I wouldn't go to 87, but I would go to 89 in cold weather. My dealer uses 89 to cure misfire problems here in cold weather. Your 89 may not be the same as ours here, gasoline varies widely across North America.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue