Premium fuel a benefit?

[Q-ship]

I think premium fuel's extra mileage (from my own experience) is a benefit, because the extra cost is negated by the extra mileage (1.6 exta MPG for me)
and a price difference of .39/gallon. I tried the 87 octane recently, and switched back.
Car runs better on premium than regular (probably criminally high ethanol content 87 octane Pa gas) So you get a better performing car (slightly) at nearly the same cost. (maybe an extra 50c a tank more expensive)

Any one agree? Disagree?

[Seamus]

I definitely agree. When i got my S60, i started it on 87 octane. While it ran fine, i wanted to see what 89 would do. I think i get about 2 mpg better, and it seems to run better. After that we started it in the XC, and it seemed to run smoother with better mpgs. I dont worry about the price difference. 87 octane is 3.87 here, and 89 is 3.97. So thats an extra dollar every 10 gallons. And who can afford to put in 10 gallons at a time anyways. But the extra .10 compensates for the better gasmileage, and you still get better performance. So i agree, 89 is definitely worth it, but i haven't tried 93 octane

[goldxc70]

I have to disagree. When I first got my XC70, MY 04, I tested mpg over hundreds of km and in mixed city and highway driving and I never saw any difference in performance or fuel economy. Save your money now, say I :)

[RockitShip]

MPG may vary depending upon any number of factors; it is safe to assume MPG will be increased with higher octane, although some may see no difference, while others see big improvement. I agree the biggest benefit is keeping things running smoother/cleaner... worth the extra few cents IMHO.

[jda2000]

disagree, regular gas is fine.

Empty the trunk of all the junk you carry there, inflate your tires to 36 psi, be easy on the accelerator and you'll get an even better gas mileage

[Q-ship]

Empty the trunk of all the junk you carry there, inflate your tires to 36 psi, be easy on the accelerator and you'll get an even better gas mileage

It is, they are, I do.

Premium I'm using is 91, lower octane fuel makes the engine retard timing, thus less performace. I just figured it all to be Voo Doo, believing the engines computer can compensate for lower octane. I do not think that is true now.
I'm not saying regular gas is fine, that cheap gas "hurts" your car, or you sould be cained for using it.

I'm saying if you use regular gas because its cheaper, but in actuality its the same because of better mileage then all you are doing is giving up engine performance for the same net $. (albeit not dramatic)

And Ethanol content may be the big factor, because in my opinion Pa 87 octane gas (philly area) must be closer to E20, winter blend is even worse.

All of this was using 87 for around 3 months, My average (2 yr running average) went from 21 to 18.4 (on 87) to 20.0 in the first two weeks of switching back to 91. So that means the increase must have been dramatic to pull a 2 yr average up in 2 weeks.

[sjonnie]

lower octane fuel makes the engine retard timing, thus less performace.
Have you measured that for a fact? Because if the engine is retarding the timing with 87 it means 87 would not be the recommended grade fuel for the engine and the manual would state to use 89 or 93. I see no change in boost with 93 or 87, both go to 8psi without a problem, I haven't measured the timing though.

Interestingly, the car talk guys seem to suggest running 87 in cars that state they need premium and allowing the knock-sensor to control the timing to compensate.

http://www.cartalk.com/content/features/premium/questions.html
http://www.cartalk.com/content/features/premium/myths.html

[Seamus]

Have you measured that for a fact? Because if the engine is retarding the timing with 87 it means 87 would not be the recommended grade fuel for the engine and the manual would state to use 89 or 93. I see no change in boost with 93 or 87, both go to 8psi without a problem, I haven't measured the timing though.

Interestingly, the car talk guys seem to suggest running 87 in cars that state they need premium and allowing the knock-sensor to control the timing to compensate.

http://www.cartalk.com/content/features/premium/questions.html
http://www.cartalk.com/content/features/premium/myths.html


Doesn't the owners manual recommend premium fuel? I thought I read that it recommends it, but doesn't require it. I think the knock sensor will retard the timing before an engine knock, by reducing the timing ultimately cutting performance. Running a higher octane will reduce a knock so the engine won't have to cut power.

