I've been using regular gas in my '06 MC 5-spd since it was new. Last year I drove out to San Antonio from Cleveland,Oh in Jan using reg and averaged 34.6mpg calculating every tank, not using an onboard computer. This year I decided with the drop in gas prices I'd experiment and use the high priced stuff. I went out the same routes and then went on out to LA for a couple weeks and back to San Antonio for another week before returning to OH. This year I averaged 35.1 mpg using 92 oct. at 20 to 30 cents more per gallon. Any performance difference was imperceptible to me without using a stopwatch. Tell me again why I should use premium.

 

as it depends on lots of things about what you drive and how you drive. With a boosted engine, I've logged timing pull,even with premium. This lowers mileage and power. But you've got a base cooper, and I don't have a lot of data about how sensitive it is to lower octane and timing pull.

Matt

 

You've got to be kidding. Consider a XB.

 

Keep in mind that highway droning (even at high speed) is the least demanding on your engine, so you probably wouldn't see the benefits of higher-octane gas on those trips.

I routinely make 3-4k mile cross-country trips, and I purposely alternate tanks between the highest-octane I can get and the lowest-octane I can get, just to see what it does to the fuel economy. I've used as low as 86 AKI and as high as 94 AKI on those trips and have *never* seen a correlation between fuel octane and highway fuel economy. (supercharged MINI with no engine modifications)

But for my normal around-town driving, I've tried the lower-octane gas a few times and have always taken a small hit on fuel economy.

 

i just purchased an 09 S JCW drop top and filled it up this morning for the first time since the dealer had a full tank. it took $29 worth of ultimate 93 gas from BP (go green!). I look forward to seeing what kind of better mileage I get with this, as I believe I am through breaking the car in. (higher speeds, highway driving to and from work).

 

I have read a lot on the subject and what I found out is that if the manufacture recomends premium then you can use a lower grade. If the manufacture says you must use premium then that is what you have to use or take a chance of voiding the warranty.

 

A good rule of thumb is that if you have forced induction (turbo or supercharger) or high compression (10:1 or more) then you should use Premium or risk detonation (knocking). If its a normal engine without the above, then regular is fine, just stick with a brand you trust.

 

I love it when people acutally "invesitgate" things, and do some reading and research! I have done the same... this is what I came up with-- similar to what you are saying, but a different take on it.

Octane levels are higher in Europe and the UK. The MC and MCS were not necessarily designed to "require" premium gas in those countries, simply because in many cases, their regular grade gasoline is over 90 octane.

Our octane levels are much lower... and that is why premium gas is "recommended".

I put mid grade 89 octane in my car once just to see what it would be like and it was a bad experience. Engine ping, hesitation, lack of throttle response... this was in a MC and not an MCS-- but, everyone needs to remember... it is essentially THE SAME ENGINE in both cars.

Additionally... I have a feeling that the altitude at which you live could have an effect on vehicle performance. Anyone know anything about high/low altitude and octane levels?

 

The R50 engine has 10.5:1 compression, so I personally would recommend mid or high grade just based on the compression.

The R53 has 8.5:1 compression, but the blower puts out 10-11 Psi of boost (stock)...definitely high grade time...

 

The "better gas in Europe" thing comes up in every gasoline thread, and it's simply not true. European countries just label their gasoline differently than we do in the U.S. (Europe uses RON rating, while the U.S. uses AKI rating).

The **exact same gasoline** that would be labeled "98 octane" in Europe would be labeled as approximately "93 octane" in the U.S.

In short, the U.S. doesn't get lower-octane gasoline - we're just more conservative in how we rate it.

As for the altitude/octane issue - in general, higher altitude requires lower octane for any particular car. That's why "regular" in the Rockies is often 85 octane and "premium" is often as low as 91. The rationale is that since the "thinner" air contains less oxygen, you're not going to be able to pack as much oxygen into the combustion chamber. Combustion chamber pressure will be lower as a result, so you don't need as high of an octane rating to prevent pinging/detonation.

This doesn't exactly hold true with ECU-controlled engines, especially turbocharged engines, because the computer can raise the turbocharger boost to force the same amount of oxygen into the combustion chamber even with the thinner air. So a turbocharged car could take advantage of higher-octane gas, even at high altitudes.

