What grade gas you running in 3.0's

[mfullmer]

First. The X5, or any vehicle that doesn't have a super/turbo charger is made to run on 87 octane fuel. There are many places in the world, where BMW and other premium manufacturers sell vehicles, where 87 is the only fuel available. The advanced engine management computer is designed to adapt to different octane levels (That's straight from BMW literature.)

And I would love to know where someone got the notion that running less than 91 octane would "damage" the engine, pistons, etc. That is just rubbish. A properly tuned X5 engine will not knock using any standard grade of fuel. There is no damage, no warranty issue, no wear/tear (other than normal) issues. That is just ignorant thinking.

According to BMW the reason they RECOMMEND (You'll not see or hear anyone at BMW say REQUIRED) Premium fuel is that you do reap a 1 -2% power increase. Therefore, they can publish numbers using Premium. There is not other advantage, mileage, wear, etc advantage to using premium fuel. In fact, one of the BMW engineers says he has tried several times changing back and forth and trying to "feel" the power difference but can't. Let's face it people, without your mind telling you, do you really think you can feel the difference of 4-5 bhp?

Originally Posted by x54.4blue

I don't get it, a BMW X5 is a $50,000 car/truck, it is made to run one 91 and you want to save five dollars by using cheaper gas?

Don’t be penny wise and pound foolish

[crosvs]

Even on 91, however, my car has always demonsrtated a LITTLE bit of knock if I put a lot of load on it at LOW RPM. I checked with hte dealer and they sad that's normal.

Out of curiosity, I once hit up the 76 station in Brentwood (the one on San Vicente) and filled my X full of yummy 100 octane fuel ... ZERO knock *EVER*

[DINANM3]

Put premium gas in your Bimmers its not worth it. The knock sensor is there to save your ass if you cant get any good gas in a pinch. Its not meant to be used day in day out for 100,000 miles.

Plus if you need the extra 5 bucks from a fill up that bad. then you really cant afford a Bimmer anyway.

[lionkang]

I've used 87 in nearly every tank for 2 years and 40k miles. No knocks ever and with 93 a very very minute difference in power.

[mfullmer]

What? The ECU ("knock sensor") isn't concerned about what kind of gas you put in your vehicle. This is a sophisticated computer that constantly monitors the engine and adjust certain computerized/electronic actions within the engine. The computer is ON and ACTING 100% of the time the vehicle is running. Whether it adusts a lot or a little doesn't have any effect on it.

It's just like the CPU of any computer. You can run it 24 hours a day under 100% load or 1 hour a day under 5% load. The CPU is not going to go out or be damaged in any way - it's not a mechanical device that wears.

Jees, we use petrol every day, we drive every day yet so many "enthusiasts" haven't the first clue on how modern engines work. We aren't dealing with a '68 Corvette here, people.

Originally Posted by DINANM3

Put premium gas in your Bimmers its not worth it. The knock sensor is there to save your ass if you cant get any good gas in a pinch. Its not meant to be used day in day out for 100,000 miles.

Plus if you need the extra 5 bucks from a fill up that bad. then you really cant afford a Bimmer anyway.

[SANguru]

copy and paste from my response to you in the lounge. Go out there and try it out yourself...

you just contradicted yourself in your last post. "Monitor and adjust." You can't monitor something that hasn't happened yet can you? ECU cannot read fuel quality. You get preignition, ECU adjusts, dials back timing.. lose power. Of course you're more proned with forced induction motors. By the way, I highly recommend that you play with your hidden on board diagnostics on your OBC. EGT temp and 02 sensor reading goes up BEFORE the timing dials back. If that doesn't prove against your case to each their own, it's your car, not mine. But here's how you can get into it. Can remember of the top of my head which option it is but it's in there..


UNLOCK PROCEDURE:

1) Key to ignition pos 2 (no need to start engine).
2) Fasten the seat belt to get rid of the "Fasten Seat Belt" message.
3) Press the right button on the instrument panel, and hold it until "TEST-NR. 01" comes up (5 to 10 seconds).
4) Press the left button on the instrument panel, and the vehicle id comes up (last 7 digits of VIN).
5) Add up the last 5 digits to get the "unlock code", e.g. the unlock code for "AB12345" would be 15 (1+2+3+4+5).
6) Repeatedly press the right button until "TEST-NR. 19" appears.
7) Press left button -> "LOCK : ON"
8) Repeatedly press left button until "LOCK : xx" appears, where "xx" is your unlock code.
9. Press the right button. All modes are unlocked now.

