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Old 04-09-2014, 10:24 AM   #1
wrdriggs
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Running 87 Octane...

**flame suit on**

Just curious as to who else on here is running 87 octane with good results? My car has 215k on it, been running 87 octane for the past 30k miles, still get 25 mpg, and no real performance issues noticed.

Intake manifold has been off, and no gunk build up on any of the valve, everything looks very clean. I understand these cars are "designed" to run off 91 or better, but IMO, its not a high compression motor, no forced induction, so I don't really see the point. I was a tech for 5 years and still work in the automotive service industry so i have a good idea of how these cars work. Please don't respond if you don't have an intelligent response

Has anybody switched from 87 to 91/93 and noticed a noticeable difference?
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Old 04-09-2014, 10:28 AM   #2
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The lowest grade of gas here in Germany is 95. I think you're playing with fire here.
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Old 04-09-2014, 10:30 AM   #3
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Straight from the BMW spokesperson, we get the final verdict regarding using 89 or 87 octane gas in our 91 preferred cars.


Running On Regular: Do Premium Vehicles Really Need Premium Gasoline?

From Stan Baldwin online

Long before gasoline rocketed through $4 a gallon many people were dismayed to see a significant percentage of their income disappearing into the tank of their car. Today, a wobbly economic outlook, increases in the cost of most other forms of energy, as well as the cost of life’s staples, have prompted folks to look for every possible way to cut back on spending. “Can I save money by running my car on Regular?” “Will it hurt the engine?” my friends ask. More than one person driving a car the manufacturer has spec’d for Premium has told me “I use Regular and my car runs fine.” Are there consequences of “down grading” your fuel? It is definitely a timely question, so we sent e-mail inquiries off to a half dozen manufacturers asking about their technology and their policy on the matter.

While waiting for their reply let’s review some internal combustion engine characteristics. Fuel does not truly explode in a cylinder, at least it isn’t supposed to. It burns smoothly, albeit very rapidly, across the cylinder. The octane rating is a measure of the propensity a given fuel has to burning, rather than exploding. Gasoline “exploding” in the cylinder is frequently called “detonation” or more colloquially, “knocking” or “pinging”. These explosions, because they happen as the piston is rising during the compression stroke and try to shove the piston back down the bore, can do damage over time. In the case of severely stressed motors, such as in race cars, a few seconds of serious detonation can destroy the engine. Two of the mechanical considerations affecting how smoothly a fuel burns are compression and cylinder head configuration. Two variable considerations of great importance are the temperature in the cylinder and the ignition timing. Every manufacturer designs and builds their engines to operate most efficiently for the application intended with a gasoline of a particular octane rating.

Not all that long ago, before the advent of engine management systems, the result of tanking up a high compression vehicle with standard grade fuel was immediately obvious. Providing the stereo wasn’t cranked up past 100 decibels, the pinging or knocking from the engine compartment let you know something was not right. Driving up a hill, towing a load or simply accelerating quickly produced an unnerving rattle from under the hood. It sounded very much like your carbureted V-8 had morphed into a diesel. Until the age of microprocessors enabled the creation of engine management systems, the consequence of a steady diet of low octane fuel could be fatal for a high performance engine.

General Motors, Honda, Toyota and BMW responded to our inquiry. Honda’s public relations representative declined to comment on the issue. Toyota noted that essentially all their current models are designed to run on 87 octane. I asked about using 85 octane, available in some markets, and Bill Kwong of Toyota corporate PR told me they would run fine, with maybe only a slight 2-3 percent decline in horsepower and fuel mileage. But 85 octane is usually only offered in markets at altitude (i.e. Denver, Colorado) where the reduced oxygen doesn’t allow an engine to reach full designed power in any event. If you drive a modern Toyota, the octane rating of your fuel isn’t much of an issue. But what about a brand aimed squarely at the performance market? What about BMW?

Thomas Plucinsky, BMW Product and Technology Communications Manager told us all BMW engines are designed to run on 91 octane. All performance testing, including EPA emissions and fuel mileage, is done with 91 octane. However, though BMW is all about performance, their motors will run on 89 or 87 octane without damage. The knock sensors pull the ignition timing back and eliminate detonation. There will be a loss of power and a decrease in fuel mileage, but the size of the horsepower loss and the increase in fuel consumption depends upon many factors, such as ambient temperature, exact formulation of the fuel and driving technique, so BMW does not offer any estimates for operation on lower grade fuels. One not so obvious concern, Mr. Plucinsky noted, is the type and quality of additives the gasoline companies include in the fuel. Premium gasolines may have better additive packages which are more effective keeping fuel systems (particularly injectors) clean and working efficiently, than those in regular grade fuels or off-brand products. Using lower octane or off-brand fuel could be degrading the fuel system over time, setting you up for a repair bill down the line.

