Quick question about the effects of lower octane gas.

My dad is considering buying an 07' Subaru WRX wagon, which takes premium gas only. What would the neagtive effects be on the engine and the turbocharger system if we were would to put midgrade gas in the tank?

http://www.crankshafted.com/upload/files/19/Mushroom%20Cloud.jpg

Seriously, I don't know the specifics on that car. But I can tell you that it has a knock sensor, which will retard or advance the timing so that predetonation does not occur. In short, using midgrade gasoline, the car will be down a few ponies. Just drive it nicely when using the midgrade gas.

pretty much you'll have less horsepower. I wouldn't recommend putting in 89 octane if you're suppose to have 91, but a few tanks isn't going to hurt it.

if it calls for premium I would go with premium. even if the ecu will automatically retard or advance the ignition to make it work I wouldn't chance ****ing up your engine. predetonation is a bad thing.

I highly not recommand it. My dad filled the BMW with regular when its suppose to be 89, and even with 89 now, the car's acceleration in first gear is really lacking power.

Going along the same lines as above, the car's ability to read the octane and adjust timing is an idiot guard, it is not so that you can choose. It says "PREMIUM ONLY" on the dash for a reason.

If you don't want to fill up with premium, buy another car.

If you don't want to fill up with premium, buy another car.

What he said, end of story, close thread, we're done here.

we recently had a discussion about this subject.......anyone remember which thread it was in?
I remember SteveFX made me bust out laughing, but I am afraid that is all I can remember

Going along the same lines as above, the car's ability to read the octane and adjust timing is an idiot guard, it is not so that you can choose. It says "PREMIUM ONLY" on the dash for a reason.

If you don't want to fill up with premium, buy another car.
/\/\/\ What he said...

Filling up with lower-octane fuel can actually kill your MPG (but not entirely sure about that).....

Here's another you definitely MAY want to consider though. If you fill up with regular, from EMPTY, you really aren't saving a whole ton. Premium gasoline is usually about 30 cents a gallon more expensive than regular, I'll even (for the sake of argument) say it's 50 cents more. The 07 WRX has a 15.9 gallon fuel tank. The difference in price from filling up from empty using premium vs. regular (91 vs. 87) is going to be 50 cents for each of those gallons, or a total of $7.95. At a more realistic number the difference is less than 5 dollars for a FULL TANK of gas.

Let's just say that regular actually DOES get you the same MPG (which it usually doesn't), it is almost proven than your performance WILL go down. You than also have to worry about premature detonation, and the fact that in your owners manual is tells you specifically to use 91 octane fuel. Do you really want to chance destroying your car for 5 dollars a tank?

Seriously, if you want to make that back, try driving a bit slower, or planning out all your routes more carefully so you're on the road less, or recycle some cans, or don't get that extra special coffee in the morning, or don't buy that package of Oreo's, or SOMETHING.

There are many ways we can save money that we just don't do because we don't feel we need to. Well, here is a good reason. Now it's up to you so save that extra 5 dollars! You can do it!

It has a knock sensor, it will be fine, you'll just be down on the hp, but probably not even to a noticeable amount. I run 87 in my VR6 and 91 is recommended and I've put over 50,000 miles on the car with no problems whatsoever.

However, you may find that the car runs rough. My old E36 M3 had to have premium, which is 93 around here. I once filled it up with 87 on accident and it ran so rough I thought it was going to die on me.

So it might vary depending on what car you drive.

What are the octane numbers to choose from in the U.S.? Here they are 95 and 98. I have heard that in the Middle East those numbers are even higher? If so does anyone know what they are?

to make matters more interesting, you don't get 91 octane in the use. its either 87, 89, or 93.

but yeah what evo said, at 20-30 cents the difference between 89 and 93 its not even worth bothering with lower octane fuel.



Argentina had what they called the +99 octane.

Around here it's 87, 89, 91, and at Sunoco, 94. I can't imagine it being much different in the States.

