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SilverE39
11-08-2004, 11:41 AM
My wife drove the E39 for the 4th time this year...........she normally drives her 4Runner, now sold, and now drives an '05 Odyssey. Anyways, she had to get gas for the E39 on Friday and it's her first time filling up. She puts in 89 Octane :mad: :mad: :mad:

Well, today I drove for the first time since she filled up the tank. And guess what? The E39 sure feels pretty sluggish. Is this what happens when you put lower octane than premium? God, I have another 350 miles to burn b4 I fill it back up w/premium.

Lanc3r
11-08-2004, 11:52 AM
If you truly are having probs with the fuel, You can put some octane booster in your tank. Should help.

Wengenstein
11-08-2004, 12:14 PM
I'd probably just siphon it and save it for my lawn mower :)

Patrick
11-08-2004, 12:23 PM
Your owner's manual probably covers the use of non-premium fuel. Mine does at least, and explains that short term use of such lower grade fuel will not damage your engine.

I always use 98E here, but on one road trip through Estonia, Latvia and Lithuania, I had to use their 93E (do to poor planning and trying to stretch it on one tank). I bought 40 liters of the crappier gasoline, and then when I found a Shell station, filled it up to the fuel door with 98E. After another 250km, I did the same.

To be honest, I really did not notice any problems, or sluggishness.

Anyway, I am sure that you will survive!


.

Patrick
11-08-2004, 12:23 PM
BTW, I also put 98E in my lawn mower ... :eek: :tsk:


.

craigt-from-atl
11-09-2004, 09:41 AM
BTW, I also put 98E in my lawn mower ... :eek: :tsk:


.

Is the "98E" equivalent to the US' octane ratings? ie. is that 98 octane??

Lanc3r
11-09-2004, 09:48 AM
Is the "98E" equivalent to the US' octane ratings? ie. is that 98 octane??

Its closer to our "91" octane

Patrick
11-09-2004, 10:25 AM
http://www.bimmerfest.com/forums/attachment.php?attachmentid=39763


.

subterFUSE
11-09-2004, 06:46 PM
There is a gas station near my house that sells 100+ octane race fuel. How will this improve/hurt the performance of my new 2005 545i SMG?

marinakorp
11-15-2004, 12:39 PM
There is a gas station near my house that sells 100+ octane race fuel. How will this improve/hurt the performance of my new 2005 545i SMG?
depends...

if it is leaded... gonna mess yourcar BIG TIME

besides... the car is not tuned for that... so probably going to be a waste of the $$$ ... anything over the stated rating is a "waste" to some extent, as the car does not make power (any much more useable power) that it is tuned for

some aftermarket tuners, tune for a specific ratung (93, 94, 100... whatever) as the minimum rating, and can get SOME HP gains by tuning for that specific fuel... if the car is tuned fro 91... 94 will not make any more HP for the 93 (much anyway) and the 100 should not make much of a differene to power...

going down in the octane rating, however, does make a difference, as car has knock sensors and will adjust for the lower octane


.02

redbeemer
03-12-2005, 03:45 PM
Remember there is no ocdtane in gasoline. The number is just a measure of how bad the gasoline burns. The higher the octane the worse the gasoline burns. If your bimmer runs without knocking on 89 aki then use that forever. It wont hurt anything by using the better lower octane gasoline if the engine doesnt ping. If it does ping then you can retard the timeing until it doesnt ping. That is what I have been doing for three years now and mine is running fine. The piezolectirc antikniock sensors on the top of the engine retard the timeing all by themselves so there is not need for me to retard timing. I get to use the best quality gas which is the lowest octane my bimmer can burn without pinging. That is optimal efficiency.

MMME30W
03-12-2005, 05:14 PM
Remember there is no ocdtane in gasoline. The number is just a measure of how bad the gasoline burns. The higher the octane the worse the gasoline burns. If your bimmer runs without knocking on 89 aki then use that forever. It wont hurt anything by using the better lower octane gasoline if the engine doesnt ping. If it does ping then you can retard the timeing until it doesnt ping. That is what I have been doing for three years now and mine is running fine. The piezolectirc antikniock sensors on the top of the engine retard the timeing all by themselves so there is not need for me to retard timing. I get to use the best quality gas which is the lowest octane my bimmer can burn without pinging. That is optimal efficiency.

