Drugstore,com is a legit site. I'm studying to become a nationaly certified pharmacy tech from West Virginia University. They gave me this site as one of the legit ones along with Planetrx.COM
http://www.drugstore.com/pharmacy/drugindex/rxsearch.asp?search
Well you see changing the oil should fix the problem. Whether this doesn't work swap the Radiator. Whether that doesn't work go and dive into a pile of jelly.