[Skater]

I did some calculations to see what kind of mileage increase you would need to pay off the extra price of the premium fuel. I did it for both Canada and the US as the difference between regular and premium prices varies.
Canada first.
On my last long road trip with city driving included, I averaged 9.7L/100km over about 2500km. Price of the regular fuel I used averaged $1.25/L
$1.25/L x 9.7L/100km=$12.125/100km
If I used premium fuel, which is $1.35/L, in order to achieve the same $12.125/100L:
mileage=$12.125/$1.35
=8.98L/100km
So in order to break even on the extra cost of the premium, I would have had to had an increase of about 0.7L/100km. That's not very much, seems very possible.
Now to the US side. Assuming $3.87/g for regular, and 21mpg:
$3.87 x 21 = 81.27miles
Using $3.97 for premium, necessary mileage:
mileage=81.27/$3.97
=20.4mpg
Thats only an increase of 0.6mpg to break even.

In both cases you need a very small increase in mileage to have the premium pay off. To actually measure the increase is hard. Wind, hills, and just how hard you push the accelerator all play into the mileage, and to keep any of those consistent for any length of time would be impossible. You would need to keep track of the mileage over a very long time on each type of fuel to see any thing close to accurate results.

[wgriswold]

I have read recently that some premium gas does not contain ethanol. It seems to me that the lack of lower energy alcohol would lead to increased mileage. I always use 87 and get between 26 and 28 mph with a mix of city and freeway driving.

[Q-ship]

sjonnie

Nope, no idea how to measure when the knock sensor retards timing. But I know that's how it works.

[BIGGUYNE]

Under the Clean Air Act, the US must use at least 15 billion gallons of ethanol this year. Total gas/ethanol consumption will range from 140 to 150 billion gallons, depending on the economy.

In the "old" days, there were 2 grades of gasoline used across the whole country-- regular & premium. As clean air standards started phasing in, different parts of the country used different formulas for regular & premium. Today, there are virtually hundreds of different formulas used...based on location, weather, time of the year, etc.

Wait, in your area of So Cal, ethanol is used in all gas as an oxygenate. And no, it doesn't say so on all pumps.

As for regular vs. premium...if it feels good, then do it! My new XC60 doesn't need premium, but my Audi A6 twin turbo does. The wind & weather conditions on the Great Plains never allow me to get a good mileage comparison.

[jmoser]

Non turbos likely get zero benefit from high octane - the BTU heating value of the premium fuel is actually a bit less per gallon.

My 01XC turbo does seem to break even or better with 91/93 octane - it allows the turbo boost to increase the volumetric efficiency of the engine. I can run 87 octane and the knock sensor will compensate.

I will say that winter fuel costs me 10% in fuel economy :(

My XC loves hot weather - I can get close to 30 mpg at 70 mph on a 90 deg day; lucky to get 26 in February. Average is around 27 [all based on the on board computer feedback.]

Remember that the extra cost per gallon is fairly constant regardless of base price, so paying for premium when gas is $4 per gallon is a lesser % increase than when it was $2.50. The mpg gain I get is constant so at high gas prices premium is a winning proposition.

For around town stop and go I think even the turbo would get the same mpg with 87 octane, you do not get the benefit of the turbo efficiency at lower engine speeds and loads.

[Q-ship]

Looks like no easy agreeable answer.

Oh well, I see a difference, so I'll stick with the premium.

YMMV

I agree, but high compression non turbos need premuim, but others it should make no difference.

[wgriswold]

Wait, in your area of So Cal, ethanol is used in all gas as an oxygenate. And no, it doesn't say so on all pumps.

Actually South Lake Tahoe is in Northern California, an important distinction to those of us in the North.

Here is a website that purports to identify sources of ethanol free gas.

http://pure-gas.org/

I live about 30 miles from Carson City Nevada and the Costco there supposedly has premium ethanol free gas. We often shop at Costco because the gas is about fifty cents a gallon cheaper than in Tahoe. We consistently have the most expensive gas in the country but that is seldom reported because the market is so small. I don't buy the premium and so can't report any possible differences.

[sjonnie]

My 01XC turbo does seem to break even or better with 91/93 octane - it allows the turbo boost to increase the volumetric efficiency of the engine.
Except for the majority of driving the turbo is not providing any boost whatsoever, so that doesn't explain any perceived difference in mpg.