Sorry, I fundamentally disagree. Why would you want to spend a large amount of money for a fine sporting sedan, only to put cheap gas in? This makes no sense to me.

The manufacturer states to use premium gasoline.

Here's a previous post with some links of interest:

http://www.bimmerfest.com/forums/showpost.php?p=1058260&postcount=4

Of course, its your car, you can do what you like. ;)

redbeemer
03-12-2005, 05:37 PM
Do you dispute the lower octane rating better gasoline scientificallly is faster burning higher btu fuel or are you just disputing the fact that the higher octane rating is what bmw says to use in the 525i?

MMME30W
03-12-2005, 05:45 PM
Do you dispute the lower octane rating better gasoline scientificallly is faster burning higher btu fuel or are you just disputing the fact that the higher octane rating is what bmw says to use in the 525i?

:confused:

Neither?

1) I am not a ChemE. Maybe you are? I would like you to post a link to a factual source backing up your assertion to improve my knowledge, however, so that I can learn more about this.

2) Does BMW not recommend to use premium fuel for your car? That seems surprising to me. Certainly my owner's manual states "The engine uses lead-free gasoline only. Required fuel: Premium Unleaded Gasoline, Min. 91 AKI."

redbeemer
03-12-2005, 05:56 PM
BMW uses the term "Premium Unleaded Gasoline" with the knowledge that state laws
vary with regard to the octane that can be advertised as "premium". 89 probably
represents the lowest end of the range of fuel commonly advertised as premium in
the U.S., so any fuel labeled premium will meet the minimum specification. To
answer the original question, no, 89 octane won't hurt his car, and yes, he's
wasting money buying 92. The only time higher octane is of any benefit is if the
car pings on the recommended grade, the timing is advanced, compression is higher
than stock, or the car has forced induction. Pinging occurs when the spark
occurs too early in the cycle. If the fuel/air charge is not compressed enough
(i.e. harder to light) the charge explodes rather than burning at a controlled
rate. The two means of eliminating this condition are to a) use higher octane
fuel which is more resistant to ignition and burns slower and cooler (roughly 1
degree per point of octane) or b) retarding the ignition timing. This is exactly
what happens when the knock sensor detects pinging. In response, the computer
pulls out timing to prevent the pinging. What he means by "overkilling" is that
92 is overkill for his engine, i.e. more than is needed. It won't hurt it, but
it doesn't do any good either. If it makes you feel better to put premium in
your car, knock yourself out (yes, pun intended!)

http://member.rivernet.com.au/btaylor/BMWText/technical/PingingAndHiOctane.html

redbeemer
03-12-2005, 06:10 PM
I would like you to post a link to a factual source backing up your assertion

Fuel basics http://www.eric-gorr.com/techarticles/Fuel_Basics.htm
"You want to lower the octane requirement of the engine as much as possible without lowering engine performance. You also want to use a fuel with an octane rating just high enough to keep your engine from ever detonating."

BMW cars http://member.rivernet.com.au/btaylor/BMWText/technical/PingingAndHiOctane.html
" The higher the octane the less energy in the fuel, lower octane fuel burns more
explosively and quickly."

http://extremegarage.com/techtips/octanefaq.htm
" higher octane wont make your vehicle perform better, go faster, get better mileage or run cleaner. there is no advantage to using a very high octane quality product if you do not need it."

tons more if you need it.

If the BMW engine is working properly and does not knock on the fuel you are currently using then using higher octane fuel will not (can not possibly) provide better performance or economy.

BMW marketing just says that to make you FEEL like you are getting better performance. Its all a marketing trick. Like that golf bag sticker in the boot.

sph17
03-12-2005, 06:31 PM
Fuel basics http://www.eric-gorr.com/techarticles/Fuel_Basics.htm
"You want to lower the octane requirement of the engine as much as possible without lowering engine performance. You also want to use a fuel with an octane rating just high enough to keep your engine from ever detonating."

