The
oil needs to get hot to atleast boil out any contaminates,,,but it takes a good ride on the fwy to get up to 230. What happens when you put something cold on something hot? Stress!!! What temp does your motor run? Mine had a hard time reaching (water temp) 150 before I put the correct t-stat in. The
oil would not get hotter than the water. Now with a 195 t-stat the engine runs at 190 and the
oil will actually warm up. I have a '64 390fe.