NAVIGATING BETWEEN TESTS AND PERFORMING THEM:

- Follow steps 1) to 3) of the "UNLOCK PROCEDURE" to enter test mode.
- Use the right button to step from test to test.
- Press the left button to enter a test and cycle between modes within a test.
- Press and hold the right button to exit test mode (turning the key to 0 works as well).

Originally Posted by mfullmer

What? The ECU ("knock sensor") isn't concerned about what kind of gas you put in your vehicle. This is a sophisticated computer that constantly monitors the engine and adjust certain computerized/electronic actions within the engine. The computer is ON and ACTING 100% of the time the vehicle is running. Whether it adusts a lot or a little doesn't have any effect on it.

It's just like the CPU of any computer. You can run it 24 hours a day under 100% load or 1 hour a day under 5% load. The CPU is not going to go out or be damaged in any way - it's not a mechanical device that wears.

Jees, we use petrol every day, we drive every day yet so many "enthusiasts" haven't the first clue on how modern engines work. We aren't dealing with a '68 Corvette here, people.

[Quicksilver]

I would like to see the literature to back up your statements. Would you please provide that information please. Especially the part that reads "The advanced engine management computer is designed to adapt to different octane levels" (That's straight from BMW literature.) Thanks

Originally Posted by mfullmer

First. The X5, or any vehicle that doesn't have a super/turbo charger is made to run on 87 octane fuel. There are many places in the world, where BMW and other premium manufacturers sell vehicles, where 87 is the only fuel available. The advanced engine management computer is designed to adapt to different octane levels (That's straight from BMW literature.)

And I would love to know where someone got the notion that running less than 91 octane would "damage" the engine, pistons, etc. That is just rubbish. A properly tuned X5 engine will not knock using any standard grade of fuel. There is no damage, no warranty issue, no wear/tear (other than normal) issues. That is just ignorant thinking.

According to BMW the reason they RECOMMEND (You'll not see or hear anyone at BMW say REQUIRED) Premium fuel is that you do reap a 1 -2% power increase. Therefore, they can publish numbers using Premium. There is not other advantage, mileage, wear, etc advantage to using premium fuel. In fact, one of the BMW engineers says he has tried several times changing back and forth and trying to "feel" the power difference but can't. Let's face it people, without your mind telling you, do you really think you can feel the difference of 4-5 bhp?

[Quicksilver]

While your at it please provide any printed information that will verify that "According to BMW the reason they RECOMMEND (You'll not see or hear anyone at BMW say REQUIRED) Premium fuel is that you do reap a 1 -2% power increase. Therefore, they can publish numbers using Premium. There is not other advantage, mileage, wear, etc advantage to using premium fuel. In fact, one of the BMW engineers says he has tried several times changing back and forth and trying to "feel" the power difference but can't."

Not that I don't believe you but certinally we would all benefit from looking over the paper work citing your conclusions. Thanks again.

[DINANM3]

Originally Posted by mfullmer

What? The ECU ("knock sensor") isn't concerned about what kind of gas you put in your vehicle. This is a sophisticated computer that constantly monitors the engine and adjust certain computerized/electronic actions within the engine. The computer is ON and ACTING 100% of the time the vehicle is running. Whether it adusts a lot or a little doesn't have any effect on it.

It's just like the CPU of any computer. You can run it 24 hours a day under 100% load or 1 hour a day under 5% load. The CPU is not going to go out or be damaged in any way - it's not a mechanical device that wears.

Jees, we use petrol every day, we drive every day yet so many "enthusiasts" haven't the first clue on how modern engines work. We aren't dealing with a '68 Corvette here, people.

You really are an idiot. Im not saying your computer will get burnt out because it is being used. I am saying that the computer has to wait for a knock or detonation to happen first before it fixes the problem. Now if it is knocking or detonating daily and you computer will adjust before the damn thing blows up. Thats fine. Your motor will be fine today. But how will the top off your pistons look after 100,000 miles of that happening

[Jiga jace1]

I Use 93... Is That A Good Thing Or Should I Be Getting 91?