My 65 Commando 4sp. Barracuda came from Miami, FL just like me. We didn't worry that much about antifreeze, in fact I never did. I bought the car from a Plymouth dealer when it was less than six months old and less than a 1000 miles on it. PO bought it for his college bound son, who didn't like the four speed and the noise of the resonator, (HUH?) probably traded it for a 6 cylinder automatic station wagon, anyway I didn't ask. It travel with me up to Dover Delaware (USAF) in late November where it got down in the low teens a lot that winter and I had no cooling problems, until December of 1968. I was now stationed in Abilene, TX. While there, I was sent (short term) to Tachikawa, Japan where I was asked by a friend, "if I had charged the antifreeze in my car before we left for Japan?" No! I hadn't really done so since I bought it, just checked the water level now and then. My car was sitting in the parking lot, in front my barracks where the temperature went down below "0" several times. What antifreeze that was in it (if any) had failed. The engine block cracked from lifter hole to lifter hole and from freeze plug to freeze plug. Man I was really pissed, so pissed that I wrote a letter to Plymouth about it. "Your damn freeze plugs didn't work." Low and behold, I get a letter back from one of their engineers, who politely informed me that "contrary to most beliefs, those are not freeze plugs, but plugs used to close casting holes for the water jacket and were not intended to protect the block from freeze cracking." He went on to further state that the 273 had a very thin casting which contributed to the freeze cracking and the use of the 'true' freeze plug pre dated the newer (1965) engines by 20 some years. Oh yeah! He did say "sorry for your loss." The car sat in storage for two years, while I was overseas. What was the outcome? in 1970 a 273 block (new) cost me $200.00 and a $20.00 shipping charge by Greyhound. Most of all...I learned my lesson about the importance of antifreeze.
