I'm trying to help a friend of mine. He thinks his car may be in the early stages of a headgasket failure. I looked at his antifreeze and I'm on the fence if it's starting to get that look like exhaust is entering his cooling system. I know I could do some real work and figure out what's up, but I'm not that good of a friend of his, so a lab that would test would be much better. I called blackstone and got a no, Analysts Inc tests antifreeze but does not test for exhaust. I read about a mythical kit that Auto Zone carries to test with fluid that turns from blue to yellow but none of the stores around here know what it is.