Beagle,

I'm not talltimber but here's what I reasearched on it,,,,,,

Water vapor enters the crankcase of all motors from the atmosphere, and as a by-product of combustion. In other motors, the oil gets rather hot and any water vapor that may condense will steam-off and exit the crankcase breather. 4-stroke outboard motor oil doesn't get nearly as hot, so the water just keeps on collecting.

Check oil level and if it gets overfull this is the reason.