[grayfish]

Thermostat?? . I am not sure about that motor , Kenny , I will run it across BIL .. Blowing oil ,,,, HOW??

Best of my recollection, the 60's have a themostat. I can't remeber but don't think they have a pressure (popit) valve. Check your model number and visit http://www.yamaha-motor.com/outboard/parts/home.aspx and look at the cylinder crankcase assembly for your model.