Water in my engine oil. Where could it come from ?

[katy]

Also can be condensation build up from cold starts and short drives.

Ditto

I will try to close the water in and outlets and then try to blow air in . Maybe I will see or hear, where it leaks.

I would suggest that you don't do that as you could possibly damage your radiator.

Do you run straight water? Or anti-freeze mix? If you run anti-freeze mix then I would suspect condensation, as Tom suggested.