Damage caused by water in the oil
When water gets in the oil from the refrigeration system or other sources, it emulsifies in the oil, increasing viscosity and causing corrosion and cavitation throughout the engine. Sometimes the heat boils off the water, but the minerals from the water continue, often showing as sodium and potassium, as in this sample (this engine did not have Antifreeze.
The high iron and lead corrosion in this sample were caused by the water from the cooling system.
In this sample we can see the residual minerals from 2 changes (a total of 838 hours). The third sample (november 9) actually had water that had not evaporated. Finally they believed it and fixed the source of water entrance. In the final sample on March 13, the results are back to normal except for some dirt and residual rust.
To show an idea of what water in the engine looks like mixed with the oil, I took off an oil pan when there were signs of water in the oil and took this picture of the lower part of the engine. You can see where the pump tried to suck foamy oil through the strainer to lubricate the engine.
