It is called for in Inspection I, which is usually at 30,000 miles.

Every year seems a little early. If I was in a NYC, I might go every two years. As chefwong says, anything earlier than scheduled is personal preference.

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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