were to go from a 91 octane to an 87 octane, you probably won't damage the engine because it will have a knock sensor built in. However, you will notice a performance loss to compensate for the lower octane and protect itself. It could be postulated that the loss in performance and running at a less than ideal combustion condition would result in lower gas milage. In other words, if a person was used to a certain performance level at 91 octane, they would need to press the pedal harder, and use more fuel, to match the same acceleration performance as they had at 91. This in combination of running harder at a combustion condition less than what the engine was designed for (meaning lower effeciency or effective use of the fuel), could possibly result in using more fuel than at 91. However, this is just a theory and I couldn't begin to prove if this is true or not. I've run a few informal experiments in my MDX, but as others have correctly stated, there are way too many variables to properly conclude a definitive answer without doing this in a more controlled setting.