Anyone feel the need to put Super Unleaded (91 or 93 octane) in your tank?

 

Uh, yes. Definitely yes.

 

I have no pings, no knocks, and the manual for the 2007 says 87 is the minimum. Am I asking for trouble, or is it purely a performance issue?

 

The 2010 manual says 91 is highly recommended but it doesn't say why.

 

Because you have an 11:1 compression ratio....lol

Just use premium people...it only comes out to be a few dollars more anyway...why risk it?

 

"why risk it?"

See post #3 for relevance. What are you risking if the manual says you may use 87?

 

For FI engines, higher octanes are probably geared towards performance. FI engines responds to higher octane better? With N/A engines it might not make much difference. For .30 cents difference from 87 to 93, i always go for 93 (shell exclusively unless no choice when fill up is needed).

 

Looking at your sig I see you have a N/A Cooper, so thats probably why you can get away with 87 Octane and not feel or hear pinging/knocking. However, I believe that the non-turbo engine is NOT direct injection, so 87 octane + 11:1 compression ratio isnt probably the best idea, even though you can't hear any pinging or knocking, it doesnt mean that it's not happening in your engine and your ECU might even be pulling timing to compensate. In your case, I would recommend running a higher octane.

 

Both the turbo R56 and the blown R53 require 91 or better fuel. The base model motors or normally aspirated motors runs on 87. Both "S" motors run much higher cylinder pressures and temperatures so they need a more stable fuel to prevent detonation. Most people don't realize that the higher the octane rating a fuel has... the harder it is to ignite and more stable it is.

All the motors have computerized engine management systems that will adjust the ignition timing (basically, de-tuning the motor) to compensate for inferior fuel quality, but this is not something you want to happen on a regular basis.

I would agree that the cost associated with using 91+ in all cases is not a huge amount of money, but I also agree that your money is not my money and I'm not one to tell anyone how to spend their money.

Cheers!

 

It's just rare that I see people getting away with 87 Octane in a car with 11:1 compression ratio. Even if the ECU is compensating for low ocatane fuel, it has to register a knock event to pull timing, so it IS potentially damaging, regardless of whether the ECU compensates.

 

1st gen NA cars say to use 91 or higher.

 

Well said

 

I did not know that all the 1st Gen cars require 91 fuel. Good to know, thanks

Dan

 

The 2010 manual says 89 is the minimum for S and Works. It also says: "If you use gasoline with this minimum AKI rating, the engine may produce knocking sounds when starting at high outside temperatures. This has no effect on the engine life."

 

You probably won't get as good MPG with 87 octane so the price savings will be offset by using more gas.

 

Why be so cheap??

 

+1.

 

No doubt about it, I put 93 in EVERY time. We have an R53 and R56 and both get this gas from BP and Exxon every time and get better gas mileage because of it. The car literally feels sluggish and runs like crap o regular gas IMO

 

It'll work fine until it doesn't and then you'll get the finger when something goes wrong and you need warranty work done. Maybe your warranty already ran out, then you better start setting money aside for a huge repair bill down the road...

 

This is NOT a good idea.

I've had a customer that did this with his MINI. It made it 42k and died. Burnt valves, carbon build up in the head really bad, and cracked piston rings. Engine lost enough compression on all cylinders it had to be replaced. Cost of Engine and labor with parts $7000

Now lets do the math on what the premium gas would have cost.

42,000 miles, if he got 24 miles to the gallon, he would have used 1750 gallons of gas, now multiply that by the 30 cents, It would have cost him $525 more for the premium fuel. Difference of $6,475.

You make the decision on is it worth the risk??

 

My 2008 regular Cooper, states 91 on the gas door. The book says 87 is OK, as long as it's not used in hotter climates. I knew it called for 91, and in my brain, I figured 91 was the middle grade, since premium is 93 here. As I was filling it with 89, I read the gas door seeing the 91 label, and ran for the manual to make sure I didn't just do something bad. It's cold here now, so I didn't worry as much as I did before reading the manual. This tank of fuel, I got the same mileage as the first tank with Premium, supposing it was Premium, since I just bought the car. Today I filled with 93, so we'll see if there is any difference. I do agree, going with lower than the recommended is risking lower performance and possibly some damage.

 

Well said, you would be very surprised what minor pinging and knocking can do to an engine over time.

 

you can get drunk on rotgut cheap whiskey too, but I don't recommend that either. Gas is cheap. If you wanna save money buy a cheap POS car, not a Mini.

 

Interesting, most of the gas stations here in Minnesota provide 91 octane as the premium (87 is reg, 89 is middle). Some have 92 & 93 (and a handful of stations have non-ethenol premium). We always have a 10% blend.

The gas cap door says premium required. End of story. Premium goes in.

 

MINI stikes again. My gas cap also has a (small) label that says 91 AKI minimum and advises to see the manual for details. As stated before, the manual says 87 AKI minimum for the Cooper and 89 AKI miniumum for the "S" and John Cooper Works.