I have a mini with a 17% pulley on it. I was wondering about the minimal octane that could be used in the car without damageing the engine. I know the FIM recommends 91 octane. I can only find 87, 89, and 93 octane. The difference is price here is around 20 cents, so if I go with 89 I can save a few dollars. I'm sure the price is going up, but I don't know if the difference in the cost between octanes will broaden or not.
If I run too low an octane I think I'll get an engine knock. Would I be able to hear this or feel it?
I don't want to damage the car to save a few bucks, so I'm just trying to gather info.

Also, I know that octane will not improve the speed of a car that can't use it, but will differences in octane make a power difference in the Mini S? Anyone run speed trials with difference octanes up to and including racing fuel.

REHutch

 

>>I have a mini with a 17% pulley on it. I was wondering about the minimal octane that could be used in the car without damageing the engine. I know the FIM recommends 91 octane. I can only find 87, 89, and 93 octane. The difference is price here is around 20 cents, so if I go with 89 I can save a few dollars. I'm sure the price is going up, but I don't know if the difference in the cost between octanes will broaden or not.
>>If I run too low an octane I think I'll get an engine knock. Would I be able to hear this or feel it?
>>I don't want to damage the car to save a few bucks, so I'm just trying to gather info.
>>
>>Also, I know that octane will not improve the speed of a car that can't use it, but will differences in octane make a power difference in the Mini S? Anyone run speed trials with difference octanes up to and including racing fuel.


This has been discussed at great length. Perhaps you can use the "search" function to help with your research. I use 93 octane in my MC but I'm almost positive it's a waste of money and 87 octane would work fine. MINI's are sold all over the world and octane availability varies from country to country. To cover their liability BMW just recommends a high octane. This may be overkill but it protects the company and gives them one more thing to blame failures on if you use a lower octane, justified or not.

Besides, people tend to think if you pay more for something it's just gotta be better.



R.E. Stancliff Sr.

 

Since you have a pulley I do recommend the premium. What I have been doing with great success so far is to alternate fill-ups between 89 and 93 octane fuel, while not going much below 1/3 tank before refilling. Mixing the fuels gives an approximate 91 octane level. No difference noted in performance or fuel economy!

 

I read several years ago that cars made in Europe have a recommended octane rating that is actually higher than what is needed because of a different rating standard. The European octane standard is based solely on MON while the American standard is the average of MON and RON. Since RON is typically a few points less than MON, the overall average (and octane rating) is brought down. For example, our 88 is the same as the European 91 since the MON is 91 but the RON is 85, thereby averaging 88 but being the EXACT same gas as the 91 in Europe.

Is this taken into account when the cars are imported over here? I remember wondering why my the Land Rover got less quoted gas mileage in the American handouts than the British ones. I figured it was because of all the smog junk they put on the cars until I found out that a British gallon has an extra pint!