homepage Welcome to WebmasterWorld Guest from 54.161.155.142
register, free tools, login, search, pro membership, help, library, announcements, recent posts, open posts,
Become a Pro Member

Home / Forums Index / Local / Foo
Forum Library, Charter, Moderators: incrediBILL & lawman

Foo Forum

    
Car Experts: Does octane level affect gas mileage?
I'm in over my head with this stuff
MatthewHSE




msg:3409131
 2:15 am on Jul 31, 2007 (gmt 0)

A car salesman recently told me that the fuel octane level doesn't have any affect on your gas mileage. He mentioned this because he was trying to sell me a Buick LeSabre (which will run on 87 octane), and what I really want is a Buick Regal GS (which requires premium gas for the supercharger).

The salesman tried to tell me the Regal would cost more to drive because it needs more expensive gas, and I countered with my honest belief that even the LeSabre's fuel economy rating probably counted on using premium gas. He said no, a car made to run on 87 octane gas will get the same mileage with that grade of fuel as it will with 92.

Is that true? Or have I been right all these years to believe that premium, 92 octane gas is worth the extra twenty cents per gallon because of increased mileage?

Very confused with all this...thanks in advance for any thoughts!

Also, any advice regarding the Regal GS versus the LeSabre would be much appreciated, as I'd really like to make my choice and buy a car sometime this week! :)

 

encyclo




msg:3409153
 2:36 am on Jul 31, 2007 (gmt 0)

I'm not a car expert (so I'm happy to be corrected), but my understanding was that higher octane gave you more power, not better gas mileage, and that car engines are set up to operate best with one recommended type of gas: so the LeSabre would run best with 87 and the Regal with 92.

Also, any advice regarding the Regal GS versus the LeSabre would be much appreciated

Aren't Buicks for old people? Can't you just buy a Toyota like everyone else? ;)

MatthewHSE




msg:3409480
 1:16 pm on Jul 31, 2007 (gmt 0)

Aren't Buicks for old people? Can't you just buy a Toyota like everyone else? ;)

Heh, the Regal GS may look conservative, but it packs a punch under that hood! Zero to sixty in six seconds won't make it a sports car, but it's no laggard either!

Anyway, I decided on Buick because I want an American car and Buicks last best. Actually, mile for mile, they're a better value than any of the foreign options I've checked out.

So high octane is for power and doesn't impact fuel economy? In that case, the LeSabre is looking better, although I hate to give up the looks (and the supercharger) of the Regal... ;)

Philosopher




msg:3409512
 1:59 pm on Jul 31, 2007 (gmt 0)

Here's a decent article that should explain it better for you.

[torquecars.com...]

[edited by: lawman at 3:21 am (utc) on Aug. 1, 2007]

jsinger




msg:3409658
 4:10 pm on Jul 31, 2007 (gmt 0)

Higher octane gas requires more more crude to produce. Use only what the manufacturer recommends. You don't gain by filling your tank with a more expensive grade.

Many teens seem to think their Chevette will run like a Corvette if they use more expensive gas.

A real money maker for gas stations, and so wasteful of resources.

encyclo




msg:3411655
 4:50 pm on Aug 2, 2007 (gmt 0)

although I hate to give up the looks (and the supercharger) of the Regal

So tell me, are you itching to buy the fast car and are just looking for reasons to justify the extra expense, or are you genuinely interested in the gas mileage? ;)

I never believe salesmen, so he's probably trying to pass off a different car because he doesn't have the one you want or because his profit margin is fatter on it. Either way, you've got to choose between speedy and sensible. :)

Automan Empire




msg:3411802
 6:20 pm on Aug 2, 2007 (gmt 0)

The quick answer is, it depends, but practically speaking, no.

A high compression engine will benefit from high octane. If it has lower octane fuel and the engine management computer detects detonation or pinging, it retards the timing and richens the fuel mixture, resulting in fractionally less power and efficiency. Most cars do not have high compression engines, though, so there is no tangible benefit to buying premium fuel provided it is a quality brand with a good detergent package. High-octane off-brand gas may be worse than low-octane gas from a top tier supplier. For gentle driving, the difference approaches nil.

Check your owners manual for octane requirements for your particular car. Note that there are different methods of calculating octane. There is a research octane index, a motor octane index, and U.S. gas pumps are labelled with an average of the two (r+m/2 method). Make sure you compare apples to apples.

Premium gas is indeed very profitable for the fuel companies, and they are not going to go out of their way to prevent people from giving their car a "treat" of high-octane even if it does no good.

