AFAIK every major manufacturer since the mid-2000s has gone to a cooling system that completely keeps the air out. That is a critical for the newer organic acid coolants to be effective. It takes time for OAT & hybrid OAT coolants to build up its protective character in an engine and radiator. Once it does it can last a relatively long time compared to conventional IAT antifreeze. But since our systems are semi-open, the fast acting characteristics of conventional is the best match.
