Octane question from a newbie!

[KWMN33]

Just purchased a 2013 X5 35i Premium yesterday. My first ever Bimmer!

Quick question - and certainly there don't seem to be a shortage of threads about this, but wanted to ask specifically as it pertains to the X5:

Our local gas stations don't seem to have 91 Octane (the BMW recommended fuel) as often as they have a combo of 89 and 92/93. Is the wisest course of action to:

A) Always fill with 92/93 octane if there is no 91?
B) Always bill with 89 octane (it's just fine for this particular engine)
C) alternate between 89 and 93 (in theory, it evens out to 91!)
D) seek out gas stations that actually have 91 and just stick to using them

Any advice would be great!

[m5 guy]

92/93. It will be better for your engine. 91 is the minimum required.

[KWMN33]

Originally Posted by m3 guy

92/93. It will be better for your engine. 91 is the minimum required.

Oh... my manual said 89 is the minimum required. Is that something that's generally changed over the past 2-3 years?

[P1]

Option A... I think minimum is 91.

[KayTees]

Mine says Minimum 89 but in Canada, I tried a little experiment, I put in a maybe a bar Chevron 94, drove it around and it felt normal, put Shells 91 and I drove it around for a bit, it felt sluggish and completely different. That's just me tho, the proper way is to probably dyno it.

[goodmaj]

I've found that the biggest difference is if you can get gas without ethanol. If you can, there's your new best friend. Otherwise, stick with 93.

[serge1]

More octane -> gas is less explosive -> allows more compression -> more "bang" once finally ignited.
Modern engine computers are able to adapt to octane levels in fuel. The engine will be fine, just less power, that's all.

[Klimo]

Originally Posted by KayTees

Mine says Minimum 89 but in Canada, I tried a little experiment, I put in a maybe a bar Chevron 94, drove it around and it felt normal, put Shells 91 and I drove it around for a bit, it felt sluggish and completely different. That's just me tho, the proper way is to probably dyno it.

Octane rating has absolutely no impact on power output. Only if you put in octane that is not recommended for your engine. If 91 is recommended, then putting in 94 makes no difference.

[KWMN33]

So if 91 is recommended, then putting in 94 is totally fine (but putting in 89 isn't ideal?) Just want to clarify. Thank you all for the helpful answers!

[theaudir8fan]

I would say always go for 92/93 on premium cars, don't cheap out on gas. If you want to track down, try getting fuel that doesn't contain ethanol

Originally Posted by KayTees

Mine says Minimum 89 but in Canada, I tried a little experiment, I put in a maybe a bar Chevron 94, drove it around and it felt normal, put Shells 91 and I drove it around for a bit, it felt sluggish and completely different. That's just me tho, the proper way is to probably dyno it.

I completely disagree with you, the Chevron 94 simply doesn't feel up to par as Shell's 91. From my personal observation, the Chevron 94 in BC get an average of more than 35kms less of range from a tank and it doesn't perform as well on track. I know someone with a M4 who get around 5mph slower trap speed in the 1/4 at castrol on 94 compare to Shell 91. He also works for a machining company that does servicing for the refineries and says that Chevron's standards is simply not up to par compare with the others

[Flying Ace]

I put diesel in mine. But not recommended for you

[KayTees]

Originally Posted by Klimo

Octane rating has absolutely no impact on power output. Only if you put in octane that is not recommended for your engine. If 91 is recommended, then putting in 94 makes no difference.

Never said there was a gain in power, I just said that when I have 94 then go back to Shells 91, the car just feels more sluggish.

[Poppyboy]

Just filled up with Mobil 93 last night at 2.99/gal. What a deal! I rarely see 91 available in the Chicago area.

[UglyBuzzard]

In CA we get 91 - what would be affect by adding octane boost?

[SlowBucksE70]

Originally Posted by Poppyboy

Just filled up with Mobil 93 last night at 2.99/gal. What a deal! I rarely see 91 available in the Chicago area.

Wow
BP 93 octane in jersey is $2.23cash and credit.. BP rewards help as well

[Poppyboy]

I couldn't fathom ever using BP after what they did to the gulf.

[heatmizr]

PoppyBoy wrote:
"I couldn't fathom ever using BP after what they did to the gulf. "

Well then you better avoid Exxon as well, for decimating 1000 miles of pristine Alaskan shoreline...
http://www.theatlantic.com/photo/201...-today/100703/
Actually make that Exxon-Mobil - they merged in 1998.

Your options may reduce further as you do more research...
Its guys like us, though, with X5s that drive the need for oil to travel around the world

I'm with the poster above who suggested looking for NO ETHANOL above all else. Ethanol is detrimental to lots of stuff! I want to avoid it at all costs ESPECIALLY for motorcycles and older model vehicles. But it's in the gas freaking everywhere...
Also, at the ONLY station near me that has/had ethanol-free, the price jumped up to $1.50-2.00 higher than any other octane choice. I complained to the owner and he said the parent company he franchised from controlled it, nothing he could do.

Second, I highly recommend checking out Top Tier Gas:http://www.toptiergas.com/
It's a shame not more people have heard of this. Lots of smaller brands listed here; though PLS NOTE you MAY need to purchase the Premium fuel offered to get the Top Tier offering.
BMW is the first manufacturer listed here supporting this fuel rating.
Unfortunately Top Tier does not necessarily mean no ethanol...

This article speaks of Shell specifically (V-Power!), also mentions BMW at the end - and that apparently Shell gave away 100 BMWs earlier this year?? How did I miss that?!
http://thechronicleherald.ca/wheelsn...e-a-difference

[goodmaj]

Interesting that Costco is on the top tier list but not Sam's.

[JGard]

Originally Posted by KWMN33

So if 91 is recommended, then putting in 94 is totally fine (but putting in 89 isn't ideal?) Just want to clarify. Thank you all for the helpful answers!

Due to the timing and compression level of an engine, the octane ratings make a difference in whether or not you can damage your engine more than anything.

So if it calls for a minimum of something, it's because that level of gasoline won't pre-ignite (meaning it won't explode before the spark plug tells it to) under that engine's ideal running conditions. Prolonged detonation/knock will absolutely destroy an engine. Ironically, diesels actually are made to run this way (no spark plugs) and it's part of why diesel engines can last so long compared to gas counterparts.

As someone mentioned, most cars today can sense when that's happening (they have something called a knock sensor) and will retard the timing of the engine to eliminate that problem. The result of retarded timing is less power and often less efficiency.

So while in the very short term some bad gas could "hurt" your engine, the car's ECU will notice and adjust accordingly.

[Flying Ace]

Originally Posted by Poppyboy

I couldn't fathom ever using BP after what they did to the gulf.

you're a good candidate for a bicycle as a primary mode of transport.

every oil company has had issues in the past, evironmental and political.

[Poppyboy]

Yeah, but few so blatantly criminal as BP.

[P1]

Originally Posted by Poppyboy

Just filled up with Mobil 93 last night at 2.99/gal. What a deal! I rarely see 91 available in the Chicago area.

I filled up over Thanksgiving for $1.89 a gallon. And that was for 93.