It's not that our gas is any lower in octance, it's just rated/measured differently.

in the us it's typically 87 89 and 91

93 is available in some places and of course if your really determined you can find specialty fuels, such as trick fuel (115 octane I think) but those are stupidly expensive nowadays. back when gas was "only" 3.50 a gallon trick fuel was about 5.50. I can imagine it being 7 dollars a gallon now...

and just wondering, what happens if you do the converse? meaning, what if you should put in 87 or 89 but you put in a higher grade?

would your engine have troubles detonating a higher octance and would it make any difference at all? I'm just wondering cause my jeep runs pretty rough, as described by vr6 man, and I'm wondering if maybe I go a higher octane it'll even out said roughness...

HUSKY FTW. It only offers 90 and 94.


But yes, don't go for a lower grade fuel if it demands premium. It's not worth the servicing after a few years.

in the us it's typically 87 89 and 91

93 is available in some places and of course if your really determined you can find specialty fuels, such as trick fuel (115 octane I think) but those are stupidly expensive nowadays. back when gas was "only" 3.50 a gallon trick fuel was about 5.50. I can imagine it being 7 dollars a gallon now...

and just wondering, what happens if you do the converse? meaning, what if you should put in 87 or 89 but you put in a higher grade?

would your engine have troubles detonating a higher octance and would it make any difference at all? I'm just wondering cause my jeep runs pretty rough, as described by vr6 man, and I'm wondering if maybe I go a higher octane it'll even out said roughness...

I'd say run your tank close to empty and try running 91 or 93, depending on what you get in your state. Its an easy test to see if you just need higher octane gas or if something else is amiss. My E36 had higher compression, so I think that may have had to do with the rough running. Whats your CR?


In PA we get 87, 89, 91, 93, and 94. Not all gas stations in PA have all these, but you always have the choice of 87, 89, and 93. And I know one place that has Turbo Blue, which is 115 octane.

I'd say run your tank close to empty and try running 91 or 93, depending on what you get in your state. Its an easy test to see if you just need higher octane gas or if something else is amiss. My E36 had higher compression, so I think that may have had to do with the rough running. Whats your CR?


In PA we get 87, 89, 91, 93, and 94. Not all gas stations in PA have all these, but you always have the choice of 87, 89, and 93. And I know one place that has Turbo Blue, which is 115 octane.

what you call turbo blue we call trick fuel over here

although it IS blue in call, and typically used on boosted applications, so turbo blue makes sense, lol

from factory my compression ratio is 8.8:1 pretty low, and with 190k miles, I'm guessing the cylinders should have bored themselves enough to lower that slightly.

I know higher octanes are usually used in higher compressioned engines, but I'm curious what'll happen with my jeep, :-k

http://www.restoreusa.com/images/restore-left-1.jpg
Ta da! This could help if you havn't used it yet.

what you call turbo blue we call trick fuel over here

although it IS blue in call, and typically used on boosted applications, so turbo blue makes sense, lol

from factory my compression ratio is 8.8:1 pretty low, and with 190k miles, I'm guessing the cylinders should have bored themselves enough to lower that slightly.

I know higher octanes are usually used in higher compressioned engines, but I'm curious what'll happen with my jeep, :-k

It cant hurt to try. For your sake, I hope it helps it. Otherwise it might be something more expensive.

http://www.restoreusa.com/images/restore-left-1.jpg
Ta da! This could help if you havn't used it yet.

I've been using it for years and I swear by it. it is some AMAZING stuff. makes a huge difference. If I could go door to door trying to sell it i would.

It has a knock sensor, it will be fine, you'll just be down on the hp, but probably not even to a noticeable amount. I run 87 in my VR6 and 91 is recommended and I've put over 50,000 miles on the car with no problems whatsoever.

However, you may find that the car runs rough. My old E36 M3 had to have premium, which is 93 around here. I once filled it up with 87 on accident and it ran so rough I thought it was going to die on me.

So it might vary depending on what car you drive.