BMW cars http://member.rivernet.com.au/btaylor/BMWText/technical/PingingAndHiOctane.html
" The higher the octane the less energy in the fuel, lower octane fuel burns more
explosively and quickly."

http://extremegarage.com/techtips/octanefaq.htm
" higher octane wont make your vehicle perform better, go faster, get better mileage or run cleaner. there is no advantage to using a very high octane quality product if you do not need it."
.
I am missing something here?

You are taking isolated quotes to justify your position. The first link is talking about racing fuel in racing cars. The third link actually states that people should follow the manufactures reccomendation, and if the manufacturer said to use regular:

" higher octane wont make your vehicle perform better, go faster, get better mileage or run cleaner. there is no advantage to using a very high octane quality product if you do not need it."

The first and third link do not state that if your car's manufacturer said to use premium, using regular is OK.

The first and third link at least have refrances. The second link is only someones opinion.

You are misrepresenting what the first and third links were saying.

Reading these links does not strenthen your position, they actually argue against your position.

MMME30W
03-12-2005, 06:50 PM
Fuel basics http://www.eric-gorr.com/techarticles/Fuel_Basics.htm
"You want to lower the octane requirement of the engine as much as possible without lowering engine performance. You also want to use a fuel with an octane rating just high enough to keep your engine from ever detonating."

BMW cars http://member.rivernet.com.au/btaylor/BMWText/technical/PingingAndHiOctane.html
" The higher the octane the less energy in the fuel, lower octane fuel burns more
explosively and quickly."

http://extremegarage.com/techtips/octanefaq.htm
" higher octane wont make your vehicle perform better, go faster, get better mileage or run cleaner. there is no advantage to using a very high octane quality product if you do not need it."

tons more if you need it.

If the BMW engine is working properly and does not knock on the fuel you are currently using then using higher octane fuel will not (can not possibly) provide better performance or economy.

BMW marketing just says that to make you FEEL like you are getting better performance. Its all a marketing trick. Like that golf bag sticker in the boot.

Thanks for the links, I appreciate your taking the time to do that.

I am not convinced and we will have to agree to disagree. :thumbup:

I'm not getting the relavance to the first link; how does it support your point?

The second link is from an internet message board, and contains a remark from a Mr. Remy Lutz. I don't know who Renny Lutz is, but my opinion is as valid as his. :)

Your third link contains this quote in full:

"In fact, in most cases, using a higher-octane gasoline than your owner?s manual recommends offers absolutely no benefit. It won?t make your vehicle perform better, go faster, get better mileage or run cleaner. Your best bet is to follow your owner?s manual. "

So, since my owner's manual recommends Premium gas, and I believe I get more performance out of my performance car using Premium, it works for me. :)

PS Welcome to the fest!

FireWalker
03-12-2005, 10:12 PM
Remember there is no ocdtane in gasoline. The number is just a measure of how bad the gasoline burns. The higher the octane the worse the gasoline burns. If your bimmer runs without knocking on 89 aki then use that forever. It wont hurt anything by using the better lower octane gasoline if the engine doesnt ping. If it does ping then you can retard the timeing until it doesnt ping. That is what I have been doing for three years now and mine is running fine. The piezolectirc antikniock sensors on the top of the engine retard the timeing all by themselves so there is not need for me to retard timing. I get to use the best quality gas which is the lowest octane my bimmer can burn without pinging. That is optimal efficiency.What a pile of :bs:.
Just shows you how "a little knowledge is a dangerous thing".

FenPhen
03-13-2005, 01:27 AM
Remember there is no ocdtane in gasoline. The number is just a measure of how bad the gasoline burns. The higher the octane the worse the gasoline burns.I'm no ChemE, but I throw the :bs: flag at you.

The octane rating is not a measure of how "badly" gasoline burns.
http://auto.howstuffworks.com/question90.htm
http://www.elmhurst.edu/~chm/vchembook/514gasoline.html

Gasoline is composed of a bunch of different hydrocarbons, such as heptane (7 chained carbons) and octane (8 chained carbons). Octane burns and handles compression well. Heptane explodes and does not handle compression well, causing knocking. The octane number is a comparison of a fuel's burn properties to isooctane (pure 100 octane).

