What should I do?

On May 31st 2016 a friend was doing an oil change on my vehicle I asked what was the loud noise that was coming from my vehicle he told me that I may have a manifold leak went online and researched it and I found that this is a problem with the year, make and model of my vehicle. I also researched and found that a lot of the owners of this vehicle were able to get Chevrolet to cover the cost of fixing the cracked exhaust manifold, but unlike myself the other owners of these vehicles had less miles on it then my vehicle, my vehicle has a hundred and twenty thousand miles on it. I am asking what should I do? Should I call Chevrolet to find out if they still have the extended warranty available?