Believe it or not, in my situation it had alot to do with a new motor install and a tune. I never really had ONE issue that fixed this problem. Sorry for not being much help.

 

if it is a coolant seal--then just run the engine with the radiator cap off ( dont drive the car) if it is a coolant seal there will be bubbles in the overflow tank--no bubbles then the seals are ok and it is something else.

 

Quite smart. I have never heard of that. Good bit of information to know.

 

there is also a chemical test for this. idk what its called but my bro has it. blue liquid turns yellow if combustion gasses are present in coolant.