The level of the coolant in the pressurized coolant bottle should be between the “MIN” and “MAX” range on the bottle when the engine is cold.
The radiator normally remains completely full, so there is no need to remove the cap unless checking for coolant freeze point or replacing engine coolant (antifreeze). Advise your service attendant of this. As long as the engine operating temperature is satisfactory, the coolant bottle need only be checked once a month. When additional engine coolant is needed to maintain the proper level, it should be added to the coolant bottle. Do not overfill.