I often had to add more coolant into my car because the light was going on at a daily basis. I bought some of this stop-leak addidtive for radiators and the leakage stopped. I haven't had to put anymore coolant in after 1500 miles of driving. The stuff actually works, and it is only like 3 or 4 bucks. However, if you say its boiling in your resevoir, then it does sound like overheating to me. Might want to get that checked out.
