Ask MF: Is 87 Octane Ok?

glangford Dec 16th, 2008 Link

I have a R56 cooper, never ran anything but 93 octane. It has a higher compression ratio than the turbo charged S. I wish I could find someone in the top tier brand that sells 91 (recommended), but unfortunately the only 91 I can find is off brand.

Bwana Yak Dec 16th, 2008 Link

I’ve been running regular in my ‘06 MCS for the last year or so (20-30K miles), and I have noticed about a 5% decrease in fuel economy and perhaps the same percentage of decrease in power. The engine doesn’t feel quite as smooth and I occasionally hear some minor pinging when I get a heavy right foot or climb a steep hill. Other than that there hasn’t been any negative effect.

I consider the savings of using regular gas to be a wash when weighed against the decrease in power, reduced fuel economy and reduced driving enjoyment. Now that cost isn’t as much of an issue I’ll probably switch back to premium fuel.

C4 Dec 16th, 2008 Link

I never understood the logic behind buying a $25K+ auto and going cheap on the gas. If the manufacturer says you should use 91-93 octane, then that is what should go in the tank each and every single time.

Saving a few cents per tankful is nothing but a false economy. You are damaging your engine and increasing carbon build up deposits in your intake valves. Don’t believe me? Go and take a look inside a torn down enhine that has been feed regular gasoline most of its life. Its scary.

Folks, you can give up the latte, that extra cigarrette pack or even that Netflix subscription or those useless extra texting cellular charges.

But your car does not deserve to be fed the cheap stuff just to save a few pennies a month. Not worth it.

Donovan Dec 16th, 2008 Link

I don’t think the literature says it is “ok”, just that you can.

charlie Dec 16th, 2008 Link

I only put 93 octane in my beast and it runs smooth , You will notice a power decrease with the 87 octane and less fuel econmoy but like C4 said Why put the cheap stuff in your Nice car that requires it ? To save a couple pennies ? ask yourself Why !

rdelar01 Dec 16th, 2008 Link

STOP THE MADNESS! Death before 87 Octane!

mike c. Dec 16th, 2008 Link

I ran a tank of regular in my R56 MCS and noticed a very real drop in power. That and what I’ve read about less fuel economy stopped that experiment. Here in the Bay Area I only get 91 octane for supreme and only top tier gas.

Craig Dec 16th, 2008 Link

Let’s look at the numbers shall we? If you drive your Cooper 15,000 miles/year and have an average of 32mpg, that works out to 468.75 gallons of fuel. In my area 93 octane costs about $0.25 more than 87 octane. So all else being equal, you would save a tidy sum of $9.77 per month! If this amount breaks the bank for you, then you have serious financial problems.

Tom Dec 16th, 2008 Link

Running anything other than what is recommended will decrease MPG’s as well as gunk up your injectors and valves. This is a sophisticated engine both in the Cooper and Cooper S Turbo. Do the calculations and add new injectors after your MINI Maintenance Programs ends as well as an engine overhaul in the future. Also just expect to try and start your MINI several times as it will not ignite properly anymore. Want to run 87 octane – go get a Toyota Matrix. Put some bonnet stripes and rally lights on it. Go for it.

Chad Dec 16th, 2008 Link

But if the specifications call for 91 octane, could you not just fill up a third of the tank with 87 octane, and top off with 93 octane? If the price difference between 87 and 93 is large enough, it could make it worth the process.

Dr Obnxs Dec 16th, 2008 Link

Really, it depends on how you drive and how much gas costs. If you’re very soft on the pedal, don’t rev too much, and gas is cheap, you’ll save money with the lower octane gas. If you accelerate hard, go to higher revs, or gas is very expensive, then it saves money to get the better gas.

If responsiveness and performance are what you want, get the higher octane gas.

There isn’t a “right” answer here. There’s what’s best for how you drive though….

