Slosh in my engine

What would be this light brownish creamy crap building up in my engine. What I notice when I take off my oil filler cap and my pvc lines is this brownish crap. Can anyone help me. It makes me a little nurveous. I just changed my oil about 900 miles ago. 3.8 1998 ford windstar with 121000 miles. VM

It really depends on the amount of brown crud there is. If there has been an extreme temperature change outside, there can be minor amounts built up due to condensation. If there is a lot and it is thick, you have coolant in the oil.

I guess ill take the optimistic answer first...lol The extreme tempature change makes since. I live in northestern ohio we just went from having 70 degree weather on thurs. then snow this week end. Then from snow on sunday to 58 degrees yesterday. Its been real damp too. I only see the crud just inside the oil fill cap filler on the inside valve cover. I did also see it in the pvc lines. There is no brownish crud on the dip stick even after it sat for 12 hours. I hope this is all it is. I do have a small anti freeze leak but I belive its external and real small. I see a small puddle on some white cardboard after sitting over night. Maybe a teaspoon. Thanks, VM