Octane

[Stock4Evr]

2012, 135i - Normal, mostly highway, driving. I fill up with Shell 93 Octane. I think I can go with 89 Octane. What are your opinions?

[Esteban]

According to page 113 of my owners manual: AKI 91 is highly recommended, but you can use gas with less AKI. The minimum AKI rating for the 135i is 89.

[SkullV]

The ECU will adapt but the drop in gas mileage will cancel out savings at the pump. Might as well just stick with the 93 for better performance. The additive package in the "premium" fuel is usually better too, but I believe all of Shells gas is "Top-tier".

[heist_tub]

If you can afford the car you can afford the gas. If not get a different car as a DD. Premium is cheaper than a new car/engine.

[Esteban]

Would use 93 but no gas stations close to me sell it. I use Chevron 91.

[SkullV]

Originally Posted by Esteban

Would use 93 but no gas stations close to me sell it. I use Chevron 91.

I also use 91. We have the same stupid gas here as you do in California. You can mix some E85 in for an octane bump but the car does fine on 91.

[Esteban]

Originally Posted by SkullV

I also use 91. We have the same stupid gas here as you do in California. You can mix some E85 in for an octane bump but the car does fine on 91.

I agree that 91 is fine but we could always use a little more octane in our lives.

Don't feel like mixing though.

[kprocivic]

I been mixing for a good year now. It sucks but I'm used to it. 100 with 91.

[david in germany]

Originally Posted by Esteban

I agree that 91 is fine but we could always use a little more octane in our lives.

Don't feel like mixing though.

If you believe this than you really don't onderstand the concept of octane.
You should run the lowest octane your car is rated for ( the exception is cars running a tune with the need of a higher octane than the manufacturer recommends)

Using my non turbo 118i as an example.
Until Germany introduced E5 super I would regularly use E0 91 octane in my e87 and average 36-37 mpg showing my car is running efficiently. They have since added (mandated) E5 as super and you can only find Super plus (95 octane) without ethanol. I have been rewarded with a drop to 33-34 mpg since the change. The lower the octane the more volatile the fuel is (lower detonation point) Higher octane is more resistant to detonation. Non tuned cars can make more power on lower octane fuels.
Boosted cars are another ball game.
If you are not highly tuned (including bmw ppk)stick with 91.
Big tune, run a 93-95 or what the tuner recommends.

[Esteban]

Originally Posted by david in germany

If you believe this than you really don't onderstand the concept of octane.
You should run the lowest octane your car is rated for ( the exception is cars running a tune with the need of a higher octane than the manufacturer recommends)

Using my non turbo 118i as an example.
Until Germany introduced E5 super I would regularly use E0 91 octane in my e87 and average 36-37 mpg showing my car is running efficiently. They have since added (mandated) E5 as super and you can only find Super plus (95 octane) without ethanol. I have been rewarded with a drop to 33-34 mpg since the change. The lower the octane the more volatile the fuel is (lower detonation point) Higher octane is more resistant to detonation. Non tuned cars can make more power on lower octane fuels.
Boosted cars are another ball game.
If you are not highly tuned (including bmw ppk)stick with 91.
Big tune, run a 93-95 or what the tuner recommends.

I'm sure I don't understand the concept of octane, but see the smiling face in my post above? It means I'm having some fun.

I do have a tune, It's not super-powerful or anything, but still a tune. check my sig.

BTW, thanks for edumacating me.

[Esteban]

It looks like Dinan uses 93 octane when testing Stage 2 software, so I guess I could use a little more octane in my life.

[Dackelone]

Mail order...

try using their search engine for a gas station near you...
http://www.vpracingfuels.com/vp-100-fuel

[SkullV]

Originally Posted by Esteban

It looks like Dinan uses 93 octane when testing Stage 2 software, so I guess I could use a little more octane in my life.

I would be shocked if your butt dyno could discern a difference between 91 and 93, especially on a canned tune like the Dinan software. Tuners will always advertise their results on the highest commonly available grade of fuel. It will always yield the highest numbers, even if those numbers are only a couple digits off.

[Esteban]

Originally Posted by SkullV

I would be shocked if your butt dyno could discern a difference between 91 and 93, especially on a canned tune like the Dinan software. Tuners will always advertise their results on the highest commonly available grade of fuel. It will always yield the highest numbers, even if those numbers are only a couple digits off.

It doesn't really matter because there isn't 93 around me anyway. Thought it was interesting that Dinan, which is a California based company is testing on 93 when it's hard to get 93 here.

[Stock4Evr]

Thanks to everyone who responded. After reading all you comments and comments from another BMW blog site I will go with 91, no more/no less. So much to learn, so little time.

[bodega_bladerunner]

Originally Posted by NavSpook42

2012, 135i - Normal, mostly highway, driving. I fill up with Shell 93 Octane. I think I can go with 89 Octane. What are your opinions?

why would you want to? just stick to 93

[ShocknAwe]

Use the highest you can find. 91 or 93

[gjm120]

Originally Posted by SkullV

I also use 91. We have the same stupid gas here as you do in California. You can mix some E85 in for an octane bump but the car does fine on 91.

This probably isn't news to anyone, but, E85 really decreases mpg's.

Is the octane on E85 pumps shown as (R+M)/2 or RON?

[Stock4Evr]

Thanks for all the comments. Will go with 91 on the 325i and 93 on the 135i.

[davis449]

Originally Posted by NavSpook42

Thanks for all the comments. Will go with 91 on the 325i and 93 on the 135i.

I don't know of any stations east of about Junction, TX that have 91 Octane. The standard in this section of the state is 93 Octane for premium unleaded. It's this simple. If the label on the inside of the gas tank lid, or the one on the gauge cluster, says "Premium Unleaded Fuel Only", then that's what you put in it.

[ShocknAwe]

Originally Posted by gjm120

This probably isn't news to anyone, but, E85 really decreases mpg's.

Is the octane on E85 pumps shown as (R+M)/2 or RON?

If it's actually E85 it will be somewhere between 100-105 (R+M)/2. Here in the states anyway.

[PA135i]

Gas around me is either 92 or 93 Octane for premium unleaded. And they are the same price. Go figure.