I have white smoke coming from the exhaust of my car (espeically on start up), and some of my car enthusiast friends have told me that I have blown my head gasket.

My car is a Subaru Impreza, and because of the flat-four engine layout, I’m told that gasket replacement can be expensive due to the need to take the engine out and change the gasket on the other cylinder head at the same time.

Without wanting to go down this possibly expensive road, are there any tests I can do that will confirm that I have blown a gasket?