I think BMW advises lifetime ...but many poeple change it as some interval. Just make sure to use the "right" coolant. And be sure to stay away from any green coolant.
Sport Package, Rear Entertainment Package, Comfort Access, Cold Weather Package, Smoking Package, L7 High Def Audio
Mods = Powdercoated 149s, Black hood vent and kidneys, LED lighting update, BMW puddle lights (all doors), custom coding by "Triple_O_Coding" (including VIM), updated navi DVD from "PAPER", 90C hybrid thermostat.