Dave Muscaro, Director of Engine Development/Calibration for GM power trains explained GM has “three flavors” of fuel specification for their offerings: Regular (87 octane) Recommended, Premium (91) Recommended, and Premium Required. Again, we are more concerned with the last two categories where regular could be substituted for the specified Premium. All the engines have a knock sensing ability that retards the spark when detonation occurs. For the premium recommended vehicles the spark advance will be pulled back enough to eliminate the detected knocking. The typical driver will not notice a performance decrease, except under load, and mileage will decline slightly. The engines intended for performance, such as the LS7 or the supercharged small block V-8, are Premium Required powertrains. The customers clearly were not primarily concerned with economy when they chose a performance vehicle and GM optimizes the engine management system to deliver the highest possible power output at all times. To this end the detonation control system does not retard the spark to the point required to prevent all knocking. It would seem a determined deranged drag racer could run Regular in his Corvette and, over time, he might manage to melt a piston or two.

If burning 87 octane in your car, when 91 octane is specified, will not harm the engine, and the performance degradation is not noticeable in typical driving, how much money can you save? The Energy Information Administration, U.S. Government Department of Energy, offers some figures for US gasoline retail prices (these are averages, all areas, all formulations). A year ago Regular was going for $2.982 a gallon and Premium was commanding $3.196 a gallon. The 21.4 cent difference delivered a 6.7 percent saving over Premium. This June 23, 2008, Regular extracted $4.079 from your wallet while Premium sucked up $4.312 for every gallon. The differential (23.3 cents) has grown slightly since 2007 but buying Regular is now only 5.4 percent cheaper than Premium. Since 5 percent is roughly the typical percentage of mileage decrease to be expected with the 87 octane fuel in a 91 octane engine, is there any savings at all?

Bottom Line: Most modern engines are fuel injected and controlled by sophisticated engine management systems which can rapidly and accurately compensate for lower octane fuel by retarding the ignition. Running these cars on 87 octane will not hurt them. However, the immediate savings at the pump may be wiped out by the subsequent drop in fuel mileage and performance, not to mention the possibility of damage over time.





"There will be a loss of power and a decrease in fuel mileage, but the size of the horsepower loss and the increase in fuel consumption depends upon many factors, such as ambient temperature, exact formulation of the fuel and driving technique, so BMW does not offer any estimates for operation on lower grade fuels."

Buried in some promo literature for my BMW R1200RT motorcycle, there is the figure of 101 peak HP when running on reduced octane (87?) fuel. As the normal spec is 110 HP, that would equate to about an 8% power loss compared to premium.

Tom K.
got it from another site but it's from a bmw spokeman
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Old 04-09-2014, 10:43 AM   #4
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omfg.. just pay the extra 1 dollar per tank and get what BMW recommends. Else get a bloody Chevy.
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Old 04-09-2014, 10:45 AM   #5
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Bottom Line: Most modern engines are fuel injected and controlled by sophisticated engine management systems which can rapidly and accurately compensate for lower octane fuel by retarding the ignition. Running these cars on 87 octane will not hurt them. However, the immediate savings at the pump may be wiped out by the subsequent drop in fuel mileage and performance, not to mention the possibility of damage over time.

"There will be a loss of power and a decrease in fuel mileage, but the size of the horsepower loss and the increase in fuel consumption depends upon many factors, such as ambient temperature, exact formulation of the fuel and driving technique, so BMW does not offer any estimates for operation on lower grade fuels."

Buried in some promo literature for my BMW R1200RT motorcycle, there is the figure of 101 peak HP when running on reduced octane (87?) fuel. As the normal spec is 110 HP, that would equate to about an 8% power loss compared to premium.
BMW R1200RT motorcycle has a compression ratio of 12:1. For that reason alone you should never run anything but premium. Even 91 octane is marginal for that compression. 93 is a better fit.

Our beams have 10:1 compression motors which are better suited to mid grade 89. Running higher octane will allow the ignition to be advanced allowing more performance. I use premium sometimes and mid grade occasionally. I am seeing no different between the two. No knocking, loss of performance or mpg. I would not run regular though. Regular is better suited to compression ratios of 9:1 and lower.
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Old 04-09-2014, 11:06 AM   #6
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This topic has been beat to death. The only reason to not run 91 or better is if you are cheap or broke and in either case you're driving the wrong car. Who really cares OP, so you've run cheap gas with no issues. Why don't you go ahead and put cheap oil in it too while you're at it. All you're really saying by starting this thread is that you're cheap. You may as well be a troll too because if you put your (flame suit on) then you knew where this thread would go so thanks for opening up a can of worms.

Mods please close this thread because we all know this is a ridiculous topic.