 

I just purchased a 2006 Cooper S from the first owner when I asked him what gas he puts into the car he said 89. I can't wait to fill her up with 91.

 

I'm needing some advice. I'm not sure if it's a fuel problem or not, but my 2003 MCS is running really sloppy at 2-3k rpm. Very bad hesitation. It's only been happening during the last few months and I'm not sure how to fix it. Does anyone think it could be a fuel problem?

 

 

Has anyone had the computer not communicate with the NYS state inspection computer even though the state computer shows connection? Can the computer in the car be reset by unhooking the battery for a short period of time.

New to site, not certain where to post question?

Thanks,

wfrivet

 

i cant comment yet because im still running around on the free tank of gas the dealership supplied me with (that was a week and 300 miles ago)

 

my '04 R50 CVT has over 100,000 miles on it, and is used three nights a week for food delivery. i only put in valero 87 octane, and exxon 87 octane, my engine still runs like new, and i'm still getting over 20 MPG in crazy stop-and-start suburban traffic. my mom switches back and forth between 87 octane and 93 in her lexus to see if there's a difference in MPG, and though you notice it, it's not enough to justify the difference in price.

i have some friends who are car nuts who think the whole octane ratings thing is nonsense, and i don't disbelieve them in a second. however, once i'm done freshing my mini up (that might be a 2 year project, so don't get excited too quickly), she'll be joining me upstate at school, where i will probably either feed her 91 octane, or mix jectron into the tank one month and ventil sauber the other month, back and forth. but from my experiences, in suburban driving about an hour outside of new york city, 87 octane in a bone-stock R50 is trouble-free.

 

Hey, I'm new too. Bought the Cooper a year ago but haven't used a MINI forum until now. BUT....yeah used regular to begin with, now up to midgrade which seems fine. Great mileage so don't worry. I fill mine up every 2 weeks whether it needs it or not.
So what comes after 50 thou? Anyone? Really, love driving the car though it took a while to get used to the idea of a car that small, but I love it.

FIREMINI

 

i just bought an '05 mc 2 weeks ago. didn't think about octane... couldn't get to the owner's manual in the glove box( broken lock, which was replaced by the dealer), and i filled it with good 'ol 87. with nothing to compare to i thought it ran ok. but then i talked to an owner of an '03 who used 87 octane and suffered carbon buildup and fixit $$. i then started using 93 and mine runs much smoother, more zip, and better gas mileage through the last 2 tanks(i drive it alot). i'd rather spend my money at the pump!

 

hello everyone! well i have put regular and midgrade in my mini and i can definately see the difference in what my car can perform

 

300 miles on one tank! If you're not on the highway a lot, you're not pressing the right pedal hard enough

 

and an 08 Clubman... The prince engines are much more frugal. We get over 500 miles on a tank with the Clubman pretty regularly! It's not an S though. I'm guessing the S can get over 400 miles on a tank pretty easy...

Matt

 

the key is what you need to do with your car, if you drive miss daisy around all week, put regular in the tank, if you go to carve your nearest canyon road, put in super.

octane number means fast burn gas or slow burn gas. that is all high octane burns real slow that is why it resists pre-detonation

if you use racing fuel to drive miss daisy you might burn exhaust valves or just get carbon build up in the fire chambers, because you are not burning the fuel hot enough

im working on a 03 mc s that is sputtering after it is super hot. the lady drives it around town like a taurus station wagon and uses super.

the motor has a mechanical comp ratio of like 8.9: 1 , before the charger kicks in. if u dont gun it, the charger wont engage, and at 8.9:1 that is probably the taurus comp ratio......... so she NEEDS to run regular unleaded

my 2 cents

 

03 mc s 96 k still kikin'. HARD

 

If your not willing to pay for the premium fuel for your baby that you paid a premium dollar for why buy one....I just bought a MCSC love it an only put premium in it. Runs awesome very happy to be part of the cooper family.

cheers

 

Better idea, ya'll. use E85 instead of the petti 91 oct premium. E85 has a WOOPIN' 103 OCTANE