Leaking manifold gasket is more expensive to replace than car is worth (it had been vandalized). I tried the Blue Devil sealant and it has not worked. After googling the problem, I found this is a very common problem for these GM cars because the recommended coolant disintegrates the material the original manifold gasket was made of. I wish that there was a good, cheap fix - at least enough to get the car to last long enough to save up for another.