How many of you run 87 octane fuel?

[nomad]

The problem is, you do not know if yours is one of the better or worse ones.  How do you know if you did not get a piston with a slightly thinner casting in the top? Slightly deformed or more casting flash...

...You drive a high end sports sedan that needs higher end parts.

I'm not arguing anymore, just thought these two assertions did not really go together.

[sheepdog]

Get real. We drive $1000 beaters. This is no "high end sports car". It was the poverty spec bmw when it was new, its a 17 year old beater today that happens to be fun to drive and gets pretty good mileage. I'm sick and tired of all the "get a Honda if you can't afford a bmw" nonsense Have you looked at how much a 92-95 civic costs? If you want to stay on the safe side and use 91 octane all the time go ahead. Theses nothing wrong with that. But this whole theory that we are somehow not deserving of the all mighty BMW because we happen to run 87 octane is just plain BS. I'm willing to bet 90% of the 10+ year old bmws on the road are being fed 87 octane without a second thought. The first owner might have used 91 octane but once the car hits the used car market, all bets are off.
I filled up the tank at lunch today. 31.5 mpg on 87 octane.
cheers
Justin

Wrong, so wrong. Way to miss the point.

You drive a $1000 beater that was built as a high end sports sedan. It still requires parts like a high end car. You could almost buy 2 decent Mustangs for the price of a 318IS back when they were new.

When this car is 50 years old will it still be a beater? Current price has NOTHING to do with what a car requires for maintenance. It may be only a beater to you, but the engine and specs have not changed on it.

Do you really think the octane requirement goes down with age?


Maintenance has nothing to do with being a BMW. It has to do with what the car was designed for. If you drive a 1974 Mustang that requires premium, it still needs premium regardless of how old the car is or big of a pile of shit the car is. It's just an old Porsche, BMW, Mercedes, Ferrari, does not matter, they still require what they did when new. It being a BMW has to do with what you expect from it. It is not a Honda or Toyota you can just put whatever you feel like in it and expect it to keep running well.


Sorry, but people who think like you do piss me off. Just because something is old does not mean it is worthless or can be treated like crap and expect to keep performing as it once did. As a car ages it requires more, not less care. It is ass-backwards thinking.


As for what the Honda costs... B.S.
Have you tried finding an e30 in comparable shape? Also, take a look as total cost of ownership, not just initial buy in. HUGE difference there. If you find me a NICE e30 318IS for the cost of a 1992 Civic, let me know. I can find several Civics for around $3k (or less) in excellent shape, 318IS, good luck.

[EN318isPDX]

Wrong, so wrong. Way to miss the point.

You drive a $1000 beater that was built as a high end sports sedan. It still requires parts like a high end car. You could almost buy 2 decent Mustangs for the price of a 318IS back when they were new.

When this car is 50 years old will it still be a beater? Current price has NOTHING to do with what a car requires for maintenance. It may be only a beater to you, but the engine and specs have not changed on it.

Do you really think the octane requirement goes down with age?


Maintenance has nothing to do with being a BMW. It has to do with what the car was designed for. If you drive a 1974 Mustang that requires premium, it still needs premium regardless of how old the car is or big of a pile of shit the car is. It's just an old Porsche, BMW, Mercedes, Ferrari, does not matter, they still require what they did when new. It being a BMW has to do with what you expect from it. It is not a Honda or Toyota you can just put whatever you feel like in it and expect it to keep running well.


Sorry, but people who think like you do piss me off. Just because something is old does not mean it is worthless or can be treated like crap and expect to keep performing as it once did. As a car ages it requires more, not less care. It is ass-backwards thinking.


As for what the Honda costs... B.S.
Have you tried finding an e30 in comparable shape? Also, take a look as total cost of ownership, not just initial buy in. HUGE difference there. If you find me a NICE e30 318IS for the cost of a 1992 Civic, let me know. I can find several Civics for around $3k (or less) in excellent shape, 318IS, good luck.

Wow! Too many good points! I hope this is the end of this lame thread! Thanks for representing the M42! These guys need to swap to M20 i believe they would be much better off!

[mkodama]

Sorry, but people who think like you do piss me off. Just because something is old does not mean it is worthless or can be treated like crap and expect to keep performing as it once did. As a car ages it requires more, not less care. It is ass-backwards thinking.


As for what the Honda costs... B.S.
Have you tried finding an e30 in comparable shape? Also, take a look as total cost of ownership, not just initial buy in. HUGE difference there. If you find me a NICE e30 318IS for the cost of a 1992 Civic, let me know. I can find several Civics for around $3k (or less) in excellent shape, 318IS, good luck.

