Overheating

[robotype]

Thank you for the quick reply Ivan, I am sure the water is coming out from the reservoir because I have seen it spitting out a couple of times.
Yesterday I kept the engine on at the minimum for like one hour and the liquid in the reservoir raised 3 or 4 cm, is this normal? Then when it will be full it will come out from the pipe and that is why I found the radiator empty on the highway the other day...I can't find any other leak...

By the way, if the problem is the head gasket, should I get a 0.8 TRD metal one to replace it? Wouldn't it be too low also because they will flatten the head 0.3 mm or so...isn't the original 1.2 better in this case?

My mechanic in Milano is asking me 1000 euro to change the gasket,
he said this work includes many other things to fix and check like cleaning the valve and a bunch of other stuff I didn't get...but I don't know why...I have the impression he is not very honest...