I'm currently driving an Infiniti G37. My wife drives an LR2. Both recommend at least mid-grade. I always get it for my car. My wife refuses and buys only regular. Never noticed any underperformance on her car. They say regular gas takes a little bit off of the performance and the gas mileage.

So, I'm getting a new mini in a bout a month. Premium gas. Where I live, premium costs 30 cents more per gallon than regular, and 10 cents more than mid-grade.

What do you folks use in your minis? And is there any noticeable difference if you don't use premium?

 

El, is it an S? I have used premium exclusively for the 20 months Ive owned mine. Yea, costs a bit more but is $4.20 more per tank worth a little extra peace of mind? I think it is, you have to make your own call. Just remember, this engine is 11:1 static compression ratio and runs 11 to 13 pounds of boost on top. Given how "delicate" these things seem to be, I would recommend it. My Pathfinder recommended Premium but it was just a stock 4 litre so I ran it on Reg w/ no trouble, it was approved but Prem recomended. All depends on the engine.

 

You should definitely get at least the lowest recommended octane for you car. Saving a few bucks a fill up isn't worth it if you have to drop a few k on a new engine in a year.

 

Mid grade gas will work but cost you 2 or 3 hp. Not a bad trade off. Incidentally, I had a G37 three cars ago. Loved the way it drove but it was too small for me to sit in comfortably. Got tired of laying down in it.
The Mini is less refined but loads more fun to drive.

 

High compression engines require the resistance to combustion provided by high octane fuels. If you are getting an 'S' and somehow manage to not use the FI, you'll be fine on regular.

I've read that when cruising on the interstate, people are getting the same or similar fuel economy from regular, but in-town fuel economy is greatly diminished because the engine is having to adjust its settings to sub-optimal timings. In this case, I would say that the total cost in-town is probably the same or worse with regular as with premium.

Unfortunately, I haven't taken delivery of my MINI, so I can't say...and even then, I will not be running 87 to give you numbers.

Edit: Note that I have owned a turbo Volvo in the past, and premium was (naturally) specified for the engine.

 

It doesn't cost that much if you look at how much the difference is annually. Just figuring 12,000 miles a year at 30 mpg is 400 gallons. At the .30 difference your only talking $120. Thats the way I look at it, $10 a month is skipping 1 fast food stop. Well worth it considering the expense.
On a side note I recommend trying to find ethanol free premium, puregas.com list most of them. I noticed a 2-3mpg increase

 

He he. Good point. Thanks to all for your repsonsees. Yes, I am getting an 'S'. I guess my question is, will regular or mid-grade actually HURT my car, or will it simply detract slightly from performance. Does Mini have a stated policy on this?

 

In my area near Hoboken, premium is about the same 30 cent difference over regular. When you do the math, that's about $4 a fill-up more than regular. If you fill the tank up 3 times a month (which would account for about 1,170 miles of driving ((30MPG Avg and a 13 Gallon tank, which it's actually slightly larger and generally gets better mileage than 30mpg)) than you'll pay an extra $12 a month and $144 a year.

Isn't $144 dollars worth it to keep the car running better in the long run? Moreover, look at it this way...if you lose 2~3 mpg by using the lower grade fuel, than 27 mpg X 13 gallon tank is 351 miles a tank. Using the same idea as above (3 tanks a month), instead of getting 14,040 miles out of 36 tanks of gas on premium fuel, you'll get 12,636 on regular, which means you would need to buy an extra 4 tanks of gas to go the same distance.

Long story too long, you'll end up paying the same amount one way or another in the end, so the short term savings are non-existent in the long run. If you fill up more than 3 times a month, it'll be cheaper annually to use premium. The only way you really win by using cheaper gas is if you put far less than average mileage on the car.

 

There are lots of threads on this topic. Search will reveal them to you.

The bottom line is that MINI recommends high octane for forced induction cars. Gas stations in my area increase their prices in $0.15 increments between grades. Me, I'm not skimping on what I feed my baby. ~ $4 per fill-up increase is worth it. She gets only Shell, high-test (93 octane near me). To me it's the price of admission for driving this car and I'm willing to pay it.

Yeah, you can technically put in low or mid grade, but is the cost savings worth it? For the drop in MPG and compromised performance, my answer is NO.

