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View Full Version : Which Grade of Fuel Do You Use?



Megafast13
Jun 19th, 2010, 10:16 PM
Some say they provide advantages, others say the premium does nothing. Which do you use?

Andy M.
Jun 19th, 2010, 10:22 PM
Regular seems to burn faster than premium in the SS. I stick with 89 octane or above.

Andy

Bill Davidson
Jun 19th, 2010, 10:50 PM
Some say they provide advantages, others say the premium does nothing. Which do you use?

It all depends on your engine's compression ratio. Higher compression engines need higher octane fuel to avoid autoignition. If you are not getting autoignition with the fuel grade you are using, then moving up to a higher octane is simply a waste of money.

It's not as simple as saying higher octane is better or worse. It's more of a question of whether or not it is needed for your engine.

Markus Kleis
Jun 19th, 2010, 11:52 PM
It all depends on your engine's compression ratio. Higher compression engines need higher octane fuel to avoid autoignition. If you are not getting autoignition with the fuel grade you are using, then moving up to a higher octane is simply a waste of money.

It's not as simple as saying higher octane is better or worse. It's more of a question of whether or not it is needed for your engine.

Agreed.

Engines are tuned for a specific octane of fuel - running a higher octane fuel than your engine specifies can even be harmful.

Some engines (newer cars) have intelligent computers which will retard or advance timing based on the fuel provided, allowing the use of E85, 87,, 91 or 93 octane fuels to be used in the same car - BUT - most do not.

Murr1525
Jun 20th, 2010, 01:01 AM
Yeah, best to do what the manual says.

Mine just wants regular, some only want higher.

My dad's car has the variable timing for the grades of gas, but not sure if he has really compared the differences.

J. A. Michaels
Jun 20th, 2010, 02:16 AM
Stick to what the manual states. I burn regular.

Larry A
Jun 20th, 2010, 06:41 AM
I use regular, but I use Top Teir Gasoline , which in my case is Shell.

AndrewR/T
Jun 20th, 2010, 07:06 AM
93 in the truck and 87 in everything else.

Fly Bye
Jun 20th, 2010, 10:09 AM
I use aviation fuel.

Cat
Jun 20th, 2010, 12:06 PM
The Fit doesn't like anything but Regular!

Cat :x

GudniMar
Jun 20th, 2010, 01:48 PM
I use 95 octane, which is the standard in Iceland, I also have the option of using V-Power which is 99 octane.

Bill Davidson
Jun 20th, 2010, 07:17 PM
I use 95 octane, which is the standard in Iceland, I also have the option of using V-Power which is 99 octane.

Iceland sure is an interesting country. Well ahead of it's time.

BTW, my grandparents were born in Iceland. I'd love to visit some day.

Rthario
Jun 20th, 2010, 09:36 PM
Twin Turbo BMW = Top Teir Premium. Shell or Chevron only. :xyxthumbs

Engine de-carb at the dealer is like $500. :dunno

fullbirdmusic
Jun 20th, 2010, 10:57 PM
Since I drive a Porsche Cayenne, I get better gas mileage from the Premium grade stuff. It does have the ping adjustment, but I've tried both Super and Premium and the higher octane goes farther (and faster!).

FRS
Jun 20th, 2010, 11:43 PM
Some say they provide advantages, others say the premium does nothing. Which do you use?


Test for yourself and you'll see.

There s huge difference between 91, 95 and 98 octanes here in Australia.

Recently 10% ethanol was introduced here. A car goes like a **** and spends 25% more petrol.

When I compare 91 and 98 on my bikes, the bike is not puling when using 91 .. huge difference.

:hotrod2

Kornercarver
Jun 21st, 2010, 07:39 AM
I use Premium in my 350Z and Regular in my Dodge Minivan.

tcope1
Jun 21st, 2010, 08:11 AM
First, octane rating is not a power rating... it's a measure of the gasolines ability to avoid autoignition. Running higher octane then needed can actually reduce power.

Second, can't vote as the poll does not include the 85 octane in the Mountain states.

ClearlyCoated
Jun 21st, 2010, 08:21 AM
I use regular, but I use Top Teir Gasoline , which in my case is Shell.The top tier refine all gasoline used in this country in a handful of refineries, then sell their product to smaller distributors. Since refined gasoline is strictly monitored and regulated by the federal government (I forget which agency - something like weights and measures) there is very little variance between gasolines refined by Shell, British Petroleum, Mobil, et al.