A way to increase a car engine's power is by increasing compression. Cars with lower compression engines can use 87 gas (equivalent to 87:13 octane:heptane). Cars with higher compression engines (such as BMWs) need 91 gas (equivalent to 91:9 octane:heptane) to ensure burning, not premature exploding.

By using a lower grade of gas, you are forcing the engine to run below its potential. Athletes can survive on bread and water like the rest of us too, you know.

528i
03-13-2005, 01:57 AM
The engine uses lead-free gasoline only. Required fuel: Premium Unleaded Gasoline, Min. 91 AKI.

I always find it funny when people think they know better than all the engineers at BMW. :dunno:

AsianImage
03-13-2005, 12:56 PM
I find the GAS QUESTION asked and debated constantly on pretty much every forum. I moderate at a sportbike forum sometimes, but I dont go on as much as I sold my bike. Anyways....street bikers argue over octane all the time. I see both sides of the argument and I swear everytime someone has one professional/academic reason one way, there is just a valid counter reason. I put premium in my car because I like to follow the manual and I THINK my engine would perform with better gas.

My mom...has a 2003 BASE model Toyota Corolla. She consistentely puts SUPER/PREMIUM gas in her car. I always tell her stop wasting money, your car does not need it etc. She says she FEELS better putting better gas in her vehicle. Her car is now 2 years old with UNDER 30K miles on it. She drives about 3 miles to work and never goes anywhere.

MMME30W
03-13-2005, 03:47 PM
I always find it funny when people think they know better than all the engineers at BMW. :dunno:

Where have you been, it is a well established fact that Internet message boards are way more knowledgeable about these cars than the manufacturer...sheesh! :rolleyes:








j/k :angel:

dagoo98
03-14-2005, 08:44 AM
Remember there is no ocdtane in gasoline. The number is just a measure of how bad the gasoline burns. The higher the octane the worse the gasoline burns. If your bimmer runs without knocking on 89 aki then use that forever. It wont hurt anything by using the better lower octane gasoline if the engine doesnt ping. If it does ping then you can retard the timeing until it doesnt ping. That is what I have been doing for three years now and mine is running fine. The piezolectirc antikniock sensors on the top of the engine retard the timeing all by themselves so there is not need for me to retard timing. I get to use the best quality gas which is the lowest octane my bimmer can burn without pinging. That is optimal efficiency.


Is this a joke? :confused: Retarding the engine timing by definition means decreasing performance. The knock sensors retards the timing to avoid pre-detonation because of the use of poor fuel but as a consequence performance decreases because its not at the optimal timing configured by BMW engineers. If you drove the same exact car running on premium after driving yours you would notice a difference. But who knows, maybe you know something BMW engineers don't. :dunno:

dagoo98
03-14-2005, 08:49 AM
BMW uses the term "Premium Unleaded Gasoline" with the knowledge that state laws
vary with regard to the octane that can be advertised as "premium". 89 probably
represents the lowest end of the range of fuel commonly advertised as premium in
the U.S., so any fuel labeled premium will meet the minimum specification. To
answer the original question, no, 89 octane won't hurt his car, and yes, he's
wasting money buying 92. The only time higher octane is of any benefit is if the
car pings on the recommended grade, the timing is advanced, compression is higher
than stock, or the car has forced induction. Pinging occurs when the spark
occurs too early in the cycle. If the fuel/air charge is not compressed enough
(i.e. harder to light) the charge explodes rather than burning at a controlled
rate. The two means of eliminating this condition are to a) use higher octane
fuel which is more resistant to ignition and burns slower and cooler (roughly 1
degree per point of octane) or b) retarding the ignition timing. This is exactly
what happens when the knock sensor detects pinging. In response, the computer
pulls out timing to prevent the pinging. What he means by "overkilling" is that
92 is overkill for his engine, i.e. more than is needed. It won't hurt it, but
it doesn't do any good either. If it makes you feel better to put premium in
your car, knock yourself out (yes, pun intended!)

http://member.rivernet.com.au/btaylor/BMWText/technical/PingingAndHiOctane.html


I've come to the conclusion that people will never change there minds about the gas they use in their cars so to each its own. Personally, I will always use premium gas in my car unless its a car built for regular like a Ford expedition or a similar vehicle.

shaftdrive
03-14-2005, 04:56 PM
Gasoline is composed of a bunch of different hydrocarbons, such as heptane (7 chained carbons) and octane (8 chained carbons). Octane burns and handles compression well. Heptane explodes and does not handle compression well, causing knocking. The octane number is a comparison of a fuel's burn properties to isooctane (pure 100 octane).

