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Alright i was just reading my manual, and it says that BMW engines are not bult to use additives. So does this mean i am not supposed to be filling up at stations like Petro Canada (uses tactrol) and chevron (uses techron) This doesnt make any sense to me since the additives are supposed to be better for our engines. Please help because i have been filling up with 94 octane w/ tactrol since i got my car!!
 

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Automobile gas has additives in it regardless of brand. BMW manual is probably referring to octane boosters and such.
 

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the dealer told to use 89 instead of 94 and if u already don't know, gas is gas. So no matter what station u r at remember that. I am a chemical engineering major trust me!
 

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sanman10535 said:
the dealer told to use 89 instead of 94 and if u already don't know, gas is gas. So no matter what station u r at remember that. I am a chemical engineering major trust me!
My car feels dead with anything below 91. The manual also states premium, and both my car (330i) and my Fathers 740il feel like they lost alot of power with 89. And I really don't think gas is gas, because there are tons of different chemicals added, or taken out, that can determine how a car is run.

As for the original post, use any gas you like, but I prefer 76 the most.
 

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sanman10535 said:
the dealer told to use 89 instead of 94 and if u already don't know, gas is gas. So no matter what station u r at remember that. I am a chemical engineering major trust me!

I have tried low octane fuel before, and I noticed a considerable difference in the car. It feels dead. Its odd that you didn't notice this also, because the dozen or so times this question has been posted on this board, everyone notices a huge difference.
 

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Crazy Boy
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high compression engines like our bmws get a lot of "knocking" with low octane gasoline. this is because the high pressure causes it to spontaneouly combust inside the chamber instead of letting the spark plugs do their work. thats why alot of these german cars and forced induction cars especially benefit from higher octane gas. after a while its just over kill though.
 

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Coldintake said:


My car feels dead with anything below 91. The manual also states premium, and both my car (330i) and my Fathers 740il feel like they lost alot of power with 89. And I really don't think gas is gas, because there are tons of different chemicals added, or taken out, that can determine how a car is run.

As for the original post, use any gas you like, but I prefer 76 the most.
Gas is gas, because ALL gas stations share a common pipeline.
 

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sanman10535 said:


Gas is gas, because ALL gas stations share a common pipeline.
Not trying to be rude... but all gas doesn't necessarily come from the same place and there are such things as refineries that refine gasoline. Additives such as MTBE can influence a positive behavior in our cars.

But if you do look far back enough, yea, the same dinosaurs died that are now fossil fuels. :dunno:
 

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Coldintake said:


Not trying to be rude... but all gas doesn't necessarily come from the same place and there are such things as refineries that refine gasoline. Additives such as MTBE can influence a positive behavior in our cars.

But if you do look far back enough, yea, the same dinosaurs died that are now fossil fuels. :dunno:
That was just a big sum up of where gas comes from. Sure gas stations love to tell u that our gas is better than others cause we put certain additives in it to make your car engine run better:thumbdwn: Sorry if that is the case then I would be filling up at mobile 1 all the time. The additives they put in the cause has NO effect on how your engine will run.

Perhaps I would post our lab experiment on this, but I do not want to put you all to sleep. Anywayz, this is our research data so fill free to critique it.:D
 

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sanman10535 said:


That was just a big sum up of where gas comes from. Sure gas stations love to tell u that our gas is better than others cause we put certain additives in it to make your car engine run better:thumbdwn: Sorry if that is the case then I would be filling up at mobile 1 all the time. The additives they put in the cause has NO effect on how your engine will run.

Perhaps I would post our lab experiment on this, but I do not want to put you all to sleep. Anywayz, this is our research data so fill free to critique it.:D
I would be curious to see your lab data and compiled results. Anyone who gets bored with it can go to another thread.
 

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Doesn't BMW have octane sensors in the engine that limit your engine power if you use low octane?

That’s what the Service Manager at my Dealership said.

Well I don't know but I used 87 ones and my car ran ****ty. Slow and boggy the whole time. Then next time I fuelled up I used 91 witch is the high they sell here and the car just jumped. Right out of the gas station it had so much power it felt like a different car. Now all I use is 91 and I still feel the boost of power when I fill up.
 