Therefore, the gasoline you purchase from 7-11, Valero, or your local convenience store is from Shell, ARCO, or any other major refiner.

tcope1
Jun 21st, 2010, 08:30 AM
Therefore, the gasoline you purchase from 7-11, Valero, or your local convenience store is from Shell, ARCO, or any other major refiner.While not completely correct (additives are what make them different) TTG is really nothing more then a marketing tool. It gives the impression that TTG is better then other gasoline... which is _completely_ unsubstantiated.

Fly Bye
Jun 21st, 2010, 09:27 AM
First, octane rating is not a power rating... it's a measure of the gasolines ability to avoid autoignition. Running higher octane then needed can actually reduce power.

Second, can't vote as the poll does not include the 85 octane in the Mountain states.






repost (http://meguiarsonline.com/forums/showpost.php?p=416727&postcount=3)




:D

Andrew C.
Jun 21st, 2010, 11:31 AM
The top tier refine all gasoline used in this country in a handful of refineries, then sell their product to smaller distributors. Since refined gasoline is strictly monitored and regulated by the federal government (I forget which agency - something like weights and measures) there is very little variance between gasolines refined by Shell, British Petroleum, Mobil, et al.

Therefore, the gasoline you purchase from 7-11, Valero, or your local convenience store is from Shell, ARCO, or any other major refiner.


While not completely correct (additives are what make them different) TTG is really nothing more then a marketing tool. It gives the impression that TTG is better then other gasoline... which is _completely_ unsubstantiated.


Clearly and tcope are right on who you buy gasoline from. My Uncle is the VP of Manufacturing at U.S. Oil and I have asked him about the whole issue of what station you buy your gas from and how chevron has "technron" and all the fancy perks.

He told me the same thing clearly said about it all ultimately coming from the same places and the "additives" that certain stations have don't really distinguish them at all because gasoline already contains those products. I believe technron is some sort of nitrogen additive, which is already in our every-day fuel, and chevron puts it in as overkill and does nothing but serve as a marketing tool.

Take it for what its worth, but why pay more at one station when the one across the street gives you the same fuel for cheaper. :dunno

hacker-pschorr
Jun 22nd, 2010, 07:40 AM
I use aviation fuel.
What kind of car do you drive that runs on variations of kerosene?


Since I drive a Porsche Cayenne, I get better gas mileage from the Premium grade stuff. It does have the ping adjustment, but I've tried both Super and Premium and the higher octane goes farther (and faster!).
I've gone round and round with people about this, especially with boosted (turbo / supercharger) cars.

I'm not picking on you, just using you as an example :D

Just because your vehicle has knock detection that can "adjust" for low octane fuel, doesn't mean it's a good idea to do so. The knock detection goes off after the event, which is not something that's good for your motor. Most engines pull back ignition timing to reduce the knock, some systems are clever enough to also cut back boost, or both. Which lowers overall efficiency (which is why your experienced lower fuel mileage).

People who insist they can run 87 octane in a car that "prefers" high octane because it will "self adjust" are doing damage to their engine.
There is no such thing as "a little knock" to an engine.

The ECU is constantly trying to restore full timing and / or boost, to the point of knock then pulls back again. Over and over and over..... The reason these types of vehicles say in the manual it's OK to run lower octane fuel "in perfect condition (watch the verbiage) is purely sales and a bit of politics. Sales people do not like having to say: "You must run the most expensive fuel on the market with this car" so this gives them an out because technically they are right. But that doesn't make it a good idea, especially for long term use.

The knock detection is there in case of bad / old gas, system hick-up etc... These safety systems were never designed with the intention of allowing you to run lower octane gas. If this was the intent of the designers, they would have a selector switch. Something Porsche did with the 928 back in 1985, there is a "low octane" connection down in the fuse panel. I cannot say I've seen any other cars with this kind of feature.

Bill Davidson
Jun 22nd, 2010, 09:05 AM
OK to run lower octane fuel "in perfect condition (watch the verbiage) is purely sales and a bit of politics. Sales people do not like having to say: "You must run the most expensive fuel on the market with this car" so this gives them an out because technically they are right. But that doesn't make it a good idea, especially for long term use.

We've all probably seen the movie Super Size Me. We've seen that you can run on McDonald's food for a month, but look at the results.

akimel
Jun 22nd, 2010, 09:50 AM
My understanding is that top tier gasoline (http://www.toptiergas.com/index.html) has more detergent additives than the gas one buys at the local convenience store. Is that inaccurate?

