I have a 2008 Pontiac GT G6- -had oil changed and was told leakage problem they found was no problem and they would check on next oil change. I went on road trip and the engine fan kept running when I came to a stop, so I had it checked, the mechanic said the problem was a blown head gasket, but they also said that the oil leakage had nothing to do with the blown head gasket, so what caused it then? No coolant was found in the oil.
There are several things that can cause a head gasket to blow, one is age, another is overheating, corrosive coolant could cause a blown head gasket. I would get a second opinion, it may cost you a few extra dollars, but mechanics misdiagnose head gaskets all the time, so it's worth spending the money. Let me know if you have more questions, thanks Karen.