I owned a 61 Vette with a 283 cu in motor that was known to have a problem with overheating. GM over the years of production of the C1 vette made various changes to cooling systems , fan sizes and more blades etc. but the problem never went away. One of the guys I worked with who was a real gear head was also a distributor for Amsoil. He suggested I try it. It made a huge difference in how my engine performed. On really hot humid days my car would get so hot if I stopped for any reason it would stall. Anyone who remembers driving old classic cars knows how the temp gauge would change with driving conditions. Going up steep hills the gauge goes up to max , coasting down hills the temp gauge goes down. Long explanation but real world results from using Amsoil in my engine made me a believer. The motor ran much cooler and smoother. I also put Amsoil transmission fluid in my baby and never had to double clutch again.
My 2 cents