MA said premium during break in period then follow gas cap rating.

In my area we can buy 87, 89, and 93. There is no 91. My gas cap says 89 or higher.

Anyways, did a search and found quite a few things, but nothing on 2013 and everything said 91. I've been using 93, have no issues continuing. Just curious why the cap says 89. I understand the cars are built in Europe and all, and their ratings/ethanol are different, but think they would change the gas caps for US-bound cars.

Thoughts?

 

have you checked your owner's manual? in p.111 of mine (2011, Justa Clubman),
Super Premium gasoline/AKI 91. This gasoline is highly recommended.
The minimum AKI Rating is:
> Cooper S, John Cooper Works: 89
> Cooper: 87

 

So according to your manual (and probably mine) the gas cap is correct. 89 rating or up. Meaning here in my area that I can use mid-grade and up... if I follow that anyways.

 

You're lucky you have access to 93. Many people, myself included, would give a lot to have regular access to 93 octane. Do it for us, man; do it for us. Go 93.

 

Haha. Okay. Yeah I can't get 91 here at all. It's straight from 89 to 93 (like shell 93 with v-power stuff). Any station I stop at has that.

Ill do it for you!

I've been using it so far since I got the car (2500 miles) but wanted to just ask since the cap does say 89 on it. I believe the number have to do with the detonation and I read somewhere using even higher grade than recommended could be bad. Wasnt sure validity of that statement though.

 

Higher octane will give you more power, as the engine control unit will advance the spark automatically to take advantage of it.

Different states have different laws regarding fuel formulation, you can't find 91 octane because you live in a 93 octane state is all.

Dave

 

My understanding is using octane lower than what the engine wants will cause the engine to adjust its timing to reduce power, but using higher than needed octane has no benefit at all. So if your engine is designed for 89, using 91 or 93 just wastes money.

If you want to splurge on premium fuel during break in, go for it. If you track your gas mileage for each fill up, you can compare the fuels and see what makes your car happiest.

 

No, the Engine Control Unit works both ways on our MINIs. Higher octane on a modern ECU controlled car will result in a little more horsepower. It is on older cars with no knock sensors or ECU controlled timing, where the octane has no effect on the power output.

Dave

 

No, the engine was designed for 91+. It is capable of running a lower octane with no damage.

 

Some other considerations...

If the car is going to sit a lot, you may want to use a higher octane than required due the fuel will degrade in the tank. Consider this if the car is going to sit for weeks at a time with the same fuel in the tank.

If the car is going to be heavily loaded (towing or racing) or driven in very high temperature regions, you may want to go with the higher or even the highest available octane.

My understanding of the octane rating: it is a rating were if the rating goes up, the higher the pressure and temperature the fuel will detonate at (without the aid of a spark). Higher octane fuel will also burn more slowly at a given temp and pressure.

So, in an engine, if you have heat soaked it, and are still demanding high power (compressing the air and passing it through a heat soaked intercooler) the chances of getting to the temperature and pressure were the fuel will detonate all at once (rather than a flame front moving in an orderly fashion across the combustion chamber) are higher with the 'rated' octane (89 here) than with a 91 or 93 or the vaunted Ultra 94 one can sometimes find...

Buying high octane fuel is insurance in high demand situations.

There should not be a power difference from the rated octane for the engine to higher octanes (unless you have heat soaked the engine etc per above) as they all have the same caloric value - BTUs per lb of fuel should be the same from 87-94 Octane.

What happens is that if the octane is too low, or knocking is detected, the computer retards the timing and richens the mixture to simulate a higher octane - ruining your fuel economy, but saving the engine!
Under normal circumstances, the computer will advance the timing (I've seen 40+ deg) to extract the most out of the fuel - let it all burn then let the created pressure push on the piston for as long as useful/possible. If it detects knock, it will retard the timing first to cool the chambers (the hot burnt gasses spend less time in the chamber before being pumped out the exhaust), then spew in extra fuel to further cool the chamber (dirtier combustion, and more 'cold' fuel in the chamber) all to eliminate the knock.

I have run both 91 (usually) and 93 octanes and seen no change in the behavior of the engine wrt advance, "butt dyno" or fuel economy. I don't often see 89, and won't run 87!
E
2012 MCS

 

This has been beat to death here, like the horse has already been buried. Price wise you are talking pennies over a whole tank of gas. Pre-detonation(knock) will destroy an engine even with the ECU controlling it. Knock will eventually crack a piston, melt a ring or worse crack the block. Please save us the "I fried my engine, F MINI" thread and use 91 and above.

 

Hello, I brought home my 2012 Mini S today. I stopped to fill-er-up on the way home, needing about 3/4 of a tank. I was told to use regular gas, which I did, at Costco. Do I need to have the gas tank emptied and then refill with high octane gas before I drive it? I live in Central Florida where the temps are rather chilly now but that will change in a day or two and summer is closer to us than to most people. The ride home in my new car was a hoot! I'm going to love this little car.

 

Not sure why you think that contradicts what I said. I said, "using higher than needed octane has no benefit at all," and "if your engine is designed for 89, using 91 or 93 just wastes money," both of which I still believe are correct.

What I didn't know until checking the manual just now (I don't actually have my MINI yet) is that MINI recommends use of US octane 91 fuel (except for JCW, for which they recommend 93), but MINI allows use of anything 89 or higher.

