If is a head gasket leak is not that easy to get notice of it 'till you see the reservoir empty after being filled.
Now if the leak is from a line or so then your odds are much less $$$$$.
My VX develope a slow head gasket leak due to my own careless behavior when i didn't properly tight the radiator cap and the engine block overheated.
I am gonna rebuilt the entire engine depending on the cost other wise i'll gonna use it as a down payment for a trailblazer SS