[tony176000]

Originally Posted by scrufy

Yawn another idiot. sorry to piss off everyone in this thread but your a bunch of idiots. different grade gas means nothing. What your car will run on based on compression ratio and timing is the only thing you ned to know. If your car manufacturer says 89 ROM then 91 ROM is a waste of money and will actually cause pitting on your valves.
Read up on this stuff.

Since you opened the door, let me drive a truck through it. You're the idiot buddy. If the number on the pump means nothing, why is it there? Why not put -32 AKI in your car or whatever, and let us know how that works out.

You have incorrectly summarized like 15 issues on the topic in one poorly worded post.

I COMPLETELY agree that this topic is like a secret joke played out on unsuspecting ignorant consumers, and will be posted and reposted over and over again, with the same results, but c'mon....

[tony176000]

Originally Posted by scrufy

Amazing.
Just read the article.
I give up.

http://www.state.mn.us/mn/externalDo...ctaneFacts.pdf

Ok, ok, I get it, you're trolling, right?

First, that's not an "article". Its a Q and A from some MN beauracracy. Thanks for the common sense BS that we all know already.

ANd second, you aren't driving the short bus, dude. You are riding in it...

[WinoGregorio]

Originally Posted by tony176000

Ok, ok, I get it, you're trolling, right?

First, that's not an "article". Its a Q and A from some MN beauracracy. Thanks for the common sense BS that we all know already.

ANd second, you aren't driving the short bus, dude. You are riding in it...

[iflyjetzzz]

Originally Posted by dday

So let's put this into real numbers, if you drive 12K miles/year and get an avg of 23mpg you'd save $11/month by using regular vs premium if you assume that premium is $.25 more per gallon.

If you can't afford $11/month you shouldn't be driving a BMW. That why every gas thread drives me nuts on here. An extra MPG or a few cents at the pump has little to no real effect on your wallet.

Just put in good gas and drive it like it was meant to be driven.

We compared mileage on my wife's Acura with midgrade vs premium. Premium is recommended. Premium was more cost effective ... the extra MPG more than offset the higher cost. The difference was >10% going from midgrade to premium.
I didn't bother experimenting with my 328i; I just use premium.

I would recommend anyone who's anal about it compare a month's MPG with regular vs a month's MPG with premium.

Originally Posted by TheRox

Riddle me this folks:

Lexus recommends premium in the IS350, GS350, ES350 etc

Don't these cars have basically the same V6 as the V6 Toyota Camry which does not require premium?

I did a cursory google check on compression ratios; it appears that the Camry has a lower compression ratio. So they're not exact same engines.

Originally Posted by Romanian nightmare

so here is another "myth" i've heard.... "Using ethanol free gas give you more mpg and is better for your engine"....

True on both counts. Ethanol has less BTU/gal than gasoline, resulting in lower MPG. Ethanol bonds easier with H2O than gasoline; water's not all that good for your engine. Those water molecules also dilute your gasohol, giving you even less MPG.

Originally Posted by scrufy

your research is a joke. sorry but they almost even put a hose in the same pool. they refine it to meet a government spec and thats it. from there on you could buy the cheapest crap or the best and guess what, your getting the same gas.

It's pretty embarassing to insult someone when you don't know what you're talking about. Yes, multiple brands of gasoline come from the same refinery or bulk terminal (after being moved by pipeline). It's all the same until it goes into the fuel tanker and additives are added.
The difference has to do with the additives. Not all companies' additives are the same. Sunoco and Chevron are good. Exxon sux.
Do some reading on the subject.

[WinoGregorio]

Originally Posted by iflyjetzzz

True on both counts. Ethanol has less BTU/gal than gasoline, resulting in lower MPG. Ethanol bonds easier with H2O than gasoline; water's not all that good for your engine. Those water molecules also dilute your gasohol, giving you even less MPG.

Yes on the first part. Ethanol has less BTU/gal than gasoline which requires more of it to make the same amount of power. Sort of correct on the next part. Ethanol is hygroscopic meaning that it attracts water from its surroundings. Not correct on the last part. Hygroscopy has proven to not be a big issue with E10 fuels as once was thought. It takes a long time and a lot of exposure to the atmosphere to get a measurable amount in the fuel. Granted, there are reports of increased water in fuel problems in some areas but these are mostly in marine and off road vehicles with vented fuel systems. Automobiles utilise a sealed system that prevents this problem.

[iflyjetzzz]

Originally Posted by WinoGregorio

Yes on the first part. Ethanol has less BTU/gal than gasoline which requires more of it to make the same amount of power. Sort of correct on the next part. Ethanol is hygroscopic meaning that it attracts water from its surroundings. Not correct on the last part. Hygroscopy has proven to not be a big issue with E10 fuels as once was thought. It takes a long time and a lot of exposure to the atmosphere to get a measurable amount in the fuel. Granted, there are reports of increased water in fuel problems in some areas but these are mostly in marine and off road vehicles with vented fuel systems. Automobiles utilise a sealed system that prevents this problem.

From what I've read, the problem of water gettting into gasoline is most likely to occur when the gas is in the gas station's underground tanks. Usually not enough to cause adverse effects on your car, but almost always not zero water.
As for the last part (Those water molecules also dilute your gasohol, giving you even less MPG.), any E10 that has water impurities in it will not get as good gas mileage as E10 with no water in it.
In the second part, we both said pretty much the same thing. "Ethanol bonds easier with H2O than gasoline" ~ "Ethanol is hygroscopic meaning that it attracts water from its surroundings."
It sounds like we're talking past each other quite a bit.