I know people who do this. It is counterproductive though. The timing drops to the point where your engine is running well below peak efficiency. This means that it is actually costing you more per mile to operate than if you used the higher grade fuel.
Also you run cooler, so there is more carbon build up on the piston and the valves. Just because you cannot SEE the damage does not mean it is not there

Thanks a lot guys I'll make sure to stay away from the lower grade gas. Its not that we don't want to pay for premium, I was just wondering what the lower grade will do to the engine.

my wife's jaguar vanden plas loses something like 3 or 4 mph if filled with low grade gas

I once filled up a jet ski with the wrong gas. If you've ever been to a dock, you know that there's two types of gas, regular and super premium, and they're both damn expensive. Regular is 87 and the other is 96 I think.

I'm sure you're aware that jet ski engines are fairly high strung. They are small, H.O., and run at a constant high RPM. Well, we filled up our houseboat for the first time on 87, and I happened to fill up the jet ski with the auxiliary hose (draws from the tanks) without thinking. I decided it would be a good idea to put the jet ski in the water while the houseboat was on the lake in some decent chop. It would be hard enough to lower it in the water, and to raise it up would be impossible.

Guess what was now running through my fuel lines? Yup, 87 octane. I hit an incredible top speed of 16 mph and limped it all the way back to the dock, scared that I might lose my motor.

If I were you, I would avoid that experience at all costs.

Here's another you definitely MAY want to consider though. If you fill up with regular, from EMPTY, you really aren't saving a whole ton. Premium gasoline is usually about 30 cents a gallon more expensive than regular, I'll even (for the sake of argument) say it's 50 cents more. The 07 WRX has a 15.9 gallon fuel tank. The difference in price from filling up from empty using premium vs. regular (91 vs. 87) is going to be 50 cents for each of those gallons, or a total of $7.95. At a more realistic number the difference is less than 5 dollars for a FULL TANK of gas.

Let's just say that regular actually DOES get you the same MPG (which it usually doesn't), it is almost proven than your performance WILL go down. You than also have to worry about premature detonation, and the fact that in your owners manual is tells you specifically to use 91 octane fuel. Do you really want to chance destroying your car for 5 dollars a tank?

Seriously, if you want to make that back, try driving a bit slower, or planning out all your routes more carefully so you're on the road less, or recycle some cans, or don't get that extra special coffee in the morning, or don't buy that package of Oreo's, or SOMETHING.

There are many ways we can save money that we just don't do because we don't feel we need to. Well, here is a good reason. Now it's up to you so save that extra 5 dollars! You can do it!

Someone give this man a trophy. It just makes sense. lol

Oh yeah, and at my local 76 station, the different between 87 and 91 is 20 cents. So means you'd only be saving $3.18 if you're car was running on empty when you filled up every time. You know what $3.18 buys you today? Not even ONE gallon of gas.

^^^ 3 chicken sandwiches at Macdonald's dollar menu.

Good discussion, my 01 Ram uses regular but when I fill it with 89 I only see slight increases in performace/mpg so I just stick to the cheap stuff

Check your owners manual. Some cars ECU's are programed to run on premium and regular. I have used regular in my RSX-S and never had any problems. In all honesty, if you are driving a new car and you stay on top of your maintenance, there is going to be no problem using a lower grade gas.

I am currently doing a study with my car to figure out my cost per mile using regular and premium so see if I am actually saving anything. I do have lower power with regular, but I don't know how much its saving me.

If your car takes premium, dont bother jumping down to midgrade, if your going to go lower, go balls to the wall because your ECU is just going to probably drop down to low anyways **thats what I have been told by my mechanic**

You are not going to destroy your engine if you use regular. The mechanics I know swear by it, if you read the news, the auto manufacturers swear buy it, and its in pretty much every news article
about making the switch.

New York Times:

Porsche, for example, acknowledges that any of its modern production cars can be run on regular fuel without the risk of damage.

A spokesman for Porsche North America, Tony Fouladpour, added a caveat. “If you want the car to perform at its maximum capability, the best choice would not be 87,” he said. “But we do not forbid it.”