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The Federal Gov't's take on Gas

From the Federal Trade Commission:

The Low-Down on High Octane Gasoline

Are you tempted to buy a high octane gasoline for your car because you want to improve its performance? If so, take note: the recommended gasoline for most cars is regular octane. 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 car perform better, go faster, get better mileage or run cleaner. Your best bet: listen to your owner’s manual.

The only time you might need to switch to a higher octane level is if your car engine knocks when you use the recommended fuel. This happens to a small percentage of cars.

Unless your engine is knocking, buying higher octane gasoline is a waste of money, too. Premium gas costs 15 to 20 cents per gallon more than regular. That can add up to $100 or more a year in extra costs. Studies indicate that altogether, drivers may be spending hundreds of millions of dollars each year for higher octane gas than they need.

What are octane ratings?
Octane ratings measure a gasoline’s ability to resist engine knock, a rattling or pinging sound that results from premature ignition of the compressed fuel-air mixture in one or more cylinders. Most gas stations offer three octane grades: regular (usually 87 octane), mid-grade (usually 89 octane) and premium (usually 92 or 93). The ratings must be posted on bright yellow stickers on each gasoline pump.

What’s the right octane level for your car?
Check your owner’s manual to determine the right octane level for your car. Regular octane is recommended for most cars. However, some cars with high compression engines, like sports cars and certain luxury cars, need mid-grade or premium gasoline to prevent knock.

How can you tell if you’re using the right octane level?
Listen to your car’s engine. If it doesn’t knock when you use the recommended octane, you’re using the right grade of gasoline.

Will higher octane gasoline clean your engine better?
As a rule, high octane gasoline does not outperform regular octane in preventing engine deposits from forming, in removing them, or in cleaning your car’s engine. In fact, the U.S. Environmental Protection Agency requires that all octane grades of all brands of gasoline contain engine cleaning detergent additives to protect against the build-up of harmful levels of engine deposits during the expected life of your car.

Should you ever switch to a higher octane gasoline?
A few car engines may knock or ping — even if you use the recommended octane. If this happens, try switching to the next highest octane grade. In many cases, switching to the mid-grade or premium-grade gasoline will eliminate the knock. If the knocking or pinging continues after one or two fill-ups, you may need a tune-up or some other repair. After that work is done, go back to the lowest octane grade at which your engine runs without knocking.

Is knocking harmful?
Occasional light knocking or pinging won’t harm your engine, and doesn’t indicate a need for higher octane. But don’t ignore severe knocking. A heavy or persistent knock can lead to engine damage.

Is all "premium" or "regular" gasoline the same?
The octane rating of gasoline marked "premium" or "regular" is not consistent across the country. One state may require a minimum octane rating of 92 for all premium gasoline, while another may allow 90 octane to be called premium. To make sure you know what you’re buying, check the octane rating on the yellow sticker on the gas pump instead of relying on the name "premium" or "regular."

For More Information

The FTC works for the consumer to prevent fraudulent, deceptive and unfair business practices in the marketplace and to provide information to help consumers spot, stop and avoid them. To file a complaint or to get free information on consumer issues, visit www.ftc.gov or call toll-free, 1-877-FTC-HELP (1-877-382-4357); TTY: 1-866-653-4261. The FTC enters Internet, telemarketing, identity theft and other fraud-related complaints into Consumer Sentinel, a secure, online database available to hundreds of civil and criminal law enforcement agencies in the U.S. and abroad.
 

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Let me explain...

Well, unfortunately BMW does recommend high-octane (I can't remember if they say the lower limit is 91 or 92 octane). Our engines are fairly high compression, and DO need the extra octane to avoid detonation (knocking). When you put a lower octane in your car, the engine will detect knocking and retard the ignition timing to lower the cylinder temps (one of the components of detonation). When this timing is retarded, you lose power and efficiency. When you lose efficency, you lose gas-mileage. So all of you that are buying regular because its cheaper (come on its not exactly a cheap car guys) you might want to check you MPG against it, you may not be saving as much as you think.

No, No, it takes to long, let me sum up...
Yes, if a car only needs regular, your wasting money until it starts knocking. Our cars, from the manufacturer, state a requirement of 91+ octane to prevent knocking and subsequent ignition retarding.
 
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