Our local municiple airport only has 100LL. I use it in my shifter kart if I can't get MS98. It's 5 bucks a gallon. If I have left over gas from a weakend of racing I just burn it in my weed eater. Yea it loves 22:1 two stroke mix and race gas.

93 in the R56 is not a big deal when you are used to putting 140 bucks of diesel in work truck. For the week!!!!!!!!

 

I've read most of the threads talking about octane on this forum, this is probably by far the most technical and best.

I actually purchased the Mini (base) to be my 'economy' car, mainly because my girlfriend liked it but also because it is an absolutely proven platform for stock class auto-x (we'll see if that changes in the coming years. So, the question of fuel economy, what type of octane, etc. is a very valid one for me.

I'll start by saying I've got an 06 Evo IX MR with about 23,000 miles on it that I would never even dream of putting anything under 93 in it. Besides the fact that premium is unquestionably required from the factory, the car has specifically been tuned for 93. Even then for evos, depending on the tune, you can still pick up knock if the conditions are right (bad).

As far as Minis (again, base) go though, kind of funny what some people are saying. Depending on the condition of your car, you won't suddenly start knocking with a lower octane on a hot day outside - I really think it applies to lapping/pushing the car, and even the the motor seems to make some kind of an effort to retard timing on its own - safe to say the evo will not do that lol. That said, when I go auto-x I will absolutely be using 93 in the car.

I completely get what people with forced induction Minis are saying, but I really think base coopers are a different story. Cruising on the highway in a base cooper shouldn't result in any sort of detonation, any harm really. Autox/Track, definitely a different story, so there is some to do with personal driving.

I'm sure most people aren't even tracking the car, but it's kind of funny how concerned they are about what's going in the car as far as fuel goes.. are these the same people who put crap like McDonalds/fast food and soda in their own bodies?

 

I have a naturally aspirated cooper hardtop. For my second fill up, I made an error and filled up with regular unleaded. The fuel economy indicated by the display in the tach ran in the mid 30's. the cars acceleration and throttle response were affected negatively as well. I was ready to take the car in for service under warranty. I then realized it was my fault because I put regular unleaded in it. Next fill up, I put 12.5 gallons of premium. The mileage returned to the high 38's and the feel if the car returned to normal. I now will make sure I don't make that mistake again!

 

In hotter weather with the air conditioner running any thing less than 93 octane will start the engine knock'in. Been there/done that.

 

I am lucky here in that our local fuel distributer has public pumps on his yard open 24x7, card only. One island is no ethanol, so I run no ethanol premium. Early in her life, my clubbie was in WA state and no ethanol was not avail. I also avg. about 30 to 40 more miles per tank with non ethanol fuel. I plan to run Lucy when she is built and delivered on only premium no ethanol.

 

really?? that's pretty surprising

 

This has prolly be said... but I know when I first got my Mazdaspeed 3 I used 87 but switched to 92/93 and got a lot better gas mileage.

 

Truly.....and I live in the Northeast where my summers are typically in the 80's.

 

Probably a stupid question, but why does the USA have such low Octane ratings for fuel?

(I'm from the UK originally, and seeing 87 was somewhat of a surprise...)

 

I just read this entire thread, then googled "minimum octane requirements mini cooper" and found this:
http://blog.bavauto.com/8301/bmw-and...my-vs-quality/
After reading all this, Im still not sure if I should be running 87 or 91 in my justa. My goal is to get the most miles per dollar spent. If 91 costs 15-20 cents more per gallon (here in NJ), would my marginally improved mileage (over using 87) justify the marginally increased cost?

Anyone have any experience with that?

EDIT: I know I can calculate this myself by running a few tankfuls with 87 and a few with 91 and adding up the miles driven and fuel cost, but was wondering if anyone's already done this with the NA engine.

 

The number is calculated differently: the number you see is the Anti-Knock Index, which is the average of measured (actual) vs research (theoretical) octane. (RON+MON)/2 = AKI or the hunger on the pump. In Europe and the UK, RON is the usual reference point.

Sent from my iPad using NAMotoring

 

I would use 91 because in the end that will end up being cheaper by keeping your engine cleaner will prevent expensive problems down the road more than a few bucks a tank...

