Our 2014 Countryman S only has 950 miles on it (took delivery of it about 4 weeks ago) and she just called me from the gas station: "I just filled the mini with regular unleaded 87 octane by accident!"

I told her not to worry, just to make sure she remembers to use premium 91 octane (we can get 93 but it's not that prevalent around here) from now on. She said the tank was a little less than 1/2 empty according to the gauge, so it had about 6 gallons of 91 in it when she topped it off with the 87.

It's no big deal to use 87 just one time, is it? I also suggested she top it off with 91 when it's at the halfway mark again... not wait until the tank is almost empty...

 

Should be fine.

 

It shouldn't be an issue, especially if the weather hasn't warmed up over there. With the knock sensors the worst you should experience is reduced power, though you will probably not notice this in day-day driving (tell your wife to avoid doing WOT runs <g>). If you're really concerned you can buy a bottle of octane booster to put in the tank.

 

sounds like you have the right idea. MINI's are made to be able to run cheap stuff in a pinch(ie you're in middle of nowhere and thats all you can find) Just no overly spirited driving until you clear it out.

 

I have used regular gas a couple times in rural areas where I couldn't find premium. It's no big deal, you'll just lose a little performance and I surely wouldn't suggest making it a habit.

 

If it wasn't diesel she will be fine :-)

 

Just throw in a can/bottle of octane booster.

 

Update: Countryman is running fine even with the 87 octane. No CEL light, no knocking or pinging. Just yesterday it hit the half-empty mark, so I topped it off with 6 gallons of 93 octane.