[wiz]

I've always used the Top Tier stations (http://www.toptiergas.com/retailers.html) as most gasoline is sourced from the same refinery in a given region and the only difference is the detergent additives used (or not) by the various brands.

Unfortunately Chevron isn't sold in the eastern US so I've tended to use only Mobil and Shell, but today I filled the car up with Irving gas as apparently BMW think it's good for fuel-injectors (http://www.physicsforums.com/showpost.php?p=2315481&postcount=3), and it is cheap. ;) We'll see.

[Volvos rock]

in the 02 V70XC, I ran 87 for the first couple of years, then switched to 91 or better and saw definate improvement in performance (never bothered to figure out my MPG) but the DIM tells me .5 - 1 MPG gain. The 09 S 80 3.2 calls for 87, I run mid grade, 89 and it runs a ton better. Mid grade is reg/premium mix from what I understand? and at around 1 dollar per fill up differance, I say better.[thumbup]

[KILOFINAL7]

In my previous 2005 XC and my soon to be 2004 XC, I will use 89/91 octane. I got into the habit of keeping the computer display on the instant reading of l/100km and challenged myself to use less fuel in daily driving.

The XC70 was quite economical and having the low end torque really helped on initial acceleration

[goldxc70]

Doesn't the owners manual recommend premium fuel? I thought I read that it recommends it, but doesn't require it. I think the knock sensor will retard the timing before an engine knock, by reducing the timing ultimately cutting performance. Running a higher octane will reduce a knock so the engine won't have to cut power.

The owners manual (for my 2004) says:

Octane rating: Volvo engines are designed for optimum performance on unleaded premium gasoline with an octane rating AKI of 91, or above. AKI (ANTI KNOCK INDEX) is an average of the Research Octane Number, RON, and the Motor Octane Number, MON. (RON + MON/2). The minimum octane requirement is AKI 87 (RON 91).

So optimum performance with 91 or above but anything from 87 up is fine, is how I read that.

[Ars Gladius]

The owners manual (for my 2004) says:

Octane rating: Volvo engines are designed for optimum performance on unleaded premium gasoline with an octane rating AKI of 91, or above. AKI (ANTI KNOCK INDEX) is an average of the Research Octane Number, RON, and the Motor Octane Number, MON. (RON + MON/2). The minimum octane requirement is AKI 87 (RON 91).

So optimum performance with 91 or above but anything from 87 up is fine, is how I read that.

http://www.volvoxc.com/forums/showpost.php?p=128784&postcount=4

[wsp310]

I've found that if I use non-ethanol mixed fuel my mileage increases and shows a net savings in cost per mile. We have 87 octaine with 10% ethanol mix here and in my 2002 suburban I averaged 12.5 mph over the year based on a mix of city/highway driving. It was driving me nuts. I started using non-ethanol blended fuel in either 89 or 91 octaine and found mileage increased a few mpg. From everything I've read, and I'm no scientist, ethanol blended fuels have less energy than non blended fuels. So it's safe to assume that with more energy, less is needed to go same distance. I found that I paid more and the initial cost is daunting ($138.00 at last fill) but when the higher mileage was figured in, my cost per mile decreased between $.03 and $.05 per mile using non blended fuels. I am still able to purchase either 89 or 93 octaine at the same place nearby. Only their 87 is blended at 10%.

I don't buy into the whole ethanol blended sales pitch since it's pushed so hard by those who have created a market for it and some strong lobying on the part of the market.

We have started using non blended fuel on our 2002 XC too with a noticible increase in power and smoothness while starting out. Checking on the mileage still since with the XC we have so many varibles such as how many kids, stuff in the back and what's on the roof. I think there will be an increase but not as dramatic a percentage as I saw with my Suburban. The only real changes in the Suburban was if I had the dog in the back and which way the wind was blowing I guess.

As far as blended fuels, I wish they would have allowed the market to set the standard rather than have it driven by legislation. I don't think it's the same as when we switched from regular to unleaded. Seems that with less energy available to the engine, less mpg, I use more gas and create more exhaust, sending more to the tail pipe. Can't say I've sniffed the back since the change.