 

OK, not intended as a snide question but - how long have you been driving and what's the oldest car you've owned?

Back b4 computer controlled ignition one regularly checked their ignition timing as part of a tune up - if your timing was off the performance suffered and the engine might knock among other things. Knock is the noise you here when the engine is experiencing 'pre-ignition', that is the fuel is cooking off at least partially b4 the spark is telling it to. In a worst case, knock damages the engine. In the late 60's and into the 70's you could still buy high compression V8's with big 4 barrel carbs that drank high test at 7 miles to the gallon!

Then came the gas crunch. If you could even FIND high test any more, the cost was way up and lets not forget that leaded fuels went bye bye. One of the ways one could deal with the lack of the high octane fuels their gas guzzlers wanted was to 'de-tune' the engine, basically adjust the timing to eliminate the knock that happened when you ran lower than required octane. You forced the spark to happen b4 the compression caused the ignition at unplanned times. This eliminated the knock at the cost of some performance. (very simplified explnation . . )

Today's engines do the same thing. If you run a lower octane the computer now SENSES the knock and will adjust the timing, usually at the cost of some performance, while preventing any damage from occurring. If you never push the car you may never notice the difference. If you have a GEN1 with a pulley and run lower octane ... why'd ya waste your money on the pulley?

Another example, my 79 has a 'tweeked' engine and the compression is fairly high; the ignition system is old school, with points and a coil and timing you can easily adjust. Mini documentation (owner's manual) says use high octane. For the first couple of tanks after I bought the car I always used 93 octane and all was well. One day, I decided to try some mid-grade - 89 - I put in about 5 gallons to the 7 gallon tank. Shortly thereafter the car was hard to start, knocked under any sort of a load and suffered run-on aka dieseling when the ignition was shut off, with the occasional backfire. I went back to high test - QUICKLY. And have not had a recurrence in 6 years . . . I could try adjusting the timing and run less octane, but I tend to use about 4 gallons a month so I think I'm OK.

**********************
bottom line is really to understand what "octane" means in relation to the internal combustion engine.

from: http://auto.howstuffworks.com/fuel-e...question90.htm

The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites. When gas ignites by compression rather than because of the spark from the spark plug, it causes knocking in the engine. Knocking can damage an engine, so it is not something you want to have happening. Lower-octane gas (like "regular" 87-octane gasoline) can handle the least amount of compression before igniting.
The compression ratio of your engine determines the octane rating of the gas you must use in the car. One way to increase the horsepower of an engine of a given displacement is to increase its compression ratio. So a "high-performance engine" has a higher compression ratio and requires higher-octane fuel. The advantage of a high compression ratio is that it gives your engine a higher horsepower rating for a given engine weight -- that is what makes the engine "high performance." The disadvantage is that the gasoline for your engine costs more.

 

I've asked the same question about our civic in other forums, and what I've always been told is that if it's a turbo, never EVER put regular in, it can damage the engine in ways I don't remember, but for non turbo charged cars, it should be fine.

 

MINI does have a stated policy that you will find in the owner's manual. You will generally be questioned as to what fuel you use in case of a fuel related warranty problem. Most dealers I have experience with will insist using less than the recommended fuel is harmful as well as reducing your performance.

In addition, if all that is not confusing enough, BMW hence MINI, recommends you use Top Tier fuel. There is a list of suppliers available which will include Shell and Mobil for two examples. Also, when you have a potential fuel related warranty problem, they will pull out their handy little fuel tester to see what content ethanol your fuel contains. If it in their opinion has more than 10% ethanol, they may well claim they are going to deny warranty coverage as that is the reason for failure.

Running Top Tier fuel of premium grade is a wise investment in your future well being. Keeping a few receipts showing this, could be even wiser.

 

Ok, I think I'm getting the picture. Premium gas only!

I learned a lot from this thread. Thanks.

El K.

 

In an S, as with any forced induction engine, you should be using premium. Yes, our cars have knock sensors and can pull timing for us, and likely boost too, but it's still harder on the engine and is generally a bad idea. While it is possible to run mid grade, it really doesn't make any sense, as the price difference isn't all that much to run the premium the S was tuned for instead.

