Last post on Apr 27, 2007 at 10:13 PM
You are in the BMW X3 & X5
What is this discussion about?
#41 of 76 Re: Questions? [markcincinnati]
Jan 04, 2007 (1:59 pm)
The words BMW chooses to use are significant. There is a difference between "recommend" and "require," and BMW's engineers and lawyers are smart enough to understand that difference. So when they write in the 2006 X3 Driver's Reference Guide that the use of 91 octane is "recommended" you should take that at face value.
BMW -- like many companies -- tends to go WAY overboard in providing warnings in its product material so it doesn't have to deal with unhappy customers. The X3 manual even warns owners: "Do not remove the covers [of the LED's], and never stare into the unfiltered light for several hours, as irritation of the retina could result."
Now, Mark, in the real world, which do you think would be the more likely problem? Owners filling up with 87 octane -- which you suggest will cause engine damage -- and insisting on expensive replacements under warranty? Or owners disassembling their dashboards and staring "into the unfiltered light for "several hours"?
You are certainly entitled to your opinion, Mark, but reasonable people will appreciate that that BMW's engineers and lawyers know their product better than you do. Bottom line, THEY don't "require" the use of premium unleaded fuel.
And if you want yet more 'expert' opinion, consider what the service manager of one of the east coast's largest Mercedes dealerships told the Washington Post back not too long ago:
"It's not going to hurt anything," said Peter Gregori, service manager for EuroMotorcars, a Mercedes-Benz dealer in Bethesda. In fact, Gregori has been using regular gas in one of his own Mercedes cars for two years, and "it's perfect," he said .... Among cars that come in for service, Gregori said, he can't tell which have been sipping premium."
And the article concluded:
"Automotive experts say using regular gas in most vehicles does no damage and makes no discernible difference in performance. Cars made in the past 15 years have such highly refined computer controls that the engine will adjust to the grade of octane in the gasoline, even in cars sold as requiring premium gasoline. Some drivers -- in some cars under some driving conditions -- may notice a drop in horsepower, but for most people behind the wheel, it wouldn't be enough to notice, the experts say."
And, finally, Mark, take a deep breath, because no one but you has suggested that the "recommendation" that drivers use premium is, as you put it in your post, an "elaborate lie."
The use of 91 octane fuel permits manufacturers to achieve and, more importantly, report in brochures, higher peak horsepower and peak torque numbers, which matters ENORMOUSLY in marketing.
Take a look for example, at the footnotes in the performance specifications on the Lexus website for any sedan. "Ratings achieved using the required premium unleaded gasoline with an octane rating of 91 or higher. If premium fuel is not used, performance will decrease."
#42 of 76 Re: Questions? [jrynn]
Jan 05, 2007 (12:05 pm)
I generally agree but still use premium if it's recommended. On the otherhand, if your car is designed to run on 87 octane, you could damange the car by using premium.
#43 of 76 Re: Questions? [davidc1]
Jan 05, 2007 (3:44 pm)
"On the otherhand, if your car is designed to run on 87 octane, you could damange the car by using premium."
#44 of 76 Re: Questions? [bodble2]
by Stever@Edmunds HOST
Jan 05, 2007 (5:13 pm)
Try a search for "detonation" or "premium" for posts like this one that discuss some of the various problems that running premium in a car tuned for regular gas can cause:
shipo, "What about fuel types & gas mileage?" #228, 9 May 2006 5:36 pm
It is funny you never see "regular gas required" in the manuals.
Skip back up about 10 posts above the one linked for the start of that thread, including Shifty's great quote that there's a "common misconception that premium fuel is some kind of "doggie treat" for your car."
#45 of 76 Re: Questions? [bodble2]
Jan 05, 2007 (7:54 pm)
This is based on my belief that modern cars designed to run best on higher octane fuel have built in knock sensors that will retard the ignition timing. But cars designed to run on regular do not have a mechanism to advance the timing in the event that higher octane is used. What would they use to sense the higher octane when there's no knocking? It was explained to me by a service manager many years ago that higher octane doesn't mean higher energy. Lower octane actually burns faster. Slow burning fuel used in engines setup for faster burning fuel sounds like trouble in the long run. Not that we are talking about a major damage.
