WARNING: This page is about a different car, the 2012 Audi S5, 2011 Audi S5, and 2010 Audi S5. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Identifying Coolant Reservoir Marking
Courtesy of AUDI OF AMERICA, LLC
With the engine cold, coolant level must be at MAX marking.
Coolant level may be above MAX marking with engine at operating temperature.