What fuel would you recommend using? I'm a newly owner of a 2012 CM S All4. The book says 89 octane minimum, but super premium (91) is recommended. Any suggestions/experiences would be greatly appreciated. Thanks!

 

I've always used premium - 91 or better.

 

98 the engine is much smoother

 

www.toptiergas.com. Have strictly used 91 octane toptier fuels for the last eight years.

 

+1 in the extreme, nothing less.

 

MINI USA told me via email that 91 is required to meet the mpg and emission standards published by the EPA. They say you can use 89 without damage to the engine when 91 is not available.

 

I also stay with premium gas, and top tier stations. The top tier designation has to do with the detergent in the gas, not the octane rating. If you want to see what happens when you use gas that doesn't have enough detergent, do a search for on this site for carbon build up, or walnut blasting.

 

I use 91 Chevron.

 

...or you can learn the hard way and use second rate fuel then spend what you saved by replacing the O sensor and/or other obnoxious expenses that could have been avoided. In the olden days it was called penny wise and pound (£) foolish.

 

The quality of the gasoline you use has nothing to do with carbon build up.
On the MINI Cooper S, fuel is injected directly into the cylinders, by passing the intake manifold and the intake valves. Because of this, oil vapor from the Positive Crankcase Ventilation system bakes onto the backs of the intake valves as it is not washed off by fuel, like it is with cars that have port injection, where the fuel is injected into the intake manifold and has to go pass the intake valves to enter the cylinders.

Dave

 

That's correct, the detergent in the gas will never reach the valves, but a cleaner burning fuel such as Shell V-Power can limit some of the carbon build up. More importantly, do not use 87 octane. Even though the computer will retard the timing, that few incomplete combustion cycle can cause carbon build up faster.

 

I'm curious why you would doubt the book and rely on the replies from people you know nothing about. I apply the theory that the people who wrote the owners manual are smarter about the subject than I am. For that matter I think they know more about it than any one who replies to this thread.

 

So like the 15k mile oil changes? Transmission fluid is lifetime guarantee? Makes sense:-). Yes I'm being sarcastic, I'm sorry. But some things the manuals are just plain crap.

Just use 91 or above in your MINI. 89 if you can't ever find 91 or above. You'll be happy you did.

 

I use She'll V Power premium and occasional regular addition of Techron or even better yet, Seafoam motor treatment

Tons of disciples who swear by Seafoam. All my cars, motorcycles, Vespas...

 

In mine manual they write= 95 ROZ minimal and for the COOPER S and JWC=98
91= possible if there is nothing else
This is an European manual, but engines are the same

 

They measure octane differently in Europe than in the US. US octane is a lower number than european octane ratings.

Dave

 

There is a 5 points difference= 98 EUROPE= 93 USA.So a Cooper S can not drive on 89 USA and have a top combustion.

 

I understand your point. With synthetic oil I don't know that the recommended 15k mile oil changes is necessarily wrong. However, like many, I change mine every 5k miles. The same thinking can be applied to transmission fluid. The older school a person is the more inclined they will be to change these fluids on a more frequent basis than the recommendations. Having fresh oil/lubricant more often than is recommended isn't risking internal engine damage while using improper fuel might.

 

Just run the highest octane possible for your area. Just remember that if you're cheap now you will pay for it later. In the end it's your ride and your money.

 

+1...that's my motto as well.

 

A neighbor, fellow CMS owner, just told me that I should be running Ethanol-Free gas, which is available locally. Any thoughts?

 

Unless the ethanol free fuel is 91+ octane, it is better to go with 91 or better octane fuel with ethanol. In my area, the only ethanol free gas is 86 octane.

The MINI's engine is designed to run just fine on gas with 10% ethanol. If you run ethanol free regular gas (86 0ctane) , the Engine Control Unit will dial back the spark advance and you will notice less horsepower.

Dave

 

First few months I had Lucy I lived in MS and could get 93 ethanol free so always ran it. Moved to GA and had to switch to 93 with Ethanol. only change wasvacdrop of about 40 miles per tank of fuel.

 

I don't think the local station has 91+ ethanol free, so we'll stay put with the good stuff! Thanks.