Matt

glangford Dec 16th, 2008 Link

I’m not sure. I don’t rev, mainly living in my R56 MC between 2 and 3K rpm. I’ve never used anything but 93. Even though I’m ’soft on the pedal’, I feel that the 93 helps to make the car responsive at low RPM when it needs to be. It would seem that use of lower grade fuel would take away some of the advantage of the MC’s flatter torque curve in the R56.

iNomis Dec 16th, 2008 Link

I run mostly 87 in my 07 MCS. I’ve run 93 in past cars that called for less to make them run better. I have no problems putting in 93 if it is needed. I have not measured or felt much effect in the R56 MCS when I do use 93. I’m sure there is some. Good 87 won’t hurt, give it a try and make an informed decision.

As far as I know octane alone has nothing to do with gunk, carbon, dirty injectors etc. If you can point to some facts that it does I would like to see them.

John W. Dec 16th, 2008 Link

‘04 MC with CVT, 60K miles. I have been running medium grade fuel for a better part of 2 years. No problems encountered as far as pinging or lost of power. My fuel ecomomy is averaging 32mpg which is the same when I was running premium grade.

John W.

C4 Dec 16th, 2008 Link

iNomis, please explain to me why saving $10 bucks per month by using 87 octane is a good thing for your car and pocket book?

Sorry but your logic makes ZERO sense to me.

C4 Dec 16th, 2008 Link

iNomis, lower octane gasolines lack the detergents to keep your valve intakes free of gunk build up. Hey its your car and your money.

Just don’t complain when your engine starts to have performance issues past 100K miles.

C4 Dec 16th, 2008 Link

Top Tier Gasolines:

http://www.toptiergas.com/index.html

paul Dec 16th, 2008 Link

Garage near where I work has a price differential of 65c right now between regular and premium unleaded :(

I’m as far from a mechanic or engineer as you can get but surely if MINI says the car can run on regular, then it can run on regular. Why would they say it if it wasn’t true? Similarly, why wouldn’t they put “you can but it will gunk up your engine if you do” if they thought it did?

I always put in premium since that’s what is recommended, but I’ve always assumed that’s for best performance, not because I absolutely had to.

iNomis Dec 16th, 2008 Link

C4, Any brand of gas will likely have the same quality across all octane ratings. The myth that lower octane fuel has lower detergents or quality is one thing this post should highlight, not reinforce. Your link does not even mention octane and in fact seems to point out all of our gas is bad. Though I do thank you for it as I would never had known “Turkey Hill Minit Markets” was top tier gas!

C4 Dec 16th, 2008 Link

Guys, saving $10 bucks a month is worth it to you? Geez!!! I am a cheap bastard but some of you take the cake!

Gazelle29 Dec 16th, 2008 Link

When I sold MINIs, I would always wonder why people made such a big deal about the 91/93 octane gas. The price is only $.20 a gallon more. In a small car, that is only $2.50 a fill up more. If you spend this extra cash, you will have better economy and the car will run better. Who knows if the engine will last longer or not but, if the manufacture says to use high grade, use it. If you can’t afford the couple of dollars extra, don’t buy the car.

Aaron Dec 16th, 2008 Link

I use 91 octane, usually from Shell. Can’t get 93 out here in CA. I know that’s not helpful for the poster, but I have never done the experiment using 87 octane to check my efficiency.

As for saving $10 a month, it’s not a lot of money, but if there REALLY is no difference in the long term, that’s $600 over the 5 years of a car loan. For me, that would be well over one month’s loan payment. I can see why someone, perhaps somebody on a lease or someone who doesn’t plan on owning the car beyond 4 years would see that saving $120 a year is probably about what they’ll earn annually in interest on a $5000 savings account, at today’s rates, so it’s worth it.

Does the on-board computer keep track of the octane rating of gas you’ve used in your car over the years? If not, what’s stopping folks on a lease from saving the cash and using 87 octane and filling up with Vpower once in a while to help clean the engine? That is…IFF the MPG efficiency is about the same. If somebody doesn’t plan on having this car past 100K miles, what’s it to them? I doubt it affects the re-sale value of the car much as I suspect people don’t bother to ask about what the car’s been fed, and if they do, I would be surprised if the seller told the truth. I started taking records of each tank fill up about a month after I bought my car new (wanted to track the fuel efficiency), but I doubt many others have such records, unless the car is a business expense.

