Coolant decreased

[drmagieed]

In my aveo 2009 I used acedelco green water 33% and I noticed that the coolant decreased rapidly in the surge tank I can add a liter of coolant each month. I checked everything and there is no leaking. I replaced the surge tank from about 4 years but I did not replace the surge tank cover for about 7 years. Is the problem come from the cap or not? and what is the possible cause of that issue. I forget there is no overheating and everything is OK.

[Melveo]

Seems fine, If it takes a month it should be fine. I top mines off every two weeks and it's always about half full at the time

[drmagieed]

Is there a problem in the cap?

[drmagieed]

Thanks
the problem was in the surge tank cap and I replaced it. this solved the problem.