Anyway, I use hi-test in my S2000 and I usually buy my gas at the Kroger gas station. Once a year I pour a can of fuel system cleaner into the tank. Heck if I know if my engine needs the treatment or not.

SSMUFF
Jun 22nd, 2010, 12:21 PM
use good old regular in both of my cars. Usually when I change the oil I will buy some mystery oil an add it to the fuel.

Fly Bye
Jun 22nd, 2010, 04:51 PM
What kind of car do you drive that runs on variations of kerosene?





My car flies :coolgleam



:hotrod2

roushstage2
Jul 31st, 2010, 11:48 PM
I have to use a min. 91 octane in my Mustang. I'm "supposed" to be using 93, but I only run Chevron or 76 so I've never had a problem.

Everything else gets 87 octane from wherever is nearby when I need it.

FinalTouchDetail
Aug 1st, 2010, 07:38 AM
My vette would detonate like crazy if I ran under 93. It's tuned pretty aggressively.

FWIW, I haven't run anything other than 93 in any car I've ever owned, lol. They've all been high horsepower cars running lots of timing.

Larry A
Aug 15th, 2010, 07:39 AM
If all gasoline is the same then why do I get 18.5 mpg on Mobil gas , 18.0 on Shell gas and 17.0 on BP. This is all stop and go city driving. I check my mileage after every fill up, and this testing took 4 months.

Ravi_1992
Aug 15th, 2010, 07:47 AM
I used 87 for awhile but my car says use 91 octane on the fuel door so thats what ive been using lately , Ive noticed a significant power increase but I don't know weather I get more milege or not

Ravi_1992
Aug 15th, 2010, 07:48 AM
what are the other benefits of using a better fuel?

tcope1
Aug 15th, 2010, 08:40 AM
If all gasoline is the same then why do I get 18.5 mpg on Mobil gas , 18.0 on Shell gas and 17.0 on BP. This is all stop and go city driving. I check my mileage after every fill up, and this testing took 4 months.There is really no difference in .5mpg... even if you filled up 50 times, it could still vary this much. Driving habits and temperature could account for this. The other difference I can think if is the amount of ethanol that station uses. If less, then your mpg is going to go up. But these stations usually charge a higher amount to compensate.

Bottom line, 1mpg is not a significant amount.

roushstage2
Aug 15th, 2010, 12:16 PM
I used 87 for awhile but my car says use 91 octane on the fuel door so thats what ive been using lately , Ive noticed a significant power increase but I don't know weather I get more milege or not

Between these two links, you should have a pretty good understanding of octane ratings. That being said, using say 91 octane in a car that can use 87 is essentially throwing money away as the car will run with the less expensive gas. If you car needs 91, use it. The newer Dodge Hemi engines require mid-grade (89) IIRC.

http://auto.howstuffworks.com/fuel-efficiency/fuel-consumption/question90.htm

http://www.associatedcontent.com/article/296800/what_does_gasoline_octane_rating_really.html

Fly Bye
Aug 15th, 2010, 02:32 PM
Bottom line, 1 mpg is not a significant amount.





1 mpg is 5.5 percent of 18 mpg. 5.5 percent of 1,000 miles (aproximately 3 fill up's) is 55 miles. 55 divided by 18 equals 3.0 (gallons)


That's about 10 dollars :D

sdprius858
Aug 15th, 2010, 04:40 PM
My Eclipse requires Premium, 91+ so thats what it gets and usually returns 20-24mpg mixed.

The 2010 Ram with the 4.7 flex fuel usually gets 87 and returns 15mpg mostly city, occasionally we'll take it down to the old Pearson Ford in El Cajon Blvd. and 15 and put E85 in it which returns 14mpg but only costs $2.39 a gallon.

The G35 coupe also gets 91+.

The Camry gets 87 and runs fine.

Tuck91
Aug 15th, 2010, 04:56 PM
One of my clients is kind enough to give me free fuel out of his junkyard cars.

http://meguiarsonline.com/forums/photopost/data/500/medium/DSC05153.JPG (http://meguiarsonline.com/forums/photopost/showphoto.php/photo/40520/size/big/cat/500)

cnfowler
Aug 16th, 2010, 04:09 PM
Since you don't have 85 listed, I chose 87. However, here in Colorado we don't have 93. Our premium is 91. Our regular is 85. Its because of the altitude.


Colin

STG
Oct 31st, 2010, 04:43 PM
My car was tuned in California on 91 octane. I now live in Wyoming at 5,100 feet and can use 89 octane with absolutely no problem.

