[Motorsport_235i]

Do you guys put 91 or 94 octane for the M235i?
i usually put 91 cause here in canada gas is expensive like 1.40 per liters at 1.94

[Beartato]

It's in your manual.

[wjones14]

http://www.2addicts.com/forums/showthread.php?t=1319123

[petegtsv10]

Originally Posted by Beartato

It's in your manual.

I doubt that the answer to the OP's question is in his manual....he wants to know what octane owners use, not what is recommended by BMW.

[crabu2]

BMW says to run 89 minimum, but 91 is recommended.

My understanding is that BMW tunes the engine to run on 91 oct. If you run lower, the knock sensor will retard the timing to prevent damage, but you do lose a bit of HP. If you use more than 91, it shouldn't give you more HP because it's supposedly tuned for 91.

Basically, run what you want, but unless you're running a tune, anything over 91 is a waste.

BTW, I know 2 people that run 87.. They're both daily drivers and they say they can't tell the difference in performance between 87 or 93 octane gas. I told them they're timing is retarded so they're making less power and they might get startup knocking. Still, they both say they can't tell a power difference and they've never heard any knocking.. One is on his 2nd BMW and says he's always run 87, unless he finds premium at a discount ... usually only gets Premium at Costco since it's cheap enough there. Before BMW he had Acura.. He said he's always run 87 in his Acuras too.

[pz619]

I use 91 octane, mainly because that's pretty much the best you can get in California.

[XutvJet]

It's a turbo car. Run the highest octane you can for maximum performance. I run 93. I'm not saying 93 will make more power than 91, but the power will tend to be more consistent with 93 when the intake charge is hot, the intercooler is heat soaked, and/or ambient conditions are hot and humid. Higher octanes (within reason) will do a better job of managing knock/pre-detonation potential, therefore more consistent power and less power pull back.

[crabu2]

Originally Posted by XutvJet

It's a turbo car. Run the highest octane you can for maximum performance. I run 93. I'm not saying 93 will make more power than 91, but the power will tend to be more consistent with 93 when the intake charge is hot, the intercooler is heat soaked, and/or ambient conditions are hot and humid. Higher octanes (within reason) will do a better job of managing knock/pre-detonation potential, therefore more consistent power and less power pull back.

What you're saying makes absolute sense, but is anyone going to be able to tell a difference between say more consistent power versus making 10 or even 20 hp less?

I can see the difference on a track or the strip, but most people ... just drive on roads won't know the difference.. I highly doubt anyone can tell on their day to day driving.

Me.. I'll use the minimum required, unless I hear knocking or I'm going to the track... which I haven't done in decades.

[Rayscott]

91 here for the 228 and 89 for the X3. No issues. Why pay more for everyday driving.

[Dylan86]

Ethanol Free 94, or Shell V-Power. Otherwise any 91 when I can't get some 94 or Shell V-Power action..

I get all of my satisfaction back by putting nothing BUT 87 octane in my commuter truck, lol..

D

[XutvJet]

Originally Posted by crabu2

What you're saying makes absolute sense, but is anyone going to be able to tell a difference between say more consistent power versus making 10 or even 20 hp less?

I can see the difference on a track or the strip, but most people ... just drive on roads won't know the difference.. I highly doubt anyone can tell on their day to day driving.

Me.. I'll use the minimum required, unless I hear knocking or I'm going to the track... which I haven't done in decades.

You won't hear the knocking/pinging. The DME and the knock control systems are too quick and smart. Timing gets pulled, boost reduced, and fuel added. The DME then tries to adjust back to meet maximum torque values.

93 in Kansas City is no more expensive than 91. You probably won't notice much difference in sub 70 degree temps, but in warmer/humid climates, you may notice a difference in response and topend power. There are many dynos floating around out there of N54 and N55 motors comparing 91 vs 93 octane runs. Now granted most of the cars measured had at least tunes, it's very clear that there is real measurable difference in power between 91 and 93. Usually in the order of 10-15 whp/wtq. Remember, these cars are underrated by BMW so the car might make just above advertised power with 91 and with 93, a bit more.

[khaug]

Our 2015 M235 seems utterly happy on a diet of Shell mid-grade, which is 89 octane. As does our 2016 X3 35i (essentially the same engine).

That said, I'd switch to the best stuff available for track time or long trips in hot weather.

-K.

[omera60]

I use Shell V-Power Nitro+ Unleaded which I believe is 97 and it runs like a baby. Bear in mind mine is a 3 Cylinder Engine.

[Beartato]

Originally Posted by petegtsv10

I doubt that the answer to the OP's question is in his manual....he wants to know what octane owners use, not what is recommended by BMW.

Doesn't matter...the recommended octane is all you need unless you have a specific set up that requires a higher octane fuel. Otherwise you're just wasting your money.

[crabu2]

Originally Posted by omera60

I use Shell V-Power Nitro+ Unleaded which I believe is 97 and it runs like a baby. Bear in mind mine is a 3 Cylinder Engine.

Isn't that a RON rating and not an AKI rating, like we use in the States?

[omera60]

Originally Posted by crabu2

Isn't that a RON rating and not an AKI rating, like we use in the States?

Yeah, it's RON rating. I have never heared of the AKI rating, what exactly is it?

[crabu2]

Originally Posted by omera60

Yeah, it's RON rating. I have never heared of the AKI rating, what exactly is it?

Here in the States we use AKI for the octane rating.. It stands for Anti Knock Index.

https://en.wikipedia.org/wiki/Octane_rating