I took the liberty to get some NYtimes articles that I recently read **I hope you guys can read them, I dont know if you have to sign in and be a subscription holder or a college student to see it**

http://www.nytimes.com/2008/08/03/automobiles/03OCTANE.html?_r=1&ref=automobiles&oref=slogin

http://www.nytimes.com/2008/06/18/us/18shortage.html?scp=8&sq=premium%20gas&st=cse

What are the octane numbers to choose from in the U.S.? Here they are 95 and 98. I have heard that in the Middle East those numbers are even higher? If so does anyone know what they are?
In Australia, regular is 91, with some premium unleaded being 95, and then the normal 98 for BP Ultimate, and 99 for Shell Optimax.

I've heard 100+ is common in some parts of California, is this true?

E85 is ~100 octane, but not all cars can use it. Also I believe some Sunoco stations carry regular 100 octane, but I'm not sure on that.

Quick question about the effects of lower octane gas.

My dad is considering buying an 07' Subaru WRX wagon, which takes premium gas only. What would the neagtive effects be on the engine and the turbocharger system if we were would to put midgrade gas in the tank?

Just use the recommended premium fuel (91+Octane)
You will get factory spec performance (good) instead of retarded timing/spark (bad)

Your motor will luv u for it :smt047


E85 is ~100 octane, but not all cars can use it. Also I believe some Sunoco stations carry regular 100 octane, but I'm not sure on that.

Yes they do...Mmmm, race gas :smt045

Well you guys are forgeting one point, the big difference between plain gas and premium is not just its octanage but the detergents on it that help to clean and avoid carbonization on the fuel injection, spark plugs oil contanination and all this little annoying dirts.
And unless you have an engine with a really high compression rate (or a forced induction) you won`t feel any significant difference on performance; regardless if you`re using plain gas, premium, super gas like the Podium from Petrobras or lead loaded aviation gas. Sot the main advantage of using premium gas would be keeping your engine cleaner.

In Australia, regular is 91, with some premium unleaded being 95, and then the normal 98 for BP Ultimate, and 99 for Shell Optimax.

I've heard 100+ is common in some parts of California, is this true?

As was previously discuss, our 91 is equivalent of American 87, our 95 premium is 91, and our 98 is 93. Fact of the matter; Australia's fuel is crap, which is why I only use 98.

We stopped at a servo in Switzerland that only served 95 and 100. I gave the type R a full tank of the top shelf goods and it made a hell of a difference over the french 95.

Well just as curiosity...
http://i214.photobucket.com/albums/cc246/brlufer/Diversos/tabelagasolinas.jpg
We probably have one of the best road gasolines in the world, and the worsts at the same time. I mean the Podium is just a masterpiece but in many of our gas stations they fill the plain gasoline with solvents in order to have a bigger profit, and off coarse that isn`t just bad for your car but it`s also ilegal and we are trying to solve the problem.

God damn Swedish, you're such a freggin douche bag it amazes me. Anytime, one ANY subject, how do you manage to turn it to, BUT BRAZIL IS BETTER THAN EVERYONE, JUST LETTING YOU KNOW!!!

DUDE, NO ONE CARES! Serious! You know what's awesome in America, we already have an agency that checks to make sure no one is screwing you at the pump, and we have been for years.

Also, if you WANT better gasoline over here, you can get higher than 95.

Well that`s why you got the tittle of angriest member (the angry beaver also doesn`t help you, maybe a platypus or a pelican would be better for your image)... So you could had being a little more polite in your posts. And you must know that I particullary do not care about you so you go to that place (Brazilian stuff don`t ask...), but it`s goos to know your opinion so... I will try to be a little less patriotic, actually we all could be a little less patriotic around here.

Any ways back on topic, I had two intentions with that pic. First: Show that even not being the best country in the world we actually have high end products as good as yours. Second and most important: Wich unit we are using here? Yeah I mean there is three main units for measuring gasoline; different countries uses different units and since so it`s quite hard to compare products from different parts of the world.

