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Old 04-20-2012, 11:33 AM   #16
330zhp
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Originally Posted by BennyL View Post
So I'm thinking of getting an E46. Haven't decided which one, don't really have a preference for any specific engine.

I'm wondering if it's safe to run any of them on regular gas (87 octane). And if so, what are the effects.

I did a quick search and didn't come up with anything. So, any input ppl?
I just acquired a 2005 330cic zhp from the U.S. I researched alot and found regarding fuel, that what you save at the pump, you likely lose in mileage with lower octane. Higher octane also has more helpful additives for your high performance engine, saving on the cost of issues later on. Heard that Shell was the best in Canada and also heard this from my Harley tech when I owned one. Just had mine a short time but sure do like it so far.
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Old 04-20-2012, 12:18 PM   #17
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There is more to gasoline than just the octane rating. Shell 91 is a premium fuel for many reasons, including excellent lubricity and combustability through the entire engine stroke with excellent cleaners to keep the valves, guides and parts clean, especially in high revving over square motors like BMW.

I would never run that 94 octane/ethanol crap in my car. Shell 91 only.

If the vehicle is factory tuned for 87 then use 87. If its tuned for 91, use 91. If you want to save money, buy a chrysler mini van and run 87.

Ethanol does not belong in any turbo or supercharged application.
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Old 04-20-2012, 12:50 PM   #18
330zhp
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Originally Posted by Dinanstu View Post
There is more to gasoline than just the octane rating. Shell 91 is a premium fuel for many reasons, including excellent lubricity and combustability through the entire engine stroke with excellent cleaners to keep the valves, guides and parts clean, especially in high revving over square motors like BMW.

I would never run that 94 octane/ethanol crap in my car. Shell 91 only.

If the vehicle is factory tuned for 87 then use 87. If its tuned for 91, use 91. If you want to save money, buy a chrysler mini van and run 87.

Ethanol does not belong in any turbo or supercharged application.
I think you're absolutely right... if you don't put the proper recommended octane in it... you shsouldn't be driving it.
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Old 04-20-2012, 02:25 PM   #19
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Ethanol does not belong in any turbo or supercharged application.
IZOD Indy begs to differ.
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Old 04-20-2012, 02:38 PM   #20
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IZOD Indy does not differ at all.
They are promoting ethanol, which is a debatable environentally and political issue.
The engines do not produce the same energy as gasoline would. (actually ethanol has 34% less energy than the same amount of gasoline).
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Old 04-20-2012, 06:12 PM   #21
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My owners' manual says that I can use 87 or 91.... So my assumption is that the impact would only be performance or mileage. Make sense? I haven't tried it yet, but it might be time for a test.
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Old 04-20-2012, 06:29 PM   #22
330zhp
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My owners' manual says that I can use 87 or 91.... So my assumption is that the impact would only be performance or mileage. Make sense? I haven't tried it yet, but it might be time for a test.
It's certainly not in my owners manual that 87 is is recommended. Still, if the assumption is that the impact would "only be performance or mileage" why would you use 87 unless you had to? The cost differnece would be negligable if you lose mileage and if there was even the chance of more mainteneance due to using a lower grade, even small $bill$ would likely eat up any savings at the pump. Speaking for myself, I invested in the BMW for the performance and mine is a bit older (2005) so I'll give it what it's made (and recommended) to have and hope if serves me well for a long time.
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Old 04-20-2012, 06:43 PM   #23
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Originally Posted by 330zhp View Post
It's certainly not in my owners manual that 87 is is recommended. Still, if the assumption is that the impact would "only be performance or mileage" why would you use 87 unless you had to? The cost differnece would be negligable if you lose mileage and if there was even the chance of more mainteneance due to using a lower grade, even small $bill$ would likely eat up any savings at the pump. Speaking for myself, I invested in the BMW for the performance and mine is a bit older (2005) so I'll give it what it's made (and recommended) to have and hope if serves me well for a long time.
I would agree. It's likely not worth it, but it doesn't sound like it's harmful given that the manual says 87 is ok. I think that the sophistication of the fuel management recognizes this and adjusts.

If it comes down to performance and mileage then at least it's a conscious decision. Of course this may also be model and engine specific. Where my 528 says it is fine, this may not hold for other models.
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Old 04-20-2012, 08:06 PM   #24
Dinanstu
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The engines were designed with target fuel requirements and should be generally followed. Using 91 when 87 is the requirement is a waste if money. The comment I made about the minivan is true, I have one and use 87.
Engines designed for 91 will give the best performance balanced with economy but lower grades will adapt and it does say that in the owners manual.
Each of my vehicles are running what is recommended, I dont corners with fuels or oils....Engines are worth it!
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Old 04-21-2012, 06:21 PM   #25
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why are we still talking about his 1 year later? :p
I say, to each their own... whether is knowledge or ignorance! :p
Its tuned for 91, if you use less... its at you own profit or peril...