#46 of 76 Re: Questions? [davidc1]
Jan 07, 2007 (5:44 pm)
If the mfgr offers a vehicle that can run without damage on Regular but will improve its Power and MPG's with Premium, why not spell it out that way?
The new 2007 Chrysler 300 specifies MID grade and says, essentially, don't waste your money on Premium. The words used include what amounts to a suggestion that "while using regular is OK, "optimum" performance is realized with mid grade."
Several of my Audis actually rated power and mileage on the octane. This provided the data points to determine the validity of the phrase "false economy."
Lawyers, probably, determine the wording used, hence the word REQUIRED is seldom used unless it has been determined that warranty claims will offset the law suits or better said potential law suits.
I found several (more than two) websites that had as their number one "rule" -- "follow the mfgr's recommendation."
I found many (more than five) websites that did claim using Regular in a car designed for Premium would NOT technically damage the engine, but several of these did hint at the loss of power and reduced MPG's that go hand in hand with this practice.
In the spirit of full disclosure, I could not find any data that said the full amount of the price difference was consumed by the loss of power and reduced miles per gallon such behavior engenders.
Yet, virtually all of the data says the main reason a car is said to have premium fuel recommended is that it has a compression ratio that will lead to pre-ignition (which is harmful) -- and that the ping is controlled by retarding the spark, meaning the spark happens earlier in the compression cycle, increasing pollution and decreasing mileage AND performance.
Apparently the advent of electronic controls have offset pre-ignition's potential damage. But the issue that this causes is lower power than "one was used to" and what happens (or probably happens) is one's right foot presses further downward exacerbating this reduction in both pre-ignition and power.
It would be my "request" for the mfgs to explicitly define power and mpg consequences of using regular, mid-grade and premium and let us all decide.
In the mean time, without sufficient information, I would urge all drivers to "do what the manual" says (regardless of the "r" word -- require or recommend, that is.)
The authors who appear to understand the physics and the chemistry say "you can use regular, but -- here are the consequences." At twenty gallons per week per car the difference in cost per gallon is $200 per year, the difference in opportunity cost appears to be less than that; and, some argue is a negative number.
There appears to be a "secret handshake" we are all (or at least some of us) looking for and that is, you can buy a BMW or an Audi and despite the mfg's recommendations use regular gas without any consequences.
If this is really true, I would imagine once enough of us figure it out, there will be at least the hint of a class action, so we "won't get fooled again."
I suspect there is something to it more than "ego" -- for this kind of false requirement would, once it got out, also be cause for customer retailiation. At $200 per year per car, since 1973 (the year I had to buy my own gas), hmm, let's see, 34 years $200 per year approximately, carry the five -- well that's $6400 that someone owes me.
#47 of 76 Re: Questions? [markcincinnati]
Jan 08, 2007 (7:00 am)
True that. Can't hurt to follow mfgr's recommendation. Re: spark timing, retarded ignition means spark happens later, not earlier, more like when the piston reaches TDC (top dead center).
#48 of 76 Re: Questions? [davidc1]
Jan 11, 2007 (5:05 am)
I stand corrected, I got carried away.
#49 of 76 Twin turbo in X3?
Jan 11, 2007 (6:41 am)
Do you think BMW will one day put the 3.0 twin turbo engine in the X3? I would think that would do a lot to distance the X3 from the evolving competition.
In addition to the 3 series, BWM has announced this engine will now be available in the new 5 series AWD as the 535Xi.
#50 of 76 Re: Twin turbo in X3? [bruceomega]
Jan 11, 2007 (6:56 am)
I can't help but wonder if BMW + not 1 but 2 turbos = reliability nightmares?