i read your threat and i also have the same problem mechanics told me the gaskit issue but my car have no issues of overheating ,No smoke from silencer , No water engine oil mixup so its mean that the gaskit is ok .
As i post above , i follow the instructions of XULFIQAR , but unfortunately i don't find the bleeding bolt on the radiator so i open a bolt which is placed on the metal pipe on which the top rubber pipe of the radiator is connected (on engine side) . so i remove the bolt
start the car
remove the radiator cap
when i removed the raditor cap the water comes out from the bleeding bolt
and it throws all the water from the bleeding bolt
i pour some more water which also comes out from the bleeding bolt
now off the engine put the bleeding bolt back
pour some water in the radiator
start the car with heater on
pour some more water to make the radiator full
and it leave it for five minutes ( but theses steps only solve 70 percent of my problem , i still have little bubbles in the radiator and also radiator makes pressure , when i open the radiator cap it sounds like opening of 7up bottle )
now i plan to service the radiator
( please get in touch with me so that we can find out the solution of our problem )