I purchase a 743 that had some milky oil I paid accordingly. I put a balloon over the radiator filler and it does not seem to be pressurised. Now I assume that the head gasket would need to be bad, but then I read that there is a freeze plug in the from of the engine under the front cover. The article said this is the most likely problem not a head gasket is that true. That would be a lot easier to fix than a head gasket. I am not getting antifreeze in the cylinders and no white smoke. Any one done a lot of of them is there a way to verify what it is and how its getting into the oil?