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Old 04-09-2014, 11:12 AM   #7
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Always used 93 since I bought my car brand new.
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Old 04-09-2014, 11:17 AM   #8
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Old 04-09-2014, 11:27 AM   #9
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The lowest grade of gas here in Germany is 95. I think you're playing with fire here.
That's because Europe and the US use different methods to come up with the octane rating. Europe uses the RON (Research octane number) and the US and several other large countries use the AKI (anti-knock index).

http://en.wikipedia.org/wiki/Octane_rating

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Because of the 8 to 10 point difference noted above, the octane rating shown in Canada and the United States is 4 to 5 points lower than the rating shown elsewhere in the world for the same fuel. This difference is known as the fuel's sensitivity,[4] and is not typically published for those countries that use the Anti-Knock Index labelling system.
See the table in the following section for a comparison.
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Old 04-09-2014, 11:27 AM   #10
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This topic has been beat to death. The only reason to not run 91 or better is if you are cheap or broke and in either case you're driving the wrong car. Who really cares OP, so you've run cheap gas with no issues. Why don't you go ahead and put cheap oil in it too while you're at it. All you're really saying by starting this thread is that you're cheap. You may as well be a troll too because if you put your (flame suit on) then you knew where this thread would go so thanks for opening up a can of worms.
Dude, chill out. The OP is driving a $1000 car. Certainly not a high roller.
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Old 04-09-2014, 11:34 AM   #11
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That's because Europe and the US use different methods to come up with the octane rating. Europe uses the RON (Research octane number) and the US and several other large countries use the AKI (anti-knock index).

http://en.wikipedia.org/wiki/Octane_rating
Interesting. I did not know that. Very cool. I learned something new. Thanks.
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Old 04-09-2014, 11:48 AM   #12
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This topic has been beat to death. The only reason to not run 91 or better is if you are cheap or broke and in either case you're driving the wrong car. Who really cares OP, so you've run cheap gas with no issues. Why don't you go ahead and put cheap oil in it too while you're at it. All you're really saying by starting this thread is that you're cheap. You may as well be a troll too because if you put your (flame suit on) then you knew where this thread would go so thanks for opening up a can of worms.

Mods please close this thread because we all know this is a ridiculous topic.


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You seem like a friendly chap! You know, you don't HAVE to participate in this thread.

I think this is an interesting topic and since I'm such a freakin noob I'm happy to see it discussed.
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Old 04-09-2014, 11:52 AM   #13
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93 octane, why use anything else in a bimmer!
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Old 04-09-2014, 11:58 AM   #14
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OP, I'm with you.

With my 330, I was getting about 27 mpg on 87 octane. Our prices (just going with what I remember the last time I cared) were $3.35 for regular, and 3.75 for premium. So, $0.40 more per gallon for premium.

Percentage-wise, this equates to a cost difference of 11.9% more for premium. To break even on price, I would have needed to see 30.213 mpg. That's just breaking even. I have yet to see anyone averaging more than 30mpg on one of these cars.

But yes, this is a dead horse. The bottom line is that people here will look down on you for using inferior fuel and claim you're getting poorer gas mileage and lower power. Realistically, though, the power loss will not be noticeable, and whether or not the cost increase over potential mpg increase is worth it will be up to your own math.
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Old 04-09-2014, 12:12 PM   #15
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Maybe it's just me, but I do feel a noticeable difference, especially on hot days. On colder days, you can't tell any difference, but on hot days, sitting in traffic with the AC on or even just cruising, there's definetly power loss, not hugely noticeable but it's there.

Not sure if it's worth the difference between premium/regular, but I run 91 only because it's recommended, by the people who designed the thing.
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Old 04-09-2014, 12:37 PM   #16
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The bottom line is that people here will look down on you for using inferior fuel and claim you're getting poorer gas mileage and lower power. Realistically, though, the power loss will not be noticeable, and whether or not the cost increase over potential mpg increase is worth it will be up to your own math.
It has nothing to do with using an "inferior" fuel. Forget regular/midgrade/premium designations. Engines are designed with a certain compression ratio that fit with a certain octane level. The m54 engine was designed for fuel of 91 octane or greater, period.

The same logic applies to why you put 87 octane in a Honda Civic. The engine was designed for it.
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Old 04-09-2014, 12:49 PM   #17
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I have been driving on 87 for 3 years straight.
No problems, average a 8.7L/100km
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Old 04-09-2014, 12:57 PM   #18
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You seem like a friendly chap! You know, you don't HAVE to participate in this thread.



I think this is an interesting topic and since I'm such a freakin noob I'm happy to see it discussed.

Let me at least apologize for coming off like an a$$. However we have this same conversation every couple weeks and it always ends in a huge argument. You could have easily searched and found dozens of these threads to get your answers and you would find that they all get locked in the end. Its just a topic that no one will ever agree on so of course they always get ugly.


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Old 04-09-2014, 12:59 PM   #19
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210k miles and every valve is clean? You sir, are full of sh!t or don't know what you're looking at unless the heads have been redone sometime fairly recent. The octane question has been neaten worse than a dead horse, do what you want, but if you're cheap you're driving the wrong car.
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Old 04-09-2014, 01:04 PM   #20
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Dude, chill out. The OP is driving a $1000 car. Certainly not a high roller.

Its still a car that comes with a stigma of success no matter how old it is. When the general public sees a BMW they automatically think that person has some cash. Unless the thing is just so beat up and rusted out that it looks like its falling apart. Buying a BMW comes with a couple of very simple recommendations to help it run at its best. One is using the proper synthetic oil, and the other is to use at least 91 octane. Its very simple and if OP wants his car to perform at its best then its just smart to follow those two very simple things. It doesn't matter how many miles are on it or how old the car is. It doesn't say in the manual that once the car hits so many miles that its ok to just use 87 octane fuel and cheap oil.


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