I'm trying to buy a car but it has a blown head gasket and it is a 1996 cadilac seville

You need to post this under the proper category. Cars & Trucks.

Unless you have a lot of money to have this head gasket repaired don't buy the car. If you are a mechanic that knows how to fix and repair cars that's another story.

That might not be all that is wrong with this vehicle. Proceed at your own peril as the 1996 Cadillacs are notorious for having a lot of problems.

Try finding another car instead.