[KWMN33]

Just purchased a 2013 X5 35i Premium yesterday. My first ever Bimmer!

Quick question - and certainly there don't seem to be a shortage of threads about this, but wanted to ask specifically as it pertains to the X5:

Our local gas stations don't seem to have 91 Octane (the BMW recommended fuel) as often as they have a combo of 89 and 92/93. Is the wisest course of action to:

A) Always fill with 92/93 octane if there is no 91?
B) Always bill with 89 octane (it's just fine for this particular engine)
C) alternate between 89 and 93 (in theory, it evens out to 91!)
D) seek out gas stations that actually have 91 and just stick to using them

Any advice would be great!