When i went to get an oil change two weeks ago they filled up my coolant system, then when i check it today it was empty. So went and bought anti-freeze/coolant and filled it up again. when i got home i check and a quarter of the fluid was gone already. i checked if it was leaking but i didn't see any leaking. could it be that i was driving the car for almost a year without coolant and now when i fill it up it keeps drinking fast? help