Chevrolet: 98 Cavalier Overheating, blown head gasket, bars stop leak

Question
I just bought a used 98 cavalier and it was fine for a few days but yesterday I noticed my antifreeze was low. I could not fine dex-cool so I added Prestone Pre-mix for all makes, models and colors antifreeze. Now my car overheated once, but was fine after I let it sit. However, when I bought the car, the oil was amber colored and now it is darker brown with a pink tint and I noticed a little oil dripping from the front passenger side of the car. Is this problem from the antifreeze, or did I blow a head gasket. Would a cooling system sealer work, or maybe some Bars Stop? Please help. Thanks.

Answer
Amber ;
HI  you did nothing wrong by mixing the antifreeze. I   would look for a leak and if you do not find one you can add a can of bars stop leak to the rad. I swear by it for small holes. as far as the oil look to see where it is leaking from it might just be a gasket or a small drip. and if the oil is dirty I would change the oil and filter  ok. I do not think you have a blown head gasket.