[WinoGregorio]

Yeah, the engineer in me means I have a tendency to pick nits sometimes!

[Bslaw83]

My fiance put regular in my car once and it ran like sh*t. Rough idle, rough starts, lagging performance. Y'all say it doesn't hurt the car, I have proof otherwise..stop being cheap and treat your car how it deserves to be treated

[Ink330]

Never realized Bimmer owners where such cheap f$#&! Maybe you shouldn't be driving your car if you can't afford to put the recommended gas in it. I can't afford to pay an extra .20-.30 per gallon for gas; but I see you'll sell me carbon fiber roundels for $2000...give me four! People have no problems dropping serious money on mods, but get their panties in a bunch when it comes to the gas they put in their cars. Yes, it's a big conspiracy that the manufacture recommends you put a certain type of gas in the car...how dare they!

[poiney]

Originally Posted by iflyjetzzz

We compared mileage on my wife's Acura with midgrade vs premium. Premium is recommended. Premium was more cost effective ... the extra MPG more than offset the higher cost. The difference was >10% going from midgrade to premium.
I didn't bother experimenting with my 328i; I just use premium.

.

IIRC, for Acura premium gas is "required" whereas for 328i, 87 octane is "required", so I'm not sure you can make the inference to the 328i. In fact, I've read multiple comments from BMW drivers who did the comparison and found that they couldn't tell any difference in MPG, which makes sense if the engine isn't being run that hard. I think you only see a difference if you run the engine hard.

[driverman]

Most of us love performance cars. BMW designed our cars with this mind, including the drivetrain, suspension, brakes, body structure, seats, required fuel, etc. Thousands of design decisions were made that result in a great car.

Some people that aren't into acceleration might want to save a few bucks on gas. Other people that aren't into handling might want to install soft tires to improve the ride. Not me. I want to enjoy the acceleration, handling and other attributes that BMW designed into the car and I'm willing to pay a premium for it.

[HpDellNestle]

Ok. Not respond to trolls that puke out what others told them.
I have data on average 3 months of using 91, now on to 89 for about 2 weeks. There is about 2 miles per gallon of difference. May not be worth it to go 89, but last 2 weeks have been snow and ice. Will finish 2 more months of 89 then down to 87. During dry days, for daily driving, really not seeing difference in "performance".
If in your daily drive, you need every last once of "performance" you can get from different oct, you are a road hazard.

[E92_328i_Boston]

The push to use more (20% instead of 10%) Ethanol in gasoline is causing corn commodity prices to skyrocket, thereby making everything made from corn more expensive for consumers. Not to mention, the process of creating ethanol for gasoline from corn uses more energy than you gain in the end. In other words, it's totally inefficient. Finally, it's not good for engines for a bunch of reasons. Look it up.

Start to think about these issues when you vote.

[Saintor]

Originally Posted by HpDellNestle

I have data on average 3 months of using 91, now on to 89 for about 2 weeks. There is about 2 miles per gallon of difference.

10% difference ? No f* way. And if you stand by this, your credibility is zilched.

[John 070]

Originally Posted by Saintor

10% difference ? No f* way. And if you stand by this, your credibility is zilched.

Totally agree. He flunked stats as far as reliability goes when it comes to his data. 3 mos. of data on 91, and 2 weeks on 89. 2 mpg difference.

The "premium gets better mileage than regular" myth has been busted so many times it's not even funny.

Again, I'd say, we drive BMW's, not a big deal, let's all use premium whether a 328 or 335. But don't make false claims as to the benefits of premium.

[John 070]

Originally Posted by WinoGregorio

hygroscopic meaning that it attracts water from its surroundings.

I believe that brake fluid has the above property, in that it loves water. That's the only time I've ever heard the word used.

[WinoGregorio]

Originally Posted by John 070

I believe that brake fluid has the above property, in that it loves water. That's the only time I've ever heard the word used.

Ah yes but don't forget that DOT 5 brake fluid is Hydrophobic!

[John 070]

Originally Posted by WinoGregorio

Ah yes but don't forget that DOT 5 brake fluid is Hydrophobic!

Interesting, is that what's used now? I know my 335's had its brake fluid changed 2X in 4 yrs....

[WinoGregorio]

Originally Posted by John 070

Interesting, is that what's used now? I know my 335's had its brake fluid changed 2X in 4 yrs....

No, still DOT 4 from factory. That is still the best for all street and most track applications.

[ChasVS]

Originally Posted by scrufy

Amazing.
Just read the article.
I give up.

http://www.state.mn.us/mn/externalDo...ctaneFacts.pdf

Try this, it makes sense and explains why a high performance engine needs a higher octane rated fuel.


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.

[WinoGregorio]

I like your line of reasoning but be careful how you oversimplify concepts or someone might point out that high performance turbo or supercharged engines are typically very low compression yet still require high octane fuel. Dynamic Compression and Effective Pressure are better indicators but hard to obtain accurately from any published data.

Sorry, the engineer in me again! D

Now, to confuse things even more. Why not? It's fun!
The 335 is not like other turbocharged engines in that it has a very high static compression ratio. Direct Injection allows for much higher cylinder pressures and temperatures because there is no fuel in the cylinder during most of the compression stroke. Only at the moment right before ignition is fuel present in the chamber.

[WinoGregorio]

BTW, I came across this dyno test in an old Hot Rod magazine. Here it is online
http://www.hotrod.com/techarticles/f...son/index.html

The most important take away is what I have been saying all along - high octane fuels do NOT necessarily burn slower that low octane.

"But most of all, we discovered that our presumption that higher-octane fuels burn slower than lower-octane fuels (and therefore require more ignition lead) is largely incorrect."