When you fully understand the hoops engineers jump through to wring every extra 1/100th of a mile-per-gallon out of the vehicles, you become less susceptible to believing in easy solutions to fuel economy. Thank you for not bringing up fuel saver magnets, platinum injection, or the 150-mpg carburetor invented by a guy now on the run from the automakers and oil companies. Every time gas prices spike upward, lots of fuel saving things go on the market, and the running joke in our business is, if you buy one of each, you will have to pull over every 200 miles to bail the gas out of the tank.

I suspect that the fuel savings would not offset the higher cost- that is the practically no part of the short answer.

-Automan

jsinger




msg:3411918
 8:16 pm on Aug 2, 2007 (gmt 0)

Premium gas is indeed very profitable for the fuel companies, and they are not going to go out of their way to prevent people from giving their car a "treat" of high-octane even if it does no good.

Premium gas is largely a racket:

I mostly drive an Infiniti. Premium gas is recommended but manual says cheaper gas will work fine but the mileage will suffer more than offsetting any savings. In such rare situation, expensive gas is sensible.

However we own several cars where premium would just waste money (and crude). Maybe 10% of the time I accidentally fill up those small cars with high cost premium out of habit.
---

I once had a chat with a teenager I saw filling up his compact car with premium. He explained that premium grade gas was filtered better than "regular" grade. (this was brand name gas, btw) Again, not so, according to every article I've read on the subject including several in Consumer Reports.

Why isn't the government educating drivers about the wastefulness of using unnecessarily high octane gas?

MatthewHSE




msg:3412086
 11:11 pm on Aug 2, 2007 (gmt 0)

Thanks for the explanations everyone. Looks like regular ol' gas is the way to go in most cases.

So tell me, are you itching to buy the fast car and are just looking for reasons to justify the extra expense, or are you genuinely interested in the gas mileage? ;)

Hey, who let you in on my innermost thoughts? ;) Actually, I know people who have tested the different fuel grades and swear up and down they get better mileage with premium fuel, which is why (until now) I assumed that was really the case. After what I've read now, however, I'm more inclined to think those folks just happened to get a good tailwind the days they tested premium!

I'm genuinely interested in gas mileage, but given that any vehicle I buy now is likely to be my last stop before a dreaded minivan, I really don't want to give up the fun-factor just yet either.

However, if all I was interested in was a fast car, I wouldn't be looking at Buick sedans in the first place! ;) Really, I believe in driving the speed limit unless there's a good reason (like a tornado in the rearview mirror) to go faster. But the Regal is so responsive and fun to drive compared with what I'm used to that I'm having a very hard time giving up on it!

ken_b




msg:3412110
 12:09 am on Aug 3, 2007 (gmt 0)

[quote[Why isn't the government educating drivers about the wastefulness of using unnecessarily high octane gas? [/quote]

On the other hand, why aren't people educating themselves, and their kids.

Tastatura




msg:3412112
 12:24 am on Aug 3, 2007 (gmt 0)

A high compression engine will benefit from high octane. If it has lower octane fuel and the engine management computer detects detonation or pinging, it retards the timing and richens the fuel mixture, resulting in fractionally less power and efficiency

Automan Emp. has got it right. With modern cars probably biggest influence on gas millage is the way one drives - if you slowly accelerate, rather then just 'jumping on' the silly (gas) pedal you'll get better gas millage....On highway, if you drive speed limit, rather then say 15mph over you'll get better gas millage due to aerodynamics (car has to 'fight' less with air)....

That said in my racecar, and only for track driving, I put highest octane I can (or am allowed by rules) as every itsy-bitsy power gains count ;)

jsinger




msg:3412308
 3:16 am on Aug 3, 2007 (gmt 0)

Remember when Amoco briefly marketed "better looking" gas about 12 years ago?

From FTC.gov: "Amoco Oil Company has agreed to settle Federal Trade Commission charges that its "Crystal Clear Amoco Ultimate" advertising campaign included unsubstantiated claims that Amoco premium gasoline, because it is refined more than competitors' brands and is clear in color, delivers superior engine performance and environmental benefits."

Global Options:
 top home search open messages active posts  
 

Home / Forums Index / Local / Foo
rss feed

All trademarks and copyrights held by respective owners. Member comments are owned by the poster.
Home ¦ Free Tools ¦ Terms of Service ¦ Privacy Policy ¦ Report Problem ¦ About ¦ Library ¦ Newsletter
WebmasterWorld is a Developer Shed Community owned by Jim Boykin.
© Webmaster World 1996-2014 all rights reserved