when you top off an S5 radiator, does it stay filled to the fill cap? or is it supposed to empty into the overflow a certain amount? i keep topping mine off, and it seems to fill the overflow about as much as i top off, but i never get a low coolant buzzer. is it normal or something i should be concerned about? thanks.

 

You should fill both. The radiator to the top and the overflow to the reccomended amount. If it backing into you overflow bottle thats a problem.

 

hmm... so the coolant level on the filler neck should stay full when the car is cool?

 

for a while it should, yes. Eventually you should have to top it off.