Yesterday due to my stupidity, I overheated my car to the red zone and it was going and almosty stalled several times until I had a chance to park and leave it to cooll down. I cooled it down, filled it up with coolant and kept bleeding the system till it was air-free. Today the car overheated and kept behaving as if it had air in the system (temp going down when I rev the engine). I stopped cooled it down and SURPRISE I have "Tahini" Paste in the radiator. My mechanic suggested we tighten the cylinder head and it would stop the oil leak to the cooling system. What should I do exactly HELP ME OUT HERE BUDDIES