[dudical26]

Hello, does anyone have experience using 87 octane in an x5?

I’ve got a 2020 x3 xdrive 30i and I’ve done 16k miles with 87 octane. I know the manual suggests higher octane but clearly the ecu is compensating just fine. I’m sure peak power is down slightly but I also think it’s pretty clear I’m not experiencing catastrophic knock if I’ve done this mileage. I drive normal, sometimes easy, sometimes I floor it.

I’ve got a new x5 40i coming, wondering what experience anyone has using 87 octant.

Please don’t post unless you’ve got hands on experience. I’m already aware of what the manual says, and also understand some of you will say this is a premium car and needs premium gas. I’d like to just hear real world experience please

Thanks!

[TurtleBoy]

Originally Posted by dudical26

Hello, does anyone have experience using 87 octane in an x5?

I’ve got a 2020 x3 xdrive 30i and I’ve done 16k miles with 87 octane. I know the manual suggests higher octane but clearly the ecu is compensating just fine. I’m sure peak power is down slightly but I also think it’s pretty clear I’m not experiencing catastrophic knock if I’ve done this mileage. I drive normal, sometimes easy, sometimes I floor it.

I’ve got a new x5 40i coming, wondering what experience anyone has using 87 octant.

Please don’t post unless you’ve got hands on experience. I’m already aware of what the manual says, and also understand some of you will say this is a premium car and needs premium gas. I’d like to just hear real world experience please

Thanks!

I don't think you are. For MY24 the recommended minimum Octane was changed to 87 so you should be fine.



PS. It is a premium vehicle so sort of seems foolish to try and save a few bucks and not give it premium. Sorry - had to say it.

[dudical26]

Oo that’s cool. Glad they reduced it.
Thanks for sharing.

[jad03060]

Note, the engine tuning in the MY23 is different from those previous, so it is not necessarily correct to assume what works for a newer engine version is suitable for an older model.

[slicky]

Well, yes the ecu will compensate, but how? The engine needs to start knocking before it pulls timing. That bit of knocking just a bit does just a bit of damage. A little damage on constant basis probably isn't very healthy for the engine. It probably feels fine but probably has sustained more wear than normal for the mileage.

[eelnoraa]

Originally Posted by slicky

Well, yes the ecu will compensate, but how? The engine needs to start knocking before it pulls timing. That bit of knocking just a bit does just a bit of damage. A little damage on constant basis probably isn't very healthy for the engine. It probably feels fine but probably has sustained more wear than normal for the mileage.

Knocking by using too low of octane don’t start immediately become pre-ignition detonation, the bad kind of knocking. In fact, for pre LCI b58, there is no gasoline in the compression stroke, nothing to ignite. Knocking usually starts by having local detonations in the power stroke after spark plug fire. Think small detonation started away from the main spark, create a “ping” sound. It is also call pinging. It isn’t great but not nearly as bad as the pre-ignition kind. Knock sensor basically is like a microphone listening to the ping and restart timing for intake stroke, let out some air, reduce compression. It happens very quickly as soon as the first ping is detected. It does not causing any damage at that level. You do lose some performance for sure. But I am with you guys here, just why?? It is not like 91 is significantly more expansive. It is usually about 6-7% higher. Average American drive 12-15k mile per year. Annual saving is like $100, hardly worth the effort or mental stress.

[mmm50i]

Originally Posted by TurtleBoy

I don't think you are. For MY24 the recommended minimum Octane was changed to 87 so you should be fine.

Attachment 3230298

PS. It is a premium vehicle so sort of seems foolish to try and save a few bucks and not give it premium. Sorry - had to say it.

I just checked my manual, I did not know BMW recommends 93 octane for M Performance models

[Marty in NY]

Originally Posted by eelnoraa

It is not like 91 is significantly more expansive. It is usually about 6-7% higher. Average American drive 12-15k mile per year. Annual saving is like $100, hardly worth the effort or mental stress.

Right, I figured with the price diff between 89 and 91 it'll cost me less than $300/yr in gas to stick with 91. It's funny, we spend $80K on a car and then try to save a nickel on gas. I recall this same calculation when my wife and I wanted to buy a diesel. Sure diesel cost more/gallon than gas but gets much better miles per gallon economy. However, you have to also factor in the added price of the diesel car so in the end, it was pretty much a wash when keeping it for 7-8 yrs. (we loved it, we called it the tractor due to how it sounded :-)
BMW's are known for their perky performance, virtually no turbo lag like an Audi and the transmissions are excellent....why downgrade all that you paid for just to think you're saving a ton of money by putting cheaper gas in the tank? That dog don't hunt.

[Giggler]

I just looked in the manual and verified myself, had no idea they would recommend anything less than 91. Is that because the LCI is doing miller cycle which optimizes combustion? It sounds like the OP can do it if he wants but I’m sure it would cut power. I’m fortunate enough to have a Costco nearby that sells premium gas for like 80c cheaper vs the local chevron.