So this suggests there will in fact be some benefit to using 91 instead of 89, but you shouldn't expect any additional benefit from going higher in a non-JCW vehicle.

Point is, higher octane doesn't mean more power, once the octane is high enough.

References for those who care:

• http://www.consumer.ftc.gov/articles...ctane-gasoline
• http://www.economist.com/blogs/babba...octane-ratings

 

And then you went on to say, "If you want to splurge on premium fuel during break in, go for it." The clear implication in context is that you thought the OP would be wasting money by "splurging" on premium fuel during the break in period. Probably driven by the fact that you did not know MINI recommends 91 or higher as you learned once you did some research.

I suppose it is possible you consider following the manufacturer's recommendation to qualify as "splurging".

 

PLEASE PEOPLE

do a little research on what the term "OCTANE" means

AND recognize that the way an OCTANE number is calculated differs between the US and most of the rest of the world!

It is sometimes so sad to have even the most basic understanding of chemistry

Point is, higher octane doesn't mean more power, once the octane is high enough.

well said and if you don't agree - U R WRONG

 

It's a little more complex than that.

Octane rating is a measure of a fuel to resist knock or pre-ignition due to compression. Regardless of the method used to calculate the octane rating, a low number means less resistance to pre-ignition and a high number more resistance to pre-ignition.

Igniting the fuel closest to top dead center, at the point of highest compression, (ignition advanced) allows the flame front to travel the least distance, burning all the fuel quickly, raising combustion pressure and increasing the downward force on the piston and raising the horsepower produced.

Higher octane fuel lets the engine control unit advance the point of ignition closer to that of most efficiency, Top Dead Center, resulting in higher combustion chamber pressures and more horsepower.

The horsepower increase, with high octane fuel, is all due to our smart Engine Control Units.

It's just physics, "and if you don't agree - U R WRONG"

Dave

 

And this why this conversation has been beat to death. This comes up every time. 89 might be fine but, increasing your chance of knock and decreasing the life of your engine. In a Cooper this is not as big of a deal though they still have high compression. In a JCW and MCS this dors matter because of the forced induction and the increase in compression. All in all not my car do what you want.

 

No need to drain the tank. Just drive it to use some gas, then add in the octane you want. Fuels having different octane ratings mix as you might expect, e.g. a half tank of 89 plus a half tank of 91 is like a full tank of 90. Assuming you slosh it around enough to mix it well. Gives you an excuse to drive twisty roads...

 

My gas station ONLY has 87 or 93... 93 it is!

 

Seabeast, thank you for your answer. I feel better and will get more gas, at higher octane, as needed. My new Cooper S is also Spiced Orange, with Black roof (dual sun roof), automatic, with lots of toys I'm just learning about. It made it's first trip to WDW today and the drive was a blast. Thanks again, I had just about given up hope of a response.

 

1.) In an internal combustion engine, the spark is initiated well before the piston is at top dead center. If the spark timing were at TDC, the engine would not run. Usually spark is started at 20 degrees before TDC, or so, and based on the load, O2 sensors, other sensors, tuning maps, the ECU will adjust spark timing, fueling, cam advance or retard(VANOS), wastegate or bypass control...


2.) the ECU can only adjust so much. If it needs to be outside it's range of operation, or parameters are out of normal expected range, it effectively says WTF? and you get a check engine light.


Ok, so will the engine run on 87? Of course it will, the engine control system is robust enough, (engineering term) that it should be able to adjust for that. Will it make the same power? No. If using 87 produces knock under load, the ECU will try to eliminate it by reducing ignition timing advance, adding more fuel, lowering boost, until it can't.

All of those things reduce power.


It's even more of a problem if you have tuned the ECU. Tuners assume you will use a specific grade of fuel and NOTHING LESS. And no, I'm not talking about driving gently, at light loads, but about really stressing the engine by being a hoon...lol


There's one other thing to consider about premium fuels. It's the additive package that is injected into the fuel as the truck is being loaded at the oil supply terminal. The additive package for premium fuel was much different that the package for regular and plus grades.

(or even for the premium gas we sold to other oil companies. Yes, it's entirely possible that the gas sold at your Exxon/ Citgo/Shell/... You name it station, came form some other oil companies storage and loading facilities. Gas is pretty much a fungible commodity)


Anyway, back when I was the loading terminal manager for a major oil company here in Baltimore, the additive package we used for OUR premium gas was about 10 times more expensive than what we used in the regular and plus grades. (or other premium we loaded for other oil companies) All the additive packages met federal requirements, but our premium package was way better. (Hint, Leon Hess used to own the NY JETS)



Sorry I digressed... The car will probably run on just about anything (gas wise), but you will lose power if you don't use the maximum octane the car is tuned for.

If you don't have plus gas, you can make your own. It's a simple blend of premium and reg. about 65R/35P (where do you think plus in a truck comes from? There are only reg and premium base stocks... It's blended at loading, or at the pump)

 

Reading the manual (OK a weird 'out there' act for most posters) for both my Australian spec Justas it says (paraphrased) the car will run on 91, is better on 95 but for the best performance and economy quoted in the handbook use 98. Guess what I run - yep 98 JUST LIKE THE BOOK SAYS.