1 series fuel questions

I am considering a 1 series convertible. Some people I have talked with claim it can run on regular gas while the dealer says mid-range. Others use regular with an octain booster. Your openions please.

Bob Q

The trick with gas is actually to use the lowest grade, without hearing any engine knock, or denotation on the spark plugs. You can run 43 octane if you want, as long as it doesn't knock. (Obviously I am exaggerating, but you get my point)

Your best bet is to try the lowest grade gas you can find, and run a full tank on it. If you get knock, if you getting any denotation, premature spark, etc. then you should go 1 step higher. Continue to go higher and higher until your car runs fine.

The worst thing you do to your car on a crappy tank of gas is black out your plugs. They will be cleaned by your higher grade gas once it gets put in.

id run premium fuel no reason to get cheap now you did buy a bmw

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Originally Posted by mr29

id run premium fuel no reason to get cheap now you did buy a bmw

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Yes. You've already spent some hard earned money, you should throw some away now. :-)

The manual says 87 octane is acceptable, but recommends 91 or higher for the 128i.
89 octane minimum for the 135i

The higher octane the gas, the more resistant it is to heat. That's why cars ask for higher octane gas, to resist RETARD, AND DENOTATION. Buying expensive gas just because you drive a BMW is stupid on a level I can't comprehend lol. Do yourself a favor and read a little about octane.

Originally Posted by bbowers825

The higher octane the gas, the more resistant it is to heat. That's why cars ask for higher octane gas, to resist RETARD, AND DENOTATION. Buying expensive gas just because you drive a BMW is stupid on a level I can't comprehend lol. Do yourself a favor and read a little about octane.

so your saying buy premium

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Originally Posted by mr29

so your saying buy premium

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Quite the opposite.

Been going back and forth between 89/91 on my '08 128/6MT and do notice a slight difference. Bit smoother/quicker on the 91..a bit more "grindy"on the 89. Not sure many would really notice, but I do. I think I'm just gonna stick to 91 or higher going fwd while fully realizing car is capable of being run on 87/89. Might as well do 91 and enjoy the ride..gas is so expensive anyway!

Originally Posted by bbowers825

The higher octane the gas, the more resistant it is to heat. That's why cars ask for higher octane gas, to resist RETARD, AND DENOTATION. Buying expensive gas just because you drive a BMW is stupid on a level I can't comprehend lol. Do yourself a favor and read a little about octane.

Aggressive post is aggressive!

If you get a 135i I would use the highest octane at the pump since it has a turbo(s) while the 128i does not.

Originally Posted by mryakanisachoad

Aggressive post is aggressive!

Gas, gas myths, and it's improper use is a pet peeve of mine.

Dont have a 1 series but I have a 5 series and my dads had lots of bmws right now an 08 5 series and everyone we've had at the house doesnt like to run on anuthing below premium and eventually gers top end noise and the noise goes away when putting back in premium

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The ignition will run more advanced with higher octane fuel giving better gas mileage. You might not need 93 but using 87 is a false economy. Want to run cheep gas listen to some guy on the internet or you can read the manual to see what the guys who designed & built the car recommend.

Originally Posted by bear-avhistory

The ignition will run more advanced with higher octane fuel giving better gas mileage. You might not need 93 but using 87 is a false economy. Want to run cheep gas listen to some guy on the internet or you can read the manual to see what the guys who designed & built the car recommend.

"Some guy on the internet"

http://www.google.com/webhp?sourceid...w=1920&bih=955

We're a forum. Were supposed to discuss this type of stuff, and come up with the best solution. If you're just going to blindly come into the thread, post "BMW SAIS DAT I SHUD USE 93, DAts waT i uSe Alyays!" you're not helping anyone make a decision.

Like I said before. Do yourself a favor and READ about gas. It's an incredibly simple subject that 90% of people fail to comprehend.

"Listen to your car's engine. If it doesn't knock
when you use the recommended octane, then
you are using the correct grade of gasoline. If
your engine runs well and does not knock or
ping when using a lower octane gasoline, there
will be no advantage in switching to a higher
octane."

Its not knocking because the knock sensors are cutting back on the ignition timing to keep it below the knock threshold. The sensor will detect knock before it becomes audible. When you reduce timing you reduce power & fuel economy. Therefore I would go with what the factory recommends & not some guy on the in internet who is saying what you want to hear that cheap gas is OK. Riding on the edge just below the knock threshold is how the JB4 manages its boost increases without scattering the engine all over the track.

I am sure the BMW engineers are recommending higher octane fuel then necessary just to increase the value of their oil stock portfolios or possibly to make the cars less attractive to the proponents of low octane fuel.

BTW anytime you want to match your engine building skills from the bare block up against mine please feel free to do so.

[QUOTE=bbowers825;7367907"Listen to your car's engine. If it doesn't knock
when you use the recommended octane, then
you are using the correct grade of gasoline. If
your engine runs well and does not knock or
ping when using a lower octane gasoline, there
will be no advantage in switching to a higher
octane."[/QUOTE]

Good advice - for 30 years ago!!

But as bear said, modern motors now have knock sensors which will cause the ECU to retard timing before knocking is heard - resulting in reduced power and gas mileage. How much is open to question, but when BMW brought out the R1200RT motorcycle in 2005, they actually quoted peak horsepower using both 93 and 87 octane and the difference was 8%. The US BMW car motors are optimised for 91 AKI but may be run on 89 (turbo) or 87 (non-turbo) respectively.

For my 328i (and 128i and Z4 and Z3 before it), I use a 10% price differential as a determining factor. That is,under the assumption that ritarding the timing will result in no worse than a 10% power/mileage penalty (probably much less in real life), I use 87 octane when 93 is priced 10% higher. If less than 10%, I stick with the recommended (by BMW, not some internet guy) 91 or better as it makes more financial sense. And since in my area, midgrade (89 octane) is generally priced halfway between 87 and 93, it makes no sense to use it, especially in a NA motor.

Tom

Interesting point. Not sure if they still post it but the last generation of the Honda Accord V6 had two BHP numbers listed about 10BHP apart with 87 & 91 octane. Its also easy to check out some JB4 dyno runs to see the difference fuel octane can generate.

About 30 years ago we had to deal with either vacuum/centrifugal or straight centrifugal advance distributers. Straight centrifugal were the choice for performance motors because of the low vacuum available off idle with bigger cams.

We use to use various sized stop pegs on the maximum advance position so we could get the best timing lead for the initial lead setting but limit overall advance to prevent detonation (knock). Various spring & centrifugal weight shape/weight were used to build the shape of the advance curve for maximum performance. This stuff is all done way better now by the ECU & sensors.

This article is a good read:

A Chemists View on Octane and Gasoline Brands

http://www.vettenet.org/octane.html

My son does follow his advice on switching top tier brands every 5000 miles on his 135i convertable.

Some more good info thanks to Nordic_Kat

http://www.bimmerfest.com/forums/sho...grade+gasoline

Follow up on the above:

http://www.bimmerfest.com/forums/sho...606&highlight=

Interesting article. Only issue with this debate is the 1979 350 came in two flavors 8.2 & 8.9 compression ratios. So the article is really about the additive packages not about octane requirements. With that compression ratio & a standard ignition system no reason the engine could not run OK on 87 regular. My 67 Corvette with various engines had an average 11.5 compression ratio ran on a regular basis at Englishtown on very high octane fuel.

this has turned into a great read and thread lots of good info here

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I agree it has! It just took almost 4 days of posting for someone else to come in and discuss it.

I am new here, my 135is 6MT convert is on a boat someplace in the Atlantic. I enjoy some give & take & hope to be active on the forum.