Octane to use?
 

I know someone with a 2012 Mini Cooper S and am kinda interested in one myself. It has about 120-130k (USA miles) on it and is running fine as far as I know. I can find similar mini's in a decent price range. But my main question is gasoline octane. This person supposedly only puts regular in it (86 or 87?) even though I think the fuel door says premium "recommended". This person also owned a BMW which required or recommended premium but used regular. The BMW lasted to about 140k as far as I know. Started burning oil around 130k or something and he couldn't figure out why. I think he got that BMW with less than 100k on it. I think the mini has probably only had 10k miles added to it, doesn't "ping" or anything as far as I know.

Can mini's run on regular gasoline? Will they hold up? How long do mini's last? Supposedly there was a coolant or oil leak that had to be fixed on the mini. My 10' Prius has 181.8k on it and just burns oil.

Thanks,
Higgins909