Gasoline Octane Rating - What do you use?

[JimD]

I have a 2009 128i convertible. My wife has a 2013 128i convertible. Hers is slower due to the automatic but I just noticed BMW has different octane ratings in the owners manual for these two years. In my manual (2009) it recommends 91 octane but says a 128i should get 87 minimum and a 135i 89 minimum. In her 2013 manual, it recommends 91 octane but says 89 minimum without commenting 128i versus 135i.

I doubt anything really changed and I use 89 octane now, I used 93 for the first 10,000 miles. If I am going to do an autocross I fill up with 93 octane. She uses at least 89.

What octane do you use? Do you think the minimum for a 128i really increased from 2009 to 2013 or they just simplify the manual?

I will also state that I think there is no quality difference by octane - 87 octane is as "good" as 93 octane. The engine will not knock (detonate) as easily on 93 as opposed to 87 but that is the only difference. You might get more power at 91 than at 87 but that depends some on ambient temperature and load (more load + higher temperature = more tendency to detonate and more benefit of higher octane). I don't think I benefit from 93 octane in my 128i but a tuned 135i may make more power.

Opinions?

Jim

[themellly]

Honestly, what the price difference really if you add it all up to the total ammount of gas you put in.

Let's just pretend the prices are $3.80, $3.90, and $4 for 91.. and you want to put 6 gallons.

87- $22.8
89-$23.4
91-$24.

I personally only pump gas at a 76 or Shell since I think it's cleaner gas.. Even if BMW said you don't need 91 octane I'd still use it. It's like a 2 dollar difference and you can notice the difference in performance in any car really with the higher octane. So i suggest just pay up the extra bucks.

[Dackelone]

I religiously use SuperPlus 98 MON octane (comparable to 93 RON octane in the states). Over here BMW says you can use Super which is rated at 95 MON.

I do feel that when I can't find SuperPlus(when traveling) and I use Super, the throttle response isn't as crisp as with SuperPlus fuel and the engine sounds "different". The engine just feels better with the higher octane fuel.

[JimD]

I looked up the difference in my area and it is more like 0.15c each step (3.1, 3.27, 3.41 for 87, 89, and 93 octane) but your point is still valid. The price difference is small. We do not have much 91 octane around here. I didn't notice any difference dropping back from 93 to 89 but it might be there. I don't think going above 91 provides a benefit, however, since the engine is not apparently tuned to use more spark advance than it gets from 91.

Jim

[BenDiem]

OP,

I agree w/your assessment. Most automobiles manufactured today and of recent vintage, can adapt to lower octane ratings due to the complex electronics that can optimize the fuel/air ratio to allow the car to operate efficiently with lower octane; However, having said that, I'm still of the opinion that some higher compression engines, i.e., Vipers, Corvette Z06 & ZR1, Ferraris, Porsches, Lambos, et al, to include all turbo charged cars, require 93 octane b/c the manufaturer designed the vehicle to operate at peak performance, which is generally at 93 octane. Lets face it, these buyers purchase these type of vehicles for performance, eh? Moreover, vehicles that require 93, the manufacturer has noted the requirement either in the Owner's Manual, on the gauge cluster, and/or near the gas tank fill area.

The 128i should/will do absolutley fine with 89 octane. I would not go 87, b/c the 128i has a relatively high compression ratio. 87 will ping/detonate the 128i, especially in humid/hot weather, due to its high compression ratio.

I typically run 89 in my 128i, until the summer months, when I switch to 93, from May 1 through Sept 30. My other vehicles all get 93 or 91 octane, exclusively.

My 2 cents...

Best/cheers,

B

[ejm3]

I use 93 octane in my 135i. Not sure how it would run on anything less as I've never tried.

[1addyfan]

I always use the highest my gas station offers... which is 91 Premium.

I've never even seen 93, tbh, and don't care to.

[rking117]

I am 93 Octane everytime. I tried 87 once (dealer filled me up) and got so horrible gas mileage I will never do that again. it was the difference of something like 4 to 6 miles per gal. It still doesn't offset the cost but it makes it more reasonable to me. It also keeps me clean inside. I have seen the difference between the carbon build up on a car that has been running 87 vs 93 and it is no wonder that the 87 gas cars run rough. so 93 it is for me.

[meg180]

I always try to put shell V-power into the tank (93) if I can't find a shell then I go for the Sunoco Ultra gas (93) I try to get gas where they have the lowest ethanol levels.

[vertebra]

in my area (Atlanta) most stations have 87, 89 & 93 octane available. I have no choice but to get the 93 which I probably would do anyway. BMW has a list of preferred stations, I believe it is based on the detergent content.


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[1addyfan]

Pfft, You East Coasters and your 93 octane... :P

[doublevanosrc]

Nutin but 93

[Nixolas]

Gas is cheap and good quality here in the middle east. I use 98 Octane. Around $21 to fill up the tank.

[RoundelM3]

Originally Posted by doublevanosrc

Nutin but 93

Amen, bro!

[bmw1racer]

Originally Posted by themellly

I personally only pump gas at a 76 or Shell since I think it's cleaner gas.

I think that's a myth...

I've been hearing stories of this brand A gas being cleaner than that brand B gas for ages... Is there any proof of this?

[shodanusmc]

Use 93 in our 09 135 Vert in the Chicago area. Higher prices here. 87, 89 and 93 run around $4.25, $4.45 and 4.65 and seem to change daily. Goes up fast, comes down slow.

[Colt]

93. Going to try 100 soon

[uberschnell]

I use 89 in my 08 x5 and it works fine. I also add techron fuel system cleaner every 3K miles. I feel very little diff between 89 and 91 in that car.

I don't go less then 91 (ca sucks) in my 135i. Higher octane burns slower and the motor runs cooler in addition to having more power. I also feel a big difference.

On the track running a 100/91 mix v. 91 alone got rid of my limp modes on my 335 when it was tuned.

[tracer bullet]

93 exclusively. Slight pain in the butt since only BP has it around the Mpls / St-P area. BMW says that's what should go in it and (while I am an engineer and like to challenge things) I figure their engineers know more about this subject than I do.

[EINSER M]

camel piss ACN 91 here
but now i mix it with some E85 secret sauce

[Southjersey128]

They did a test between economy fuels and high octane on one of those British car shows. It showed a 5 horsepower difference between the cheapest they could find and Shell's premium. We pay a lot more than 15 cents a gallon for other mods, why not splurge. I'm v power only.

[bimmerfile]

I only put Shell V-Power 91 octane (contains no ethanol) in the 2008 128i Cabrio (and the X1) .
BTW, the price diff here (Canada) between regular Shell 87 octane and Shell V-Power 91 works out to $.62 per U.S. gallon (when I do the liters to U.S. gallon conversion).
So you guys stateside are getting a real deal on the octane upgrade.