[TurtleBoy]

Originally Posted by Giggler

I just looked in the manual and verified myself, had no idea they would recommend anything less than 91. Is that because the LCI is doing miller cycle which optimizes combustion? It sounds like the OP can do it if he wants but I’m sure it would cut power. I’m fortunate enough to have a Costco nearby that sells premium gas for like 80c cheaper vs the local chevron.

I don't think the reason for the change has been made public. For th pre-LCI the minimum was 89.

[aaaaaaaaaz]

You'll be fine. Many rental cars or loaner car might have not see a drop of premium gas during its service life... Manufacture knows there always be some people putting regular gas in car asking for premium for whatever reason...

Saying about MY24, yes - manual says minimum 87. The car must be fine running on 87, otherwise BMW could be liable if gas is indeed causing issue. It even stated that this has no effect on engine life, so you can definitely use 87 safely without concerning if it will damage the car.

I did put half a tank of 87 in my 21 x3 m40i (which ask for 89min) a while ago during a roadtrip where 91 was somehow soldout. Did not feel much difference - but maybe the MPG seems a bit lower (21 vs 22 on highway 85mph?)

[jad03060]

Because the computer must detune the combustion process to keep from damaging itself when you choose a lower octane fuel, it is to be expected that performance and efficiency can go down. Whether you notice it or not will depend on if you actually try to stress things. Most people don't regularly stress their vehicle's performance.

[aaaaaaaaaz]

Originally Posted by jad03060

Because the computer must detune the combustion process to keep from damaging itself when you choose a lower octane fuel, it is to be expected that performance and efficiency can go down. Whether you notice it or not will depend on if you actually try to stress things. Most people don't regularly stress their vehicle's performance.

I think performance definitely favors the higher octane fuel, but efficiency might be case by case
Car and driver did a test on 91(required) vs 93(recommended) on M5C. 91 actually got 0.7mpg better than 93.
https://www.caranddriver.com/feature...dodge-charger/

In X5 case, 87(required) vs 91(recommended) I doubt anyone have done a test yet, but I bet 91 would see slightly more hp, but efficiency should not differ by too much

[jad03060]

If 93 octane induces you to use maximum performance, yes, it is quite reasonable that you'd get better efficiency with a lower octane fuel.

[aaaaaaaaaz]

Originally Posted by jad03060

If 93 octane induces you to use maximum performance, yes, it is quite reasonable that you'd get better efficiency with a lower octane fuel.

Car and driver measure efficiency at 75mph highway test. Induced tendency of driving more aggressively is simply irrelevant.

[eelnoraa]

I don’t think efficiency is the difference. If anything it is peak HP and torque. After all, the trick is delay intake stroke timing, let call intake valve open long we well into compression stroke, less air, less compression, no knocking. Less air, less fuel injected, less power.

[aaaaaaaaaz]

Originally Posted by eelnoraa

I don’t think efficiency is the difference. If anything it is peak HP and torque. After all, the trick is delay intake stroke timing, let call intake valve open long we well into compression stroke, less air, less compression, no knocking. Less air, less fuel injected, less power.

Yup. However the surprising result is - M5C with 91 made more torque than 93 somehow. It might be noise statistically, but that also suggest the actual difference is quite small for both hp and torque.

[eelnoraa]

Originally Posted by alanzyy

Yup. However the surprising result is - M5C with 91 made more torque than 93 somehow. It might be noise statistically, but that also suggest the actual difference is quite small for both hp and torque.

Seems like a measurement noise. One has higher torque and lower HP. The other test has lower torque and higher HP. This cannot be true. After all HP = torque x rpm x constant. Give the same engine, rpm and the constant are the same. So HP vs torque should be linear relationship. Bit either way, no one can feel the 10hp difference in a 600hp car.

[nZtiZia]

Originally Posted by Giggler

I just looked in the manual and verified myself, had no idea they would recommend anything less than 91. Is that because the LCI is doing miller cycle which optimizes combustion? It sounds like the OP can do it if he wants but I’m sure it would cut power. I’m fortunate enough to have a Costco nearby that sells premium gas for like 80c cheaper vs the local chevron.

the language is actually clear.

“recommended” is what they recommend. that is clear.

“minimum” is the absolute minimum if you can’t get higher octane.

[Bmwx5z]

Originally Posted by TurtleBoy

I don't think you are. For MY24 the recommended minimum Octane was changed to 87 so you should be fine.

Attachment 3230298

PS. It is a premium vehicle so sort of seems foolish to try and save a few bucks and not give it premium. Sorry - had to say it.

How come there is a discrepancy between what’s in the manual and what’s written in the fuel door Min 89

[TurtleBoy]

Originally Posted by Bmwx5z

How come there is a discrepancy between what’s in the manual and what’s written in the fuel door Min 89

Using old stickers I would guess.

[jad03060]

What is potentially confusing is that depending on where in the world you are, the way that octane is measured uses different scales.