Actually, isooctane is better visualized as 2,2,4-trimethylpentane for this purpose.
The more complex the hydrocarbon, the more the resistance to detonation.
Heptane, in comparison, is much simpler, being a simple straight-line alkane.
It detonates quite readily, in comparison.
REFERENCE: http://www.chevron.com/prodserv/fuels/bulletin/motorgas/3_refining-testing/Default.asp

But these are just reference mixtures.
If I remember correctly, of the 500 or so hydrocarbons in a typical batch of gasoline,
there is little actual octane and heptane in the stuff at the pump.
Think of it this way. Would we really want to burn 91% 2,2,4-trimethylpentane (i.e., isooctane) in our BMW?
What we want is something that detonates "like" a 91% : 9% mixture of 2,2,4-trimethylpentane : heptane.

Detonation is just one (of very many) properties of gasoline.

In my personal unsubstantiated opinion, most of the rest of the properties are similar
whether it be 80 AKI or 110 AKI, advertising for Techron(tm) be damned.
So, the only reason, IMHO, to choose 91 AKI is if the BMW needs it by design for detonation purposes.
If the same car runs fine on 87 (i.e., no detonation with no retardation),
then the best fuel for that car is 87 AKI (as long as it's not being retarded).

I haven't read it in years, but, the definitive FAQ on the composition & properties of automotive gasolines
can be found in the renowned four-part gasoline FAQ by Bruce Hamilton,
of which part three deals exclusively with octane ratings:
http://www.faqs.org/faqs/autos/gasoline-faq/part3/

shaftdrive
03-14-2005, 05:03 PM
If the same car runs fine on 87 (i.e., no detonation with no retardation),
then the best fuel for that car is 87 AKI

What I'd like to know, being new to BMW automobiles, is:
How can I tell if the antiknock sensors are retarding the timing under load?

Is there an easy method to tell while driving?
Or can it this only be tested in the shop (under load perhaps?) with a timing light?

Does anyone out there know how to tell when the antiknock sensors retard the timing while driving the BMW?

http://www.chevron.com/prodserv/fuels/bulletin/motorgas/img/500/fig_3-3.gif

FenPhen
03-15-2005, 01:41 AM
But these are just reference mixtures.
If I remember correctly, of the 500 or so hydrocarbons in a typical batch of gasoline,
there is little actual octane and heptane in the stuff at the pump.
Think of it this way. Would we really want to burn 91% 2,2,4-trimethylpentane (i.e., isooctane) in our BMW?
What we want is something that detonates "like" a 91% : 9% mixture of 2,2,4-trimethylpentane : heptane.Yep. This is what I said, but not in so many words. :thumbup: (It also explains how you end up with fuel that has 110+ octane ratings.)

In my personal unsubstantiated opinion, most of the rest of the properties are similar
whether it be 80 AKI or 110 AKI, advertising for Techron(tm) be damned.I'd buy that, regarding the gas part. Sources I've found say gasoline fuels of ratings in the 87-93 range have very close to the same amount of stored energy, regardless of octane rating (detonation property), though I couldn't find specific numbers. However, Techron is an additive package, and its effects on engine health and performance should be considered separately from the fuel grade.

