Just winterized my 2012 Centurion Carbon Pro with 5.7L PCM 343. Question is how do I know if the antifreeze reached the heater core? I'm always concerned because the last boat I had, Malibu Response LXi with Indmar engine, 2 out of 7 years the heater core froze and busted even after putting pink antifreeze through the system the same way. Is there another way to make sure there's no water left that will freeze?