What were the first symtoms of your blown H.Gasket and how much was on the clock?
The car had done 120,000. The first I knew there was a problem was when the heater in the car stopped working ! I reported this at the service and they topped up the coolant and the heater stared working again but after only a few hundred miles it stopped again.
When they investigated in more detail they found oil in the coolant and diagnosed the gasket to be the cause.
,,,detail they found oil in the coolant
Maybe CO2,not oil?