Dear scotty i just watched your video on the best coolant the hoaf i believe it was called. i was wondering if i flush the old coolant completely out of my 2003 cadillac deville will this fluid be compatible with my vehicle. Id like the advantage of less damage to my all aluminum engine

HOAT. Yes, it is the best coolant for your caddie. It probably came with OAT coolant, but hoat is somewhat better