CLOSE THIS THREAD! :p
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Old 04-21-2012, 08:08 PM   #26
JeffCharger
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why are we still talking about his 1 year later? :p
I say, to each their own... whether is knowledge or ignorance! :p
Its tuned for 91, if you use less... its at you own profit or peril...

CLOSE THIS THREAD! :p
What's tuned for 91? Your car or all? I'm interested in an informed decision, not a biased one. My owners manual says 87 is fine.... So what's the problem with it? Is this an ignorant question?
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Old 04-21-2012, 08:10 PM   #27
330zhp
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why are we still talking about his 1 year later? :p
I say, to each their own... whether is knowledge or ignorance! :p
Its tuned for 91, if you use less... its at you own profit or peril...

CLOSE THIS THREAD! :p
I just joined, so though it's an old thread, I hope part of the purpose of this forum is to participate and exchange views. If not, I guess I missed something.
I have learned from what is said, I hope people will be tolerant of the likes of me. If the thread bores you, I presume we can all tune out that which no longer interests us. Thanks everyone for the exchange.
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Old 04-21-2012, 09:02 PM   #28
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Lol, seems this thread is universal for every car forum..


Use all the 87 you want. You'll just get worse performance and poorer mileage per tank (15% ethanol). It won't damage anything.

With the Canadian price difference between 87 and 91, you'll always pay a bit more (extra mileage per tank considered) but very little more.
I run the EU2 tune on my car so I actually could suffer more from low octane gas, so all she gets is Shell 91. Petro 94 is crap btw.
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Old 04-22-2012, 03:41 AM   #29
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Originally Posted by BennyL View Post
So I'm thinking of getting an E46. Haven't decided which one, don't really have a preference for any specific engine.

I'm wondering if it's safe to run any of them on regular gas (87 octane). And if so, what are the effects.

I did a quick search and didn't come up with anything. So, any input ppl?
Benny,
As far as I know since e36's appeal more to me at this point in my life. The only models of that make are the 4 bangers: 316i,is,ti; 318i,is,ti's that only require 87 by factory standards. I own a 97 318ti and these bad boys are sure fun and great on gas! It holds about 60 liters and gets about 30-33mpg on hard drives as well so If anyone hasn't suggested you a model and class with great fuel econ I'd look into those. If you want something faster and heavier go with the inline 6's and pay the extra for 91. By my knowledge every e46 takes 91 or over so you're poop outta luck my friend. They don't call them big money wasters for nothing
Cheers - Darryl

Last edited by ///Lucid; 04-22-2012 at 03:44 AM.
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Old 04-22-2012, 10:49 AM   #30
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First things first, the term 'premium' is a marketing ploy. It is not better gas than regular, it's different gas. If you want good gas, go to Petro or Shell since they don't use ethanol (yet afaik), and avoid esso, pioneer, sunoco, and essentially all others. There are no more impurities in 87 than there are in 91 so your fuel filter WILL NOT get damaged. Furthermore, the engine isn't tuned to the point where damage will occur if you run anything less than 91, even over an extended period of time. If it did get damaged under these circumstances then there wouldn't be any possibility of tuning the engine any further, or running boost on this engine. Think critically, if you needed to run 91 stock, then how could anyone push 6-8psi on the same gas without damage....answer is they couldn't. Furthermore, the octane rating is actually a ratio of septane and octane (two different types of gas). 87 has as you would imagine 87% octane and 13% septane. Does this really matter, well since septane has more btu's than octane, yes it does because you get WORSE mileage out of an engine if you run higher than needed octane...yes, you did read that correctly. Most people look at a compression ratio and automatically assume that alone defines what type of gas is required, that's an incorrect mentality. Compression ratios are important, but so is the material the block is made of, the material the head is made of, the altitude the car is driven in, the humidity the car is driven in, the air temperature, the rpm range (based on idividual drivers), the load (if the car is towing or full of fat people), the temp of the spark plug, the type of fuel delivery, the list can go on for quite some time I've just listed some for illustration purposes. The reason a company like BMW will put a 91 octane required sticker on the gas cap is to imply exclusiveness, and protect themselves. If they didn't put that sticker there you can be damn sure that some jacka$$ would drive the car through a desert, while towing a camper with the A/C on and farting along at 1200rpm...essentially destroying the engine while the car was under warranty.

From my personal experience, when I'm driving on winter tires, I use 87, when on summer tires, 89. And from what I've read compared to other e46 owners I get much better mileage than average. This is owning 2 non-m e46's ('01 325Ci, and '04 330Ci).

I don't think you understand where the octane number comes from.

Please see the Wiki on Octane Ratings

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

and here is a quote from there that should answer people's questions

"However, burning fuel with a lower octane rating than that for which the engine is designed often results in a reduction of power output and efficiency. Many modern engines are equipped with a knock sensor (a small piezoelectric microphone), which sends a signal to the engine control unit, which in turn retards the ignition timing when detonation is detected. Retarding the ignition timing reduces the tendency of the fuel-air mixture to detonate, but also reduces power output and fuel efficiency."


It is true that running a lower octane rating will not damage your stock engine, but it will be running with retarded timing.
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