2008 base cooper, my mother in law's car. She puts regular in it even though it says premium on the gas door.
I want to put premium in it and reset the ECU so it learns to take advantage of the premium.
In my WRX, I just pull the negative battery cable and hit the brake peddle and bam, ECU is reset.
Is it the same for Minis? Any dangers, anything I should know?

 

The car has a knock sensor, so it has been adapting to the regular. Just putting premium in the car and driving it should adapt. You probably won't see much a difference if she is just using it as a commuter.

You need a quality scan tool to reset the adaptations.

 

I know about the knock sensor and figured the ECU retards timing for lower octane gas.
I was interested in trying to see if I could tell a difference b/t 87 and 93 oct.
So it's ok to continue running 87 in a base '08 cooper? Others do it all the time? Seems like it 'requires' it due to a high compression ratio?
I am currently dd the mini while my WRX is down. I drive 70 miles daily on the highway.

 

I personally run 91-93 because:
A. I can
B. It's factory tuned to run optimally on it
C. I drive spiritedly and damage caused by pre-det isn't really on my agenda.

Not to steer you wrong, but I have seen multiple customer cars that have well over 100k miles of original ownership that ran regular their whole life. They also were driven as nothing more than a commuter that never seen spirited driving or WOT runs.

Depending on where she's been fueling up at the ethanol content may very well have brought the octane rating up closer to 89-90 anyway.

 

MINIUSA said via email that my 2010 base was certified on 91 but would run without engine damage on 87. If you don't have a manual you can get a free PDF copy at MINIUSA.COM.