Many people like me don't drive our muscle cars when its real cold out. I like to have the windows down when I drive my 63 because I enjoy it more like that so I don't drive it in very cold weather. Its usually at least 55 to 60 degree's out when I drive mine. And I have used only an aftermarket cooler mounted in front of my rad. I have been driving and racing mine like this since 2006 and its still working great and the fluid is a nice red color. In fact I just raced it about a week and a half ago and it still shifts perfect and still runs 10.70's and 10.80's all day as it has since I put this eng in in 2011. My point being since I don't drive in real cold weather its worked fine since 2006 with just an aftermarket cooler. Ron