Octane requirement decreases as altitude increases. From Conoco Phillips:

Why are octane ratings lower at high altitude areas?

Lower octane number is required for carbureted engines at high altitudes because the lower air density results in lower combustion pressures and temperatures, the fuel/air ratio becomes richer due to the lower air density, and the spark advance is less due to lower manifold vacuum.

Knock sensors and altitude compensators in fuel-injected engines have lowered the octane requirement reduction at increasing altitude. Studies show an average altitude difference of 0.2 and 0.5 (R+M)/2 per 1000 ft (300 m). Consumers may experience slight power and acceleration reductions.

Practically speaking no new car sold in the United States requires more than 91 octane as states with large populations like California have added so much anti-emissions **** to gasoline that 91 octane is the highest available even near sea level in Los Angeles and San Francisco.

MAYBE you car's ECU can boost performance on 93 octane, but do not assume this. My 2004 Mach 1 cannot take advantage of higher octane unless I have it custom tuned. I know because I spoke with the Ford Calibration Engineer who wrote the programming for the 2003-2004 Mach 1 and the 2001 Bullitt Mustangs.

I've noticed the international posters on this thread. Please note octane is calculated more than one way. The USA uses AKI (Anti Knock Index), Europe uses RON (Reasearch Octane Number). The same fuel's octane is about 4-5 points higher using RON.


I can't believe **** was edited out of my post. Should I carp about **** being censored? After all, carp has the same four letters as ****!

new2detailing
Nov 18th, 2010, 04:01 PM
I use 87 octane for all my vehicles. It is pointless to use a higher grade unless the owner's manual suggests it. Remember, the ECU will help determine the proper fuel/air ratio and adjust accordingly. Unless, one plans on remapping the ECU, it is a fruitless exercise to step up on Octane ratings. Even cars listed for 91 or above octane can run on lower octane in a pinch. The ECU will simply adjust for the lower octane(the car will lose a touch of power to compensate) to avoid premature combustion.

The same methodology applies to when someone adds an intake and exhaust to a vehicle but doesn't pay to remap the ECU. The gains are modest without the remapping. If you want the sound fine, but for performance it is imperative to unlock the potential in the ECU.

As an earlier poster stated, if you go up in elevation, lower octane fuels will assist in decreased oxygen levels. The ECU will automatically adjust for the altitude.

smack
Nov 18th, 2010, 09:32 PM
I use what the manufacturer recomends. In my case its 91. I use chevron.

ANeat
Dec 19th, 2010, 06:37 PM
I use diesel in my car ;)

e85 bish
Feb 8th, 2011, 10:37 AM
i use e85 on my evo
Pros-higher octane rating(105) by switching form 91 to e85 my car gained 95hp and 105torque
Cons-it lower my mpg's so now i have to stop more @ the pump

rcktpwrd
Feb 8th, 2011, 11:49 AM
depends on the vehicle... the regular driver only gets 87 as that is what the manufacturer recommends and anything above that is wasted money. The high performance vehicles get 93 as that is what is needed for the higher compression engines in them.

Shootist
Mar 1st, 2011, 10:17 AM
Only use regular these days, but will occasionally put a tank of Shell Premium in the Infiniti. I can't tell a difference unless I put my foot to the floor and even that may be in my head. The Infiniti says "Premium Only' everywhere...hogwash. I don't think I'm allowed to post links yet, so here's a quote from a 2003 USA Today article, 'Why use premium gas when regular will do?":

All Porsche engines are designed for premium, too, but it's not available everywhere. "Our cars must be able to drive all over the world, and so we are able to run on regular," says Jakob Neusser, director of powertrain development at Porsche's research and development center in Weissach, Germany. "You don't have to feel that a mechanical problem or anything else will happen" using regular gas, even in the highest-performance, regular-production Porsches.

I do use Top-Tier fuels exclusively unless I'm in the boonies with none available. If you're unfamiliar with that, go to toptiergas.com. Of course, old muscle-cars or cars w/o knock sensors which retard the engine timing may very well require a higher octane fuel. I've been told by engineers, however, that a slight ping when under load means the engine is operating at peak efficiency.

Zeta Detail
Mar 1st, 2011, 12:33 PM
Diesel in my case, I regret not seeing it listed. I ride a US-built Jeep, by the way.

In Europe premium is 98 octane and regular 95. I'm surprised to see that in the U.S. 87 octane gas is still sold, but I've heard that the composition of car gasoline varies widely depending on the country.

