Some engines are known to have moisture/condensation problems in the crankcase and cause "mayo" like gunk around the oil cap and throughout the PCV system.I have seen this problem a lot in four cylinder Volkswagen engines. In my experience so far, this chronic/latent problem is not known to occur in Bricks. Generally speaking, when oil mixes with water and gets cycled through an engine, it turns into the creamy crap you describe.
I'd say that coolant and oil are coming into contact with one another, and this can only really happen at two places: (1) head gasket, or (2) pump.
One thing is for sure -- while investigating this, take heed of Laitch's advice above and do not run/ride the bike with the temperature light on.