Whilst fitting the head back on I drained the oil and left it draining over night, the next day I poured a few pints of oil in with the drain plug still removed just to flush out any water or carbon in the oil gallery’s.I changed the oil and this time the filter after about 50 miles, no signs of white residue in the oil filler cap, which you would normally associate with water in the oil, so I guess I must have flushed out any water before I started it up.