What is the water mixes with the oil? does it have an oil cooler. on 2007 Ford F-250 Super Duty

Diesel pick up was running fine. Al of a sudden it stop running. I noticed the oil has water in it. What could be the cause.

Asked by for the 2007 Ford F-250 Super Duty
Are you sure this is oil that is in mixed with the water? It might be fuel; in which case it could be a cracked, head or block or a cracked injector cup, or both.