Only when refilling!
WARNING: This page is about a different car, the 2010 BMW M6, 2009 BMW M6, 2008 BMW M6, 2007 BMW M6, and 2006 BMW M6. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT:
Do not fill coolant expansion tank over MAX level as overfilling will cause the coolant to overflow. This may give rise to traces of residual coolant on the expansion tank or in the engine compartment and wrongly suggest possible leakages.
Use only recommended coolant. See COOLING SYSTEM - OPERATING FLUIDS .
Perform filling operation slowly.
Adjust coolant level to MAX.
Close coolant expansion tank.
Installation:
Close cap (1) until the arrow marks line up.
IMPORTANT:
The following venting procedure is necessary e.g. when a part is replaced in the cooling system or when the cooling system is refilled.