Ken Dec 16th, 2008 Link

Out here, 89 octane is about 10 cents/gallon more than 87, and 92 or 93 is about 16-18 cents more than 87. I alternate fillups between 89 and 92 or 93 (depends on the day, same station, sometimes 92, sometimes 93, go figger).

So, I average about 12 cents per gallon more than 87 and average about 91 octane. 8 percent more for 5-6 percent better mileage? Sure, sounds close enough to a wash to me.

Albert Dec 16th, 2008 Link

In Europe cars are tested at 91 octane (stantard for the EU). I filled my car once with 93, then every half tank I fill up with 89, the next half tank with 93, and so on. The mix avergaes 91 octane fuel or so and saves some money, if that’s the goal.

r.burns Dec 16th, 2008 Link

No in Europe it is 95 the standard ! and 98 is recommanded for the MCS and Works ! you have to fill up with these unless you don’t reach the entire power of masterpiece/motor

glangford Dec 16th, 2008 Link

The ratings are not the same in Europe and the US.

“In most countries (including all of Europe and Australia) the “headline” octane rating, shown on the pump, is the RON, but in the United States, Canada and some other countries the headline number is the average of the RON and the MON, sometimes called the Anti-Knock Index (AKI), Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2. Because of the 8 to 10 point difference noted above, the octane shown in the United States is 4 to 5 points lower than the same fuel elsewhere: 87 octane fuel, the “regular” gasoline in the US and Canada, is 91-92 in Europe. However most European pumps deliver 95 (RON) as “regular”, equivalent to 90-91 US (R+M)/2, and some even deliver 98 (RON) or 100 (RON).” 95 in Europe is about 90-91 here.

robble Dec 16th, 2008 Link

You want to save money on gas? Buy a bicycle.

Don’t cry when the service department tells you your service engine soon light is not going to be covered under warranty because you didn’t use the gas the label on the gas cover says to use.

Dave MacMini Dec 16th, 2008 Link

If your owners manual “requires” premium fuel, you should use it, but if it “recommends” premium, a lower octane will work fine. We have used mid-grade fuel in all our MINIs, one Cooper and two MCSs since 2002, and have had no problem. My service advisor told me that BMW had indicated to him that the Cooper (a 2002) would actually run better with mid-grade than with premium, and that is what we have used since we got that advice. BTW, if you have a car that the manufacturer says should use regular gas, you are absolutely wasting your money if you put premium in it. You will not get better performance or mileage. However, if your car is designed to run premium, you might take a small hit in performance and mileage by using regular, but in most modern cars, the on-board computer will compensate for the differnt octane, and there will be no damage done. If you are getting pinging, move up one grade and see what happens.

Second to none Dec 16th, 2008 Link

I wouldn’t use 87 in a cooper. In an S model, yes. The difference is the Compression Ratio. The Cooper S has a lower compression ratio than the Cooper version, in both the R56 and R50/53. If you are not driving in boost, you won’t have a problem. If you are driving in boost, you can get away with it in very cold temps provided you are not trying to do a track day, and you are running the stock ECU software. The reason you see a decline in MPG with the coopers is because your engine is retarding. Your spark timing is retarding itself so the fuel is given less time to burn in the combustion chamber (think ignition at 5 degrees BTDC instead of 30 degrees BTDC example of ignition timing) Should you use it or not is your personal decision. I ran my R53 no pulley or anything on 87 and it ran great. 10psi stock, on 87, no problem. After some modifications, and GIAC, it would ping (like ticking) at anything over 5psi. Mostly from the software i’m sure, as a/f ratios will change the likelihood of autoignition (pinging) in the engine. With my mild economical driving style, I run 87 in the winter. In the summer I run 93 or 91, as the hotter intake temps plus compressing before the spark make the difference between auto igniting at 5 degrees BTDC or 30 degrees BTDC. Look into the “gas law”, not “boyles law” on google or wiki or whatever you’d prefer. Boyles law does not account for the heat that the vaporized fuel absorbs, if anyone is curious. Email me with criticism or questions. I like these arguements!

