Regular or Premium Gas - which one is recommended for R56 MCS?

 

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The suggested thread is from 05 when the new engine was not available. That said, I'd still use premium. The manual for the 07 mini (with new bmw engine) says minimum octane of 87. The new engine can run on 87 and has anti knock sensors to allow that, however, the recommended octane is still 91. Performance and fuel economy figures are quoted for premium 91 octane fuel.

 

I cannot see this engine not running its best at anything less than 91 octane. The regular engine has a 11.0:1 compression ratio and the turbo-charged version starts with 10.5:1.

Those are some pretty high compression ratios. I am sure the engine will run with 87 octane, but you can bet the power will drop off sharply as the engine control unit tries to provide a profile which will keep the engine running cooler (i.e. retarded timing, less lean air/fuel ratios...).

 

VERY INTERESTING

 

I'll be using premium in my Cooper...using "the good stuff" actually helps your MINI get better fuel economy. Buy from a "top-tier" vendor if you can, too.

As a side benefit, you can avoid the tedious small-talk about "which station has the absolute cheapest gas" and then drive miles out of your way to procure the same. Save money elsewhere...but take care of your MINI!!!

 

This is directly from the 2007 MINI Cooper manual.

Require Fuel
Super Premium gasoline/AKI 91
This gasoline is highly recommended. However, you may also use gasoline with less AKI. The minimum AKI Rating is 87.

If you use gasoline with this minimum AKI Rating, the engine may produce knocking sounds when starting at high outside temperature. This has no effect on the engine life.

 

'Recommended' and 'minimum' are not the same thing. Go with 'recommended.'

Zip

 

As the owners manual states and the reasons Skuzzy mentioned, Im only using premium. Turbo charged engines should not be using lower grades of fuel. Besides, is it really worth poorer performance to save a couple bucks when you fill up? Stick with the good stuff your car will thank you for it!

 

As long as you only use reputable gasoline you will probably be OK as the manual says. Performance/power will be better with premium and maybe the higher the octane the better(Didn't I read a thread about this specifically to the new engines?). My past empirical experience (unlike some others) is that some engines do in fact get better highway milage with premium even when they do not require it, though not enough to offset the entire price difference.

Based on all that I will probably try a 1/2 tank of 87 when I'm near empty at some point after break-in to see how it does. Can always top up with 93 if the results are not satisfactory. Mid grade 89 seems like a complete waste of time.

 

Has anyone tried 87 on their Mini Cooper yet?

 

I've used 104 octane unleaded in my R53, it ROCKS!

Don't be cheap, low octane fuel gives your engine the chance to knock, and knocking breaks pistons. If MINI says 91 [R+M]/2, do it, it won't kill you. Yes it sucks you have to pay a whopping $2 more per fill-up, no there's no oil company conspiracy, it's just chemistry. High compression engines, and turbo & supercharged engines need higher octane than those "mere" normal engines. If you want to snob it up, think of it as "your MINI is too good for that 87 octane stuff". LOL

 

the new cars and see if they pull timing. That's the only way to know how much of a hit is being taken for lower octane.

Matt

 

I believe owners manual recommends premium 91 octane, although it also says you can use as low as 87 octane. 2007 owners manual is now available on-line in owners louge.

 

Yes Matt, that would nail it down for sure. However for the vast majority of people out there, the best advice is to heed the recommendation of the manufacturer.

 

I'll be using premium even if the manual says minimum 87 in my S.
It is forced induction after all. If I wanted less power I would've ordered a cooper.

Luckily I can afford an extra $80 a year to give it the best stuff.

 

go ahead and log gas milage with the crappy gas. I think you'll find that it drops a higher percentage than your cost savings....

And the Mini reccomended level still isn't good enough on the SCed MCS.

Matt

 

It is more than just the cost of fuel versus the mileage benefits. It is also about long term engine life. That one knock/detonation could cost you thousands of miles of trouble free motoring.

It's just not worth the risk.

 

for the supercharged cars, they run timing retard at WOT from the factory based on the detection of the onset of knock. Catastrophic predetonation can ruin a motor instantly, but our cars are tuned on the edge (over the edge?) of knock onset so that they can take advantage of higher quality gas without risk from lower quality gas. The detection system is very sensitive and detects knock onset long before it's dangerous to your engine. But it's a conservative tune, and pulls a lot of timing quickly so performance suffers more than it should in the name of safety. This is absolutely true for the R53, and I think for the R50, but I haven't logged it. Don't know about the new cars, but this is more of a tuning philosophy, so I expect it for the new cars as well.

