hello i am after a bit of help i have a vs v6 commodore with a few problems it is loosing coolant but its not leaking out no drops vissable it overheats and it has like a milky junk around the valve springs and under the oil cap i was told by the mechanic it has blown a head gasket at chamber 7 before i go into paying big $$$$ could it be a head gasket or a inletmanifold gasket