You sure are aggressive for a site admin...

I think the issue is less of the car being old, but the current market value.  If I just look on the local craigslist ads, it's easy to find one for not much.  Just right now there is a 1991 white 318is with 160K miles and in good condition for $2800.  I bought mine for around $1600, and I've seen "O.K." condition cars for less than $1000.  In short, it's hard for people to spend much money on a car that isn't of much value to them and easy to replace.

Sorry, I just felt like I had to defend Justin since you are being a little too forceful in pushing your beliefs onto others.

[nomad]

Oh come on all of you guys. it's the interweb, feelings are for kids.
Let's make sure we keep the discussion to the mechanical and engineering aspects of the topic. What is this going to be... Jerry Springer?

OK, there are lots of detailed scientific reasons why the engineers chose the octane rating new. There are also plenty of reasons why they need specific care used that they did not need new.
There are also ways of "re-engineering" certain aspects from an enthusiast's perspective as well.

Cars are designed with a certain give and take in order to please the general population. If we only wanted sports cars then they'd have low/stiff suspensions, stripped interiors and peaky powerbands. But the E30 was a combo of fun luxury and the M42 was an option for the "commoner".

Let's stick to the details, do a little research before we post and provide valuable, real knowledge.

[mkodama]

Oh come on all of you guys. it's the interweb, feelings are for kids.
Let's make sure we keep the discussion to the mechanical and engineering aspects of the topic. What is this going to be... Jerry Springer?

OK, there are lots of detailed scientific reasons why the engineers chose the octane rating new. There are also plenty of reasons why they need specific care used that they did not need new.
There are also ways of "re-engineering" certain aspects from an enthusiast's perspective as well.

Cars are designed with a certain give and take in order to please the general population. If we only wanted sports cars then they'd have low/stiff suspensions, stripped interiors and peaky powerbands. But the E30 was a combo of fun luxury and the M42 was an option for the "commoner".

Let's stick to the details, do a little research before we post and provide valuable, real knowledge.

JERRY! JERRY! JERRY!

haha, jk, very well said nomad.

[beegeezy]

You sure are aggressive for a site admin...

Huh? The guy seems to know what he is talking about and likes the cars, what does his being the admin have to do with his views? Its not like he banned anyone for their opinion, we're all just having a discussion.

[Cobra Jet]

the sky is falling, the sky is falling!

...

IMO, I fail to see the connection of ANY engine, regardless of type, HP, # of cylinders, compression, etc failing due to the SOLE sustained use of a lower or higher octane fuel.  

Engine wear, tear and failure rate can be attributed to MANY variables - but to sit back and state that someone's engine will outright fail OR will possiby expire at X,XXX, XX,XXX or XXX,XXX miles just because they use Brand X fuel that has a lower or higher octane rating other than what is stated in the "Owner's Manual" is purely ridiculous.

I want to see an engine that has failed SOLEY due to the octane level of the fuel that was used.  Such a failure should have facts to back up that the SOLE and ONLY factor due to such a failure was 100% attributed to the type of fuel used and that all other engine internals, externals, sensors, FPR psi, oil psi, coolant temp, oil viscosity, injector spray pattern and so forth were within factory operating spec, factory tolerances & it was maintained by proper maintenance as stated in the same owner's manual.  Show me an M42 that has failed prematurely and was proven to have failed without any doubt due to only using a lower octane fuel other than what was recommended by BMW.


I don't see why anyone would think the topic of this thread is "stupid" - why, because others have successfully used 87 octane in a N/A stock engine with no adverse effects and don't feed into the "you HAVE to do this or else" hype?  I think the thread has generated a ton of good, valuable and informative info from everyone who had input.  

When this car is 50 years old will it still be a beater?

YES - to some and to some the car will still be just as "disposable" just like many others out there.  As proven by some Members on here, some of the M42's can be had for as little as $300.00... and any used vehicle is only worth as much as someone is willing to pay for it.  You can still pay $3k & higher for an M42 and end up w/ one that will still need mechanical work, could have an unexpected failure or one that was not maintained properly.  The market varies based on geographic location, miles on vehicle, overall condition and if the buyer/seller are in agreement.  Some are used as beaters, some are garage queens and some are restored former beaters...