 

excerpted from the link I posted earlier:

Here are some of the common misconceptions:
* Higher octane equals higher quality fuel (false)
* Higher octane equals more engine power (false)
* Higher octane equals better fuel economy (false)
* Higher octane burns cleaner in my engine (false)
* Higher octane is better for the catalytic converters (false)
* My BMW or MINI must use higher octane fuel because it is built to do so and will be damaged if this is not followed (false)

I'm not worried about the possibility it will burn "less clean" with 87, just whether it's the optimum tradeoff between cost and mileage.

 

The owners manual states 91 octane is recommended. My cars acceleration and miles per gallon is better with 91 octane.

 

I use only 93 octane and my car clearly gets better gas mileage as well as acceleration. My car does knock when I tried 87 octane. None of these facts arefalse. If all the things listed are false then why offer higher octane levels? Just raise the cost of 87 octane.....if profit is the rationale.

 

My guess is that higher octane fuels are offered for sale for engines with higher octane requirments.

 

So what is the long term effects of running 87 for those that have run it? It has been 3 years since this thread started and I was just wondering if those people had any engine problems or other mechanical issues.


I already know most of them bounced because they can't hold onto a car more thena year or two but, I have to ask.

 

.....Which is not a BMW or Mini according to what you wrote. This, even though the Service Advisor says you must and the owners manual also says so?

 

I use premium Shell gas, I believe it is the only gas around in my area (NY) that does not contain ethanol. More pricey, but I think it is the best gas for our cars. Anybody concur?

 

I am a bit confused: what are you rebutting? If the subject is non-BMW/MINI engines then what does a service advisor have to do with the price of tea in China?

Just trying to follow. Thanks!

 

Sorry if I was unclear. My interest is in the cost-effectiveness of 87 octane for a normally aspirated (non-S) engine. Since the minimum octane requirement is 87 but mileage might be better with 91, I was trying to figure if the marginal improvement in mileage was enough to justify the marginal increase in price per mile of using 91 vs. 87. Since Mini has officially stated that the minimum is 87, I'm reasonably certain there would be NO harm to the engine in using 87 octane, so I'm not asking that question.

 

I have never tried 87 but with 89 and 91 Chevron (California formula) I have these results on 175/65-15 Continental summer tires fitted year round:

89 2633.4 miles 70.45 gals 37.38 mpg
91 6971.5 miles 186.18 gals 37.44 mpg

 

It looks like the net benefit between 89 and 91 is practically nil. I'd still be curious what the difference is between 87 and 89. Here in NJ those 2 grades can be as much as 20 cents apart on any given day.

 

I agree! I've had a GTi 1.8t for 12 years and wouldnt/couldnt put anything less than 89 octane in it. Even then, I'd add some Berryman's Chemtool to the tank every few fillups out of guilt. I knew that 89 was a minimum requirement for the engine to perform properly and have resented it since fuel prices have continued to climb (especially post-Katrina).
Since my new Justa will be a daily driver, my goal is to keep operating costs in check while enjoying my driving experience as much as possible. That's why I decided on a Justa rather than an MCs.

 

Bratling,

Komet155 stated the following as being false :

*My BMW or MINI must use higher octane fuel because it is built to do so and will be damaged if this is not followed (false).

I then asked:

*If all the things listed are false then why offer higher octane levels?

Komet155 responded:

*My guess is that higher octane fuels are offered for sale for engines with higher octane requirments.

I then ask:

*......Which is not a BMW or Mini according to what you wrote. This, even though the Service Advisor says you must and the owners manual also says so?

While Komet155 states that BMW and MINI is not built to take high octane gas ("false" Komet155 says), Komet155 then states that high octane gas is for cars with higher octane requirements. Isn't that contradictory? These are cars that require higher octane requirements according to BMW/MINI. I own 2 Mini's currently (a 2008 base and a 2012 base) and each time at delivery my service advisor advised about fuel requirements and that 91 octane is the recommended fuel. My owners manual's says that the recommended fuel is AKI 91. It also says though that the minimum requirement is AKI 89. (JCW is AKI 93). I don't see where MINI has an "official" announcement of 87 being acceptable. I go according to the written word in my owners manual for performance, longevity and warranty sake.

Thanks for asking as I, too, tried to piece this information together as it pertains to fact, considering opinion, and reading of a report of an "official" announcement. I'll stick with 91 to 93 octane as the owners manual recommends. Thanks to everyone for sparking this conversation and contributing. Theres alot to consider here.