Woofcast #279 | whiteroofradio.com - The MINI Cooper Podcast Dec 16th, 2008 Link

[...] be landing and we think it’s going to be happening at AMVIV in ‘09. We also revisited the octane debate one last [...]

MotoringFile » Archive » White Roof Radio #279 Dec 16th, 2008 Link

[...] be landing and we think it’s going to be happening at AMVIV in ‘09. We also revisited the octane debate one last [...]

Badburro Dec 17th, 2008 Link

Saving $2.50 per tank is not worth it people. Give up your latte for the day and your MINI will thank you for it.

If you’re really thrifty and want to save, why not get your 87 octane gas from Arco? (could anything be worse???)

Craig Dec 17th, 2008 Link

The difference is the Compression Ratio. The Cooper S has a lower compression ratio than the Cooper version, in both the R56 and R50/53.

That doesn’t hold as much water with the R56. The R56 Cooper has a CR of 11:1 and Cooper S has 10.5:1. The R50 had 10.6:1 and the R53 8.3:1.

If anything, fuel grade should be more important in the R55/56/57.

Chris Lamb Dec 17th, 2008 Link

Craig,

those compression ratios are with NO boost! On the road there IS boost.

FWIW is use 98 RON UK fuel in my MCS.

Woofcast #279 | donburnside.com Dec 17th, 2008 Link

[...] be landing and we think it’s going to be happening at AMVIV in ‘09. We also revisited the octane debate one last [...]

nickminir56 Dec 17th, 2008 Link

Why buy a nice car and make it less enjoyable for a mere $2.50-$3.00 per tank?

Anyway, for people go that far to save a few dollars: regular maintenance + low rolling-resistance tire + hyper miler technique save you a lot more.

Mk1 Dec 18th, 2008 Link

Hi-larious. Do you gas-misers also only shower once a week, to save the 20 cents per it takes to heat the water each time? Do you buy your clothes at Goodwill to cut your wardrobe costs in half? Do you only do laundry once a month, and wear each pair of your jeans at least week, to save that extra $2 of laundry detergent. Do you dumpster-dive behind Safeway for your lunch to forgo paying $1.50 for that take-out sandwich? Sounds like obsessive-complusive disorder to me. If you can’t afford the extra few bucks a week for premium gas – you bought the wrong car.

iNomis Dec 18th, 2008 Link

What is funny, is why anyone would laugh at and ridicule someone for posting about their own personal experience saving a significant amount per gallon (currently 1.49 vs 1.89) using an APPROVED fuel that makes no noticeable difference in how their car runs. The motivation for it escapes me. I can understand why someone may want to (and MINI’s recommendation to) run premium to get the last 3%(?) of power or milage. I just can’t understand the fervor to get everyone else to feel it’s is the only rational choice.

C4 Dec 18th, 2008 Link

And I can’t understand the cheapo bastard mentallity either when it comes to saving a measly $10 per month in gas and decreased performance.

These are the same folks that cry in the service department when they are presented with the repair bill.

Brian Dec 22nd, 2008 Link

If you buy gas from Chevron, Shell, Mobil, BP etc, there is no difference in the detergents between octane. R53 runs fine on any octane that I have put in it. No ping ever. I’ve had my car for over 4 years.

Nathan Dec 23rd, 2008 Link

I gotta say, I’m with C4 on this one. False economy.

Craig L Jun 16th, 2009 Link

The detergent argument is bunk these days if you get gas at most any reputable station. I use Quicktrip and it’s the same detergents/detergent lvl.

You can tell the car obbsessive in these replies and you cannot argue with them. They eat, sleep and breathe their cars so it is understandably important to them.

To those that keep tossing the $9-$10 a month thing out there…do you live 5 miles from your house???

With my commute (and many other people living in Atlanta) the difference in 87 and 93 octane breaks down to about $40 a month.

$500 a year is worthwhile reason to investigate 87 or 89 octane gas in the newer 07+ engines.