All cylinders filling with water

Another theory may very well be the waterpump/timing cover issue already brought up.
Water is thinner than oil which would make it easier to push past the rings/ring gaps. If the rototaing assembly is throwing the oil/water around and it's getting past the rings and into the cylinders then it's likely it may just sit up there like water does when you pull a head off when disassembling an engine. Not sure if this makes any sense, but the voice in my head tells me so. lol
Hmmmm.