I have noticed that when my car is cool, ususally the morning, the coolant box (what exactly do u call this) the coolant is at it's MIN line
then after i drove it for a bit, it's on the MAX

is this normal?? or something wrong with my cooling system??
please let meknow

thanks

 

thats normal. the overflow is there to catch extra fluid. the fluid expands when it gets hot and the pressure inside the system is greater than the radiator cap is rated for then the extra fluid is pushed into that bottle. when the car cools off there is a vaccum and the fluid is pulled back into the cooling system

 

that's what i thought so

thanks for the explanation