 

Preignition makes hot spots on your pistons, and basically whacks the inside of your engine with a hammer. Neither of which is a problem if it happens just once or twice--engines are fairly hardy things, after all.

When it happens a lot, you can damage the pistons. I have seen holes blasted through the piston crown from "pinging". The pieces from that will go through the rest of the engine and make you very very very unhappy. Other problems can happen, but they typically mean small bits of metal going through your engine.

High-compression engines are more liable to pinging than low-compression engines are. Higher-boost engines are more liable than lower-boost engines.

The engine management system in a modern car can retard ignition timing and reduce the boost level when it detects pinging. (Or knocking. Or pinking. Or detonation. Lots of names for this phenomenon.) That only goes so far, and it will reduce the power made by the motor noticeably.

Some engines were built to run on regular-grade fuel (87 down at sea level, 85 up at altitude). Even some turbocharged motors. Some were built to run on super-grade fuel (usually 91), and can cope with lower-grade fuels. Others can only deal with lower-grade gas in the short term, and not necessarily all that well. It depends on a whole lot of factors--more than can reasonably be put in an owner's manual, and more than most of us can keep track of.

Bottom line: Follow what the maker recommends, usually in the owner's manual. If it says 89 is acceptable but 91+ is preferred, try both and see what makes you happiest.

 

30 cents a gallon more, assuming a 14 gallon fill up equates to an extra $4.20 in the end so not that much extra for peace of mind. If you have a Cooper S, premium is required due to the turbo.

 

When you drive off the lot with your new MINI S I'm willing to bet that the tank is filled with 89 octane mid-grade. So is the car you test drove, etc., etc., etc. .....

The sticker on the inside of the fuel door says "Minimum 89 Octane".

 

The sticker on the inside flap of my '07 R56 says minimum required 91 AKI (Anti-knock Index) which apparently is just another way of expressing (RON+MON/2). Amazing what you can learn!

Does the sticker on the inside of the fuel flap of your '13 model really say minimum required 89?

 

If you put regular fuel in the car, it will not perform or run like it should. I once had "bad" gas I bought on a long trip at a no-name gas station and my 08S actually sputtered and cut out a bit a few times until I made it through that tank. Regular gas will do the same thing, and you will also see reduced gas mileage and overall worse engine wear. Not worth it IMO, we only use 93 octane in our MINI's

 

Yes.

 

Anecdotally, people get 2-3 mpg better with premium gas, which is somewhere between 6-10% for your typical MCS.

Premium gas is ~.30 more than regular gas, which is a similar percentage difference. (.30/3.60, for instance)

Assuming 15,000 miles per year, 30/32 mpg (Reg/Prem), $3.60/$3.90 per gallon (Reg/Prem):

15,000/30*3.60= $1,800/year

15,000/32*3.90= $1,828/year


There are far too many variables to say these are representative of any individual car, but the idea remains. You save a LITTLE money, but tend to get a LITTLE worse gas mileage. In this reasonable case, one would save $28 per YEAR by using regular fuel.

 

my 03/2012 build 2012 cms all4 calls for minimum 89 (r+m)/2 which is "mid-grade"

i have noticed no difference between 89 E10, 91 E10 or 93 E10

i have noticed a huge difference using 91 E0 or 93 E0, 5-6 more mpg be it all city, all highway or mixed, smoother idle, much smoother cold start

ETHANOL IS EVIL!

scott

 

For an S, it's 89 or 93 (at least for me because nobody sells 91) for a Justa it's 87 or 89. And the difference is not 30 cents/gal., it's 15 cents or less. I get crappy gas milage because I have a lead foot and drive every day on US 19, one of the worst roads in the country as far as traffic goes. So, the extra octane not a priority. Now, in a few years when I trade up to a JCW Roadster, then it will be 93 all the time.

 

Yep, it absolutely is. Not only does ethanol "enhanced" gas lower fuel consumption but it is also extremely corrosive to fuel systems not designed specifically to handle ethanol. There has been talk in the last few years to allow E15 to be sold stateside which pretty much everyone (especially motorcycle riders, boat owners, and small engine enthusiasts) except corn growers is firmly against.

 

I don't get it. There is a shortage of corn due to the drought, so much so that there is talk about a shortage of BACON!!!!

Take it out of my gasoline and give me my bacon!