Matt

 

nope, I won't ever know the difference because I won't put the cheap stuff in.

 

What do you think mid grade gas is? They mix the regular with the premium. (87+91)/2=89

For the 2007 minis, whatever they reccomend, put in. But there is no need to go higher than what they recomend. In fact, putting higher grade gas than what is recomended does not benefit your engine at all, and can have minor detremental effects.

 

If you're referring to a totally stock engine, I'll agree with you. The higher knock resistance will not help anything if there are no knocking issues. However, on highly modified engines with greatly increased boost and/or timing, higher octane is absolutely necessary to prevent engine damage. Most enthusiasts aren't going to go use anything beyond 93 octane, so most bolt-on tuners wrap their tuning efforts around available 93 or 91 octane unleaded.

 

I keep reading this and it's a fiction of the past! Cars now (at least good ones like the Mini) have knock sensors that are used to control timing advance. This is done by detecting the onset of pre-ignition before it becomes a problem. To make the car work pretty much everywhere, they put a decently agressive tune in the car and let the knock sensor handle the safety. This means that you can usually get benefits in performance for at least a couple of octane higher than is reccomended.

The notion that "extra octane is a waste" is true only if

1) you put in much, much higher octane than is reccomended with a knock sensor governed car.
2) you have an older car or one that doesn't have knock sensor based timing retard.

The roots of the this dogma is that cars USED to be equipped from the factory with a fixed timing, and no knock detection. So you put in crappy gas you got pinging. You put in good gas you didn't. Any octane past what was needed to stop the pinging was "extra" and wasted.

Now, not all cars have knock sensor governed timing, but all will. This is because the engine efficiency goes up with timing advance. Using knock governed timing control will allow for the most efficient burn of whatever gas is being used, and this ups overall gas mileage and lowers emmissions.

Sorry if I seem a bit rough here. But about every 20 minutes or so (very exagurated) a new thread pops up, or an old one comes back to life, that repeats the notions of the past as principles of operation for a car that is way more advanced than the machines that created the dogma. So then I have to choose to post again, or let the errors perpetuate again.

Matt

 

I feel your pain Matt! The same can be said for people clinging onto myths about breaking in engines; thinking that following the owners manual and taking it easy for a 1,000 miles will make the engine last longer when 1k miles in you suddenly shock the engine and the rings aren't sealed to the lands or the bore. *sticks out tounge in disgust*

I think for most people, they only have 3 octane choices, regular, mid, and premium. Most people, even enthusiasts, aren't concerning themselves with 100 and 104 unleaded or 110 leaded, let alone out there stuff like C16, E85, or better yet, nitromethane!

An example where the old octane myth is true is my 1st gen Miata. It has fixed timing and is stable with 87 octane. If you managed to find old school 85 octane, it'll ping and run like crap. Since there's no knock sensor, anything over 87 ISN'T GOING TO HELP power, since the engine isn't knocking, and can't adapt it's timing based on "pushing timing to the edge" like the R53 MCS and the Dodge SRT-4 do.

Bottom line here people: Run premium unleaded in your MINI. If you're too cheap to put 91 or 93 octane in, then expect reduced performance because the ECU will detect knock and pull timing. It's really that simple.

 

Whoa, no need to call me names, Matt

Actually, cars used to have distributors that could be easily adjusted to advance or retard your base timing. So when folks wanted to get more power from their sports cars, they would:
1) replace all your ignition consumables (points, cap&rotor, plugs)
2) gap your points
3) make sure you had the best fuel you could get
4) advance your timing well beyond factory spec until it started knocking with consecutive runs
5) back off slightly under that point of knock
This technique also works on old cars converted to simple "electronic" ignition. And a car tuned this way was intollerant of bad fuel or lugging the engine in the extreme (wrong gear up a hill for example)

I think the point you were making is that before good knock sensing systems came along, cars went through a period of don't touch tuning, and that was a time when even a stock car could suffer from the wrong grade of fuel.