[EN318isPDX]

To each his own but I'm going to keep running the CORRECT octane gas because my car is a high compression 4 cylinder. If it was a pos American v8 I might run crappy gas

[sheepdog]

Oh, I'm sorry, I thought this was a site meant for enthusiasts, not "I bought a BMW thinking it was cheap" or  "how to keep your beater running as cheap as possible".

I never said it will fail at X number of miles.
Can we prove there was nothing else at fault, nope.

Is there scientific proof that you cannot hear all detonation, YES.
Is there scientific proof that detonation causes engine failures, YES.



And I never knew there was a rule that site admins could not be salty from time to time. I thought they were human just like the next person.

[shutter]

Salty admins rule!

I don't daily drive my car, so it's a bit easier for me to run premium since I don't fill up much luckily.  We're up to $4.25 for regular downtown!!  Not sure where premium is at, I filled a full tank over mother's day in the sticks that should last me a bit.

Anyways, I have enough blood, sweat, and tears, let alone funds in my car to go by the owner's manual.  To each their own though I guess.  been reading this thread for a bit, it's been a fun one for m42club.com =)  Finally felt like chiming in.  It is a high-compression, high-revving 4 banger.  I'd rather have it to spec, so I can rev it without any nagging worries in the back of my mind.  To me, that's worth the extra $.20 a gallon.

[nomad]

I thought they were human just like the next person.

And that's where you went wrong.


OK, seriously. There is evidence that engines get irreparable damage from using too low of an octane. Predetonation needs to be controlled in all circumstances. Why the heck do you think there is even a computer controlling things? Fuel maps, timing advancements etc are all ways to control what is going on in the cylinder to make sure it is running correctly, that the spark ignites the fuel ,mix at the right time and that the flame front and expanding gasses impact the piston at the right moment in the stroke. If you don't think predetonation/preignition (also subsequent combustion temps) does not harm not only the efficiency of the engine but the wear and tear on piston heads, wrist pins rods, crank bearings and even cranks then you just don't know enough about internal combustion engines yet to respond effectively. Come on, do some research, go to a library (gasp!) or a bookstore and read up on the technology.

Why did BMW add knock sensors to the next iteration of the M42? Because the more control you have over ignition, fuel, timing and the more info you can read about what's going on in the cylinder the better you can run.

You need to know the answer to these questions before you can really analyze this topic effectively:
What is the relationship to cylinder compression and higher octane? How about in relation to forced induction engines?  what does running lean or running rich mean? What are the dangers/issues of either? What is timing advance/retard and how does it relate to top dead center? What is the relation between fuel octane and ignition speed (flame front)?

[christophbmw]

Oh, I'm sorry, I thought this was a site meant for enthusiasts, not "I bought a BMW thinking it was cheap" or  "how to keep your beater running as cheap as possible".

Sheepdog, i love your posts, very educated compared to what most other people are saying.....but i have to disagree with you on your last post. i think the E30 is a cheap car for what you get, they dont cost much to maintain, they are fun to drive....and compared to most japanesse cars, they are very cheap, the only thing that makes most japanesse cars "cheap" to own is if you dont do regular maintnece on them they still run, BMW's on the other hand need there attention, thus, to the general public....they are "expensive" to own (because most people dont take care of their cars). Would you agree?

Another thing, i work in the automotive industry right now (gotta pay for college somehow) and i get this octane rating question alot! and not just for BMW's, i get porsche, mercedes, volvo, and Audi customers coming up to me and asking: do i have to run premium? here is my answer to keep it simple:
The more you can advance timing, the more power you get out of the engine, the higher the octane, the more it resists burning, so therfore you can advance the ignition timing more.

....i know, iknow there is more variables to it, but to the average joe it makes sense so im sticking to it. Did you know that BMW actually invented knock sensors? i little FYI:).

[nomad]

here is my answer to keep it simple:
The more you can advance timing, the more power you get out of the engine, the higher the octane, the more it resists burning, so therfore you can advance the ignition timing more.

Thank you. Education is paying off already.


Also applies to forced induction. It is limited to a certain point when the strength of parts and mechanical limitations of the engines but yeah, most people just want one simple answer.

[beegeezy]

the sky is falling, the sky is falling!

...

IMO, I fail to see the connection of ANY engine, regardless of type, HP, # of cylinders, compression, etc failing due to the SOLE sustained use of a lower or higher octane fuel.

Really? I couldnt see a fuel that was too high of an octane causing engine problems, but there is plenty of evidence to prove that too low of an octane can hurt your engine(since we're talking about ANY engine here).