First, I apologize for starting a thread on a topic that I'm sure has been beaten to death, but, for the life of me, I can't figure out how to do a topic search.

O.K. here is the question -- owners manual says 91 octane, MA said 89 is just fine. He says that's what they use when they fill the car up for delivery. So, to the assembled wisdom here at NAM, what should I use?

 

On my 08 and 11s, it's been 91 but i think it's 89 when you absolutely positively can't find 91.
The gas filler door will be the last word.

 

I'd trust the engineers who dictated what is written in the manual and on the door cap over the guy who's only job is to sell you the car.

 

Do not use less then 91. By using anything less the computer will retarding timing to avoid detontation. Its not a good thing. If you use anything less ad an additive to boost octane.

 

93 all day! I usually fill at Costco so choices are only 89 or 93. Even at other gas stations i choose 93, in the end the only difference is a few dollars per fill, so why not use the best for the best?

 

91 is west of the Mississippi. Us east coasters have that jungle juice 93. Try to stay with 91 and above because you run the risk of detonation which will fry your engine.

 

http://www.toptiergas.com/retailers.html
http://pure-gas.org/index.jsp?
Find out what it costs to replace the O sensor then decide if you want to save a couple of bucks at the pump.

 

For those of you that want to learn a little more about the octane rating and what why it's important to the engine, please read this in its entirety ...

http://www.turborx7.com/fuel.htm

It's rather long but well worth the time spent!

 

93

 

Stopped by the dealer today to ask the octane question. My MA said to avoid Costco gas and only put Premium (91) Shell, Chevron or QuickTrip (in Arizona). He said Costco gets the bottom of the barrel as far as blends and additives goes. Also suggested that I put Techron in every 3K miles to keep system clean and avoid carbon build up. Thoughts? Suggestions?

 

I have worked in the refining/pipeline group for a Top Tier company and all gas from every refiner is mixed together in the pipeline unless the company has its own local terminal to supply the company owned stations. The difference is in the "additive packages" that each refiner designates. You have EPA & CARB minimum specs that all stations must meet. In essence the top tiers add more volume in an additive pack versus a lower tier gas, but all pipeline gas is generic..

 

People on car forums often recommend gas listed at www.toptiergas.com. Supposedly, they all have additives/detergents that help prevent deposit build-up. Among those listed are 76, Chevron, Conoco, Exxon, Mobil, Phillips 66, Shell, and Texaco, but there are others.

I used to use Techron (a detergent additive) occasionally until I discovered that it was already in the gas I was buying. Many gas companies apparently add that or its equivalent.

A petroleum chemist once posted a long description of the different fuel additives used by the various companies. He rotated every three tankfuls among three fuel brands in the top tier list to insure that his engines worked through all the desirable additives over time. No, I don't remember which brands were in his rotation because I didn't plan to be that compulsive. I do use top tier brands, however. Hope I don't find it's all a myth on Scopes.

 

Wish I could remember the results of my organic chem lab years ago in which we took samples from gas stations and actually tested the octane - but I seem to remember some measured ratings being less than advertised.

But let's say that the difference between 91 and 89 is 20 cents. That means a ten gallon fill-up would cost $2 more to ensure the higher octane edge. That's insuring your investment for what you would spend on a donut and a cup of coffee - and perhaps only once a week. A no-brainer - I'll skip the apple fritter. I never go for less than the top octane at any pump.

 

Wow...your MA must have access to some deep source information from within Costco. But I doubt it.

 

I wish there were top tier gas stations within 100 miles of where I live so I have to live with the 93 that flows from whatever station I can find.

I usually fill up with BP since it's recommended in the owner's manual(which is odd since it's not a top tier gas provider). Then again, I've only put two tanks of gas into my car. lol

I don't understand why someone would skimp on octane to save money then turn around and buy a bottle of booster. Unless someone changed the rules of math; $.20 x 13 gallons is cheaper than a $5 bottle of octane booster per tank.

 

If you buy it by the gallon on Amazon.com, it is cost effective (.60/15 gal) but you either have to put it into small bottles or use it when you get home. It would be pretty good if you couldn't find 91 octane and were too cheap to buy 93.

I'm still looking for stations that sell 91, until then I'll be using 93 unless I'm just topping off in which case mixing in some 89 will still keep the gas in the tank at the 91 minimum.

 

Oops! My bad, the Lucas octane boost is $6.00, the fuel treatment is much cheaper.

 

Andrew: BP is British Petroleum, so it's an appropriate fuel for the MINI.

 

They are being cheap and they shouldn't do that. MINIUSA wouldn't be happy about it if they knew.

BMW/MINI engineers tuned the engine based on 91 octane. The engine will self adjust to lower octane gas, but there may be some loss in performance or mileage.

 

My gas cap says 89 minimum, and to use fuel additive regularly. No specification on what additive.
OM says 89 AKI minimum, but recommends 91AKI, and recommends 93 AKI for JCW.

 

BP used to be a Top Tier gas.

BP let that lapse shortly after Deepwater Horizon. I guess they had more important expenses to address rather than maintaining the Top Tier designation. No doubt, their gas formulation is the same or better than it was when they were listed as Top Tier.

 

The Federal Trade Commission's take on octane:

"Are you tempted to buy a high octane gasoline for your car because you want to improve its performance? If so, take note: the recommended gasoline for most cars is regular octane. In fact, in most cases, using a higher octane gasoline than your owner's manual recommends offers absolutely no benefit. It won't make your car perform better, go faster, get better mileage or run cleaner.

Your best bet: listen to your owner's manual.

Regular octane is recommended for most cars. However, some cars with high compression engines, like sports cars and certain luxury cars, need mid-grade or premium gasoline to prevent knock."

The posting goes on to say that each state has it's own definition of what constitutes "premium" and, obviously, the best solution is to actually look at the octane number and not the word description to make your selection.

http://www.ftc.gov/bcp/edu/pubs/cons...tos/aut12.shtm

 

MINI manuals say 91 is "highly recommended".

 

I use 93. Rather be safe and spend the extra 10c/gallon....

 

All we have locally is 91 so when we travel and have a chance to get 93, the li'l guy just trips out.