So, the only reason, IMHO, to choose 91 AKI is if the BMW needs it by design for detonation purposes.
If the same car runs fine on 87 (i.e., no detonation with no retardation),
then the best fuel for that car is 87 AKI (as long as it's not being retarded).Yes. I'd bet almost all the people here that say to use premium would agree with you entirely on this point, as well as people that have written professional articles on when to use premium. But apparently, the manual saying, "required fuel: premium unleaded gasoline, min. 91 AKI (anti knock index)," is not good enough for some people. :rolleyes:

dagoo98
03-16-2005, 08:48 AM
There are few things in life that I am unable to make sense of. Two of the items that reside on that list are the following: why do people buy luxury cars and then drive them constantly with the tank on E? The second item is why would people with luxury cars designed for premium gas put anything less than premium gas in their car? :dunno:

If anyone can offer any answers to these questions I would be appreciate it because the logic behind these two behaviors escapes me.

djlfp
03-16-2005, 09:14 AM
There are few things in life that I am unable to make sense of. Two of the items that reside on that list are the following: why do people buy luxury cars and then drive them constantly with the tank on E? The second item is why would people with luxury cars designed for premium gas put anything less than premium gas in their car? :dunno:

If anyone can offer any answers to these questions I would be appreciate it because the logic behind these two behaviors escapes me.
My guess is that some are status seekers who have spent way more on their cars (and other things) than they should have and are constantly short of money. Others were able to afford their cars because they are frugal and that might explain why they use regular gas if there are no apparent adverse consequences. Those who run it on empty may have reached the stage in their lives when they no longer purchase green bananas. :dunno:

The one thing I can say for sure is that people are interesting. :thumbup:

mark07960
03-16-2005, 03:05 PM
Car and Driver magazine did some work on octane levels a couple of years ago. They even used a BMW M3 as one of the test cars.

Basically, the article says it makes no difference to the engine as to what octane is used, as these modern engines compensate electronicly for the differences in fuel burning characteristics.

But, there is a slight performance loss, when moving from a higher octane level to a fuel with a lower octane rating. For the M3 the difference between premium and regular was a 6% reduction in performance, as measured by the time it took to accelerate from 0 to 120 mph.

Here is the link to the article:
http://www.caranddriver.com/article.asp?section_id=4&article_id=3604&page_number=1

FireWalker
03-16-2005, 03:07 PM
:yawn: What I'd like to know, being new to BMW automobiles, is:
How can I tell if the antiknock sensors are retarding the timing under load?

Is there an easy method to tell while driving?
Or can it this only be tested in the shop (under load perhaps?) with a timing light?

Does anyone out there know how to tell when the antiknock sensors retard the timing while driving the BMW?

http://www.chevron.com/prodserv/fuels/bulletin/motorgas/img/500/fig_3-3.gifHere we go again! :rofl:
A simple issue WAY overanalyzed and turned into a rocket science.
Is it really necessary to know the molecular structure of various fuels :yawn: to be able to decide what gas to use? Heck, NO!
The reason it is so hard to squeeze any extra HP from current BMW engines via software alone, is because they are already so well tuned.
So you don't need a degree in chemistry or a "timing light" to figure this out, BMW has ALREADY performed all the testing for you.
And what they are telling you, is that for their current high compression highly tuned engines, the OPTIMAL fuel is Premium 91 Octane Unleaded or higher.
Can the car run on 87 Octane? Sure, at the expense of performance, fuel efficiency, hotter engine, etc., etc.
SO ARE THE FEW DOLLARS SAVED WORTH SACRIFICING EVEN SOME PERFORMANCE? FOR THOSE WHOSE ANSWER IS "YES", PERHAPS THE ROUNDEL REPRESENTS "THE ULTIMATE SHOWOFF MACHINE" INSTEAD OF "THE ULTIMATE DRIVING MACHINE". :bustingup

FenPhen
03-16-2005, 05:20 PM
Car and Driver magazine did some work on octane levels a couple of years ago. They even used a BMW M3 as one of the test cars.Where is the damn repost smiley??

Here's a reposted response for you:

A way to increase a car engine's power is by increasing compression. Cars with lower compression engines can use 87 gas (equivalent to 87:13 octane:heptane). Cars with higher compression engines (such as BMWs) need 91 gas (equivalent to 91:9 octane:heptane) to ensure burning, not premature exploding.

Yes, the car can electronically compensate by adjusting timing, but it can't adjust its compression stroke. Mechanically, it has to do the same thing, which always threatens premature detonation, but the car has to rely on electronics to avoid knocking. Instead of using the proper fuel that lets the engine run stably, you choose improper fuel and require the engine to hold itself back to not damage itself.