John D I must be using 180 in my 51 6400 because it stays on about 185 degrees summer and winter. This is with the original big radiator,heater works OK ,cab isn't real tight. If you have enough radiator to run 195 that would be even better if you don't overheat like in a traffic stall. Pressure cap is in that picture,along with how good your heater core is.
