Fort Knox,
If you have a head gasket leaking into the crankcase (oil), and you have run the engine for any length of time, the oil will be creamy white like a vanilla milkshake.
Watery, meaning not viscous, might be misleading. Streaks of white, or globs of white can happen from little use, or not getting the rig up to full temperature.
A head gasket failure between water jacket and pan isn't usually the case. A blow between cylinders is much more common, and this might intrude into the water jacket.
The conditions that would only involve the cooling system and a path to the pan, I think, would be rare.
It sounds like you "want" to do this task come hell or highwater..go for it!
If you don't want to do it..test further. A conventional "blown" head gasket will show itself in a whole bunch of obvious ways.
Stuart