Joe Dragon
Mar 23rd, 2011, 06:21 PM
I use regular octane in my Avalon because that's what Toyota recommends. The only thing is in the winter I have to use ethanol infused gas (by government decree here in the People's Republic of Colorado), but starting in April I'm back to buying non-ethanol, despite it being 25 cents more; it pays for itself in significantly better gas mileage compared to E85.

panicdog
Apr 6th, 2011, 02:14 PM
It all depends on your engine's compression ratio. Higher compression engines need higher octane fuel to avoid autoignition. If you are not getting autoignition with the fuel grade you are using, then moving up to a higher octane is simply a waste of money.

It's not as simple as saying higher octane is better or worse. It's more of a question of whether or not it is needed for your engine.

:bigups

I follow my car's manual. I work in Saudi Arabia and we only have 2 ratings for gasoline which is the 91 and 95.

I use the 91 because my jeep's manual says so, plus 91 is dirt cheap here at 0.12 usd/liter (cheaper than water). :doublethumbsup2

aris
Apr 6th, 2011, 06:48 PM
87 octane

Farmer
Apr 6th, 2011, 07:06 PM
Nothing less than 91.

jezz12
Sep 20th, 2011, 06:40 AM
in my country cheapest octane is 95...
i pump non other than exxon mobil as it comes with addictive...

beamer
Sep 20th, 2011, 08:42 AM
both my vehicles take premium. i use 91 with no ethanol and just foind a station that has 93 no ethanol. it helped milage alot. ethanol kills milage. i hate the stuff. and if we get worse milage on corn and burn through more whats the point.

Wilhelm
Sep 22nd, 2011, 03:55 PM
Only use regular these days, but will occasionally put a tank of Shell Premium in the Infiniti. I can't tell a difference unless I put my foot to the floor and even that may be in my head.


You may or may not be able to tell the difference, but there is definitely a difference. And the occasional tank of premium isn't going to resolve the reduction in power and may therefore just be a waste of money.

The higher the octane rating, the less chance of know (detonation). As a general rule, for the purposes of discussing whether it is "OK" to use regular gas when the manufacturer recommends premium, detonation is more likely to occur in high compression engine, on a high ambient temperature (like a 100 degree day), and load (e.g., sudden acceleration, carrying a heavy load of passengers/luggage, going uphill.


When a manufacturer recommends regular in a particular model, using premium won't hurt anything, but it is a waste of money. If all you need is regular to run at designed efficiency, anything more contributes nothing to engine performance.


When a manufacturer recommends premium in a particular model, it can and will run with regular. In this situation, if you put in regular gas, the car will continue to run normally and I doubt anyone will be able to tell the difference. However, once you start pressing down on the accelerator, the knock sensor will signal the PCM that detonation is occuring and ignition timing will be retarded until the knocking stops. As a result of the timing retardation, engine torque is reduced. Again, the difference will probably not even be noticed, but it probably affect fuel economy.


The process of retardation of the ignition timing because of the detection of detonation by knock sensor is an adaptation, i.e., the PCM will "learn" that regular is being used and keep the ignition timing retarded to avoid detonation.


The adaptation can be cleared or reset if you have a scanner (not an OBDII scanner/code reader, but a "real" one, i.e., similar in scope and function to one a dealership service department is likely to use. Most people do not have a means of quickly resetting the adaptation, and rely on the car computer to reset the ignition timing on its own. Thus if you start using premium gasoline, the PCM will gradually permit the ignition timing to advance. It may take several tanks of premium to restore normal timing, to regain optimum fuel efficiency.


So if you use regular when the manufacturer recommends premium, the timing will retard, available torque will decrease and merely running the occaisional tank of premium will pretty much have no affect in restoring engine power and fuel efficiency. Real world example: Suppose I have late model BMW, 10.7:1 compression ratio, manufacture recommends premium fuel and I drive around on regular. Within a short while the engine (specifically the ignition timing) will adapt. I will probably only notice when merging onto a freeway or pressing down on the accelerator to change lanes. The same amount of power won't be there. I'll have to give it more gas (which will lower the mpg's). Why run a powerful engine if the full power is there when you ask for it? If the manufacture calls for premium, you're not getting the performance you paid for if you use regular. So even though I can use regular I always use premium so the power to be there when I need it, even if not every day.

Bjkearns
Sep 23rd, 2011, 06:11 PM
91 octane Chevron