I get angry because you are acting like we are CONSTANTLY putting your country down or saying it's crap when you really need to realize that we couldn't give a rats ASS about what Brazil is doing. As a country, I imagine they doing just fine because we don't hear ANYTHING from them. Nothing good, nothing bad. That's a GOOD thing if you really want to know. I have no problem with Brazil at all. You guys make fine sugar gas, ju jit su fighters, and hot chicks. I also have no problem with patrotism as long as it isn't brought up in EVERY DAMN THREAD for no reason at all and often overrides all logic and facts.

Also, this thread was about a question of if it would be ok to fill up with regular/midrange gas if the car recommended premium. You were responding to a tangent question that had already been answered.

As was previously discuss, our 91 is equivalent of American 87, our 95 premium is 91, and our 98 is 93. Fact of the matter; Australia's fuel is crap, which is why I only use 98.

We stopped at a servo in Switzerland that only served 95 and 100. I gave the type R a full tank of the top shelf goods and it made a hell of a difference over the french 95.
Gay. Could that be because America uses AKI often, or is Australia's fuel generally *****ter than Americas?

I get angry because you are acting like we are CONSTANTLY putting your country down or saying it's crap when you really need to realize that we couldn't give a rats ASS about what Brazil is doing. As a country, I imagine they doing just fine because we don't hear ANYTHING from them. Nothing good, nothing bad. That's a GOOD thing if you really want to know. I have no problem with Brazil at all. You guys make fine sugar gas, ju jit su fighters, and hot chicks. I also have no problem with patrotism as long as it isn't brought up in EVERY DAMN THREAD for no reason at all and often overrides all logic and facts.

Also, this thread was about a question of if it would be ok to fill up with regular/midrange gas if the car recommended premium. You were responding to a tangent question that had already been answered.
First: Nice hat, it really reduced your angry factor and pumped up your cute one.
Second: I got it, I will try to reduce my patriotism levels.
Third:I have a question about fuels in the US. Why you have E85 and not E100? I mean a flex fuel engine or a simple ethanol one would work better with pure ethanol rather than a mix with gas.

First: Nice hat, it really reduced your angry factor and pumped up your cute one.
Second: I got it, I will try to reduce my patriotism levels.
Third:I have a question about fuels in the US. Why you have E85 and not E100? I mean a flex fuel engine or a simple ethanol one would work better with pure ethanol rather than a mix with gas.

I do believe E85 already has a rediculously high octane rating. 100% ethanol, I predict, might have an even higher octane rating than E85. You'd have to re-engineer some engines throughly, I think. Someone please correct me.....

Yeah it would be nescessery to do some minor changes but... they are just minor. It`s common place to use e100 even on crap cars like fiat Uno Mile, VW Gol, Fox, Honda Civic, etc... (no performance land guys, here for the price of a C6 you get an Accord, and you won`t see nothing better than Civic in a regular day) And it`s also common place as one of the easiest performance updates around here is to make an engine suitable to run on e100.

I checked E85 has about 105, as good as some racing gasolines around, and E100 amazing 115 octanes. Just as curiosity we actually don`t have true gasoline here, by law gasoline have to contain about 5% of ethanol on it.

I do believe E85 already has a rediculously high octane rating. 100% ethanol, I predict, might have an even higher octane rating than E85. You'd have to re-engineer some engines throughly, I think. Someone please correct me.....

E85 is not actually 85%, it's more around 70-75...
As for the octane, it is around 100 octane...

Depending on composition and source, E85 has an octane rating of 100 - 105 compared to regular gasoline's typical rating of 87 - 93. This allows it to be used in higher compression engines which tend to produce more power per unit of displacement than their gasoline counterparts. Since the reciprocating mass of the engine increases in proportion to the displacement of the engine E85 has a higher potential efficiency for an engine of equal power.

Please for the love of all things great, don't ever cite Crapi-pedia. But I don't doubt what you said.....

Please for the love of all things great, don't ever cite Crapi-pedia. But I don't doubt what you said.....
OMFG STFU n00b! Wikipedia is teh best sourz evar!!!!

JK

I only quoted it because I was looking for a quick explanation, and it was the first result.

*mods, the above sentence IS NOT a flame of AWDFreak.