The coolant bottle provides a quick visual method for determining that the coolant level is adequate. With the engine OFF and cold, the level of the engine coolant (antifreeze) in the bottle should be between the ranges indicated on the bottle.
The radiator normally remains completely full, so there is no need to remove the radiator/ coolant pressure cap unless checking for engine coolant freeze point or replacing coolant. 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, only OAT coolant that meets the requirements of the manufacturer Material Standard MS.90032 should be added to the coolant bottle. Do not overfill.