Q: What causes oil leak between head and block and whitish blue smoke from exhaust plus milky oil

This is a common sign of a blown cylinder head gasket. In between the cylinder head and block is a thick gasket that seals off the combustion chamber and maintains separation of the oil and water passages through the cylinder head and block. Although not always, typically when the engine overheats, this gasket will fail causing the motor to lose compression and eventually quit running. As a result of this, the engine will commonly emit a white smoke from the exhaust that is the result of burning oil and water along with the fuel inside the combustion chamber. You may also notice the oil to be a milky color as a result of the water mixing with the oil. In some cases, the oil may also contaminate the coolant system causing traces of oil to be found in the coolant. This is generally a very extensive repair job that will need to be handled by a qualified mechanic. I would recommend having an expert from YourMechanic come to your location to diagnose your situation to determine the best options for your repairs.