premium gas

[jterz91]

how important is putting premium in the 1? does it need it

[BlueC]

If the manual says it's required, then it is required.

[Monterra]

Do you really want to find out by saving 20 cents a gallon?
Best case: Loss of hp
Worst case: Potential engine damage over time
I don't put much stock in "top tier" bs. Some do, I haven't noticed any variance what so ever although I don't put no-name stuff in either. Sunoco/Hess/Shell/Mobil all seem to run fine.

[Judge]

I believe the 128 uses "midgrade" not "premium" if I'm not mistaken.

[Qunadry]

Why would you buy a BMW and then risk damage to it by using non-premium gasoline? I'm not trying to be a snob, but great engines deserve the proper fuel.

[jkp1187]

From the manual (p. 105):

Super Premium Gasoline/AKI 91

This gasoline is highly recommended.

However, you may also use gasoline with less AKI. The Minimum AKI Rating is:

> 128i: 87
> 135i: 89

If you use gasoline with this minimum AKI rating, the engine may produce knocking sounds when starting at high outside temperatures. This has no effect on engine life.

<!> Do not use any gasoline below the specified minimum fuel grade. Otherwise the engine could be damaged.

In other words: 87 octane should be okay for your 128i. Don't go below 89 with a 135i.

[ad78]

Get a membership at sams club! At least 93 is cheaper.
Dont risk...

[tm30]

Premium no matter what. You can get by on 87, but did you buy this car just to get by on it?

[oasis3582]

Never get why anyone would buy a $30k car, then skimp 20c per gallon.

[jeremyc74]

Originally Posted by jkp1187

From the manual (p. 105):



In other words: 87 octane should be okay for your 128i. Don't go below 89 with a 135i.

Quoted for truth. You don't have to run Premium in the car, and it's not even remotely "risky" to run 89 in it, you're just not going to get the full power out of it.

(That statement is made assuming it's running on the stock tune. On a tuned car you may very well be running the chance of engine damage using lower octane fuels)

[Excitmnt94]

you will not only make less of power than you would running 93, but you also will not get the same kind of fuel economy either. you will effectively save 15-20 cents a gallon running midgrade on a 135i, but your economy will suffer to the point that it will cost you more running the cheaper gas. not worth it in the turbo...makes ZERO sense/cents. just run the good stuff. you getbetter power...better fuel economy...no brainer.

[jeremyc74]

Originally Posted by Excitmnt94

you will not only make less of power than you would running 93, but you also will not get the same kind of fuel economy either. you will effectively save 15-20 cents a gallon running midgrade on a 135i, but your economy will suffer to the point that it will cost you more running the cheaper gas. not worth it in the turbo...makes ZERO sense/cents. just run the good stuff. you getbetter power...better fuel economy...no brainer.

That's not true at all. Octane rating only is about anti-knock properties, NOT energy content. Too many people here are under the impression that the octane rating is some sort of "quality" measure, and it's not. It's about how resistant a fuel is to ignition, which has much more effect on how much power an engine can produce than the fuel economy it's capable of at partial throttle.

[oldfatslow]

The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites. When gas ignites by compression rather than because of the spark from the spark plug, it causes knocking in the engine. Knocking can damage an engine, so it is not something you want to have happening. Lower-octane gas (like "regular" 87-octane gasoline) can handle the least amount of compression before igniting.

The compression ratio of your engine determines the octane rating of the gas you must use in the car. One way to increase the horsepower of an engine of a given displacement is to increase its compression ratio. So a "high-performance engine" has a higher compression ratio and requires higher-octane fuel. The advantage of a high compression ratio is that it gives your engine a higher horsepower rating for a given engine weight -- that is what makes the engine "high performance." The disadvantage is that the gasoline for your engine costs more.

http://auto.howstuffworks.com/fuel-e...uestion901.htm

[bluejaypanther]

Originally Posted by jeremyc74

That's not true at all. Octane rating only is about anti-knock properties, NOT energy content. Too many people here are under the impression that the octane rating is some sort of "quality" measure, and it's not. It's about how resistant a fuel is to ignition, which has much more effect on how much power an engine can produce than the fuel economy it's capable of at partial throttle.

There is a performance factor, it's just not intrinsic to the octane level. Some engines will detect the octane of the incoming gas and adjust the fuel injection/timing to be more or less aggressive accordingly, taking advantage of the resistance to ignition to produce more power.

[jeremyc74]

Originally Posted by bluejaypanther

There is a performance factor, it's just not intrinsic to the octane level. Some engines will detect the octane of the incoming gas and adjust the fuel injection/timing to be more or less aggressive accordingly, taking advantage of the resistance to ignition to produce more power.

No one said there wasn't a performance factor. Obviously if the ECU detects knock it's going to retard timing, which reduces power. That doesn't have anything to do with fuel efficiency at partial throttle though.

[e82vette]

premium give you better mpg anyways...why not
same $$$ at the end

[Ibi]

i fill it with premium; well Ultra 94 from Sunoco (you're spending an extra what $8 bucks;15/20 cents/L) ...you get way better mpg

[Qunadry]

According to the 1 series brochure I got from my dealer, the compression ratio for the 128i is 10.7 and 10.2 for the 135i. Therefore the 128i needs 93 octane more than the 135i.

[Tom K.]

Originally Posted by Qunadry

According to the 1 series brochure I got from my dealer, the compression ratio for the 128i is 10.7 and 10.2 for the 135i. Therefore the 128i needs 93 octane more than the 135i.

Not according to BMW, especially since factors other than CR come into play. So if you want to feed your 135i 87 octane, you do so at your own risk.

For the R1200RT motorcycle, BMW actually published a spec of 8% reduced peak HP using regular (Euro) 93 octane vs. premium 98 (US approx. 88 vs. 93). Of course, this is with an air/oil cooled motor with 12:1 compression, but the concept of reduced power due to computer managed timing adjustment is common to both bike and cage. Whether that translates into improved fuel economy in normal use is a good question, but anecdotal evidence seems to indicate that it does by at least 5~10%.
Tom

[jeremyc74]

Originally Posted by Qunadry

According to the 1 series brochure I got from my dealer, the compression ratio for the 128i is 10.7 and 10.2 for the 135i. Therefore the 128i needs 93 octane more than the 135i.

You're forgetting that the 135i is using forced induction, which effectively raises the compression ratio.

[Lisav123]

First of all the135i needs at least 92 octane im pretty sure, my vw gti was turbo needed at least 92 bcz itsa turbo, my mini cooper s needed at least 92 octane also bcz it is supercharged, and my 135i on the way is going to have at least 92 octane in it at all times, come on ppl im a 20yr old girl and i even kno that lol, and im guessin if its a 128i its not turbo or supercharged it could live without premium gasoline

[jeremyc74]

Originally Posted by Lisav123

First of all the135i needs at least 92 octane im pretty sure, my vw gti was turbo needed at least 92 bcz itsa turbo, my mini cooper s needed at least 92 octane also bcz it is supercharged, and my 135i on the way is going to have at least 92 octane in it at all times, come on ppl im a 20yr old girl and i even kno that lol, and im guessin if its a 128i its not turbo or supercharged it could live without premium gasoline

Manufacturers selling cars in the US have to build them to run at rated power on 91 octane. That's as high as premium goes in most of CA, and a few other states. The manual states that